* [RFC PATCH v5 23/45] x86/virt/tdx: Enable Dynamic PAMT
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
The Physical Address Metadata Table (PAMT) holds TDX metadata for
physical memory and must be allocated by the kernel during TDX module
initialization.
The exact size of the required PAMT memory is determined by the TDX
module and may vary between TDX module versions, but currently it is
approximately 0.4% of the system memory. This is a significant
commitment, especially if it is not known upfront whether the machine
will run any TDX guests.
The Dynamic PAMT feature reduces static PAMT allocations. PAMT_1G and
PAMT_2M levels are still allocated on TDX module initialization, but the
PAMT_4K level is allocated dynamically, reducing static allocations to
approximately 0.004% of the system memory.
All pieces are in place. Enable Dynamic PAMT if it is supported.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Tested-by: Sagi Shahar <sagis@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/tdx.h | 6 +++++-
arch/x86/virt/vmx/tdx/tdx.c | 8 ++++++++
arch/x86/virt/vmx/tdx/tdx.h | 3 ---
3 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index c39e2920d0c3..56bdfbce4289 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -12,6 +12,10 @@
#include <asm/trapnr.h>
#include <asm/shared/tdx.h>
+/* Bit definitions of TDX_FEATURES0 metadata field */
+#define TDX_FEATURES0_NO_RBP_MOD BIT_ULL(18)
+#define TDX_FEATURES0_DYNAMIC_PAMT BIT_ULL(36)
+
#ifndef __ASSEMBLER__
#include <uapi/asm/mce.h>
@@ -133,7 +137,7 @@ const struct tdx_sys_info *tdx_get_sysinfo(void);
static inline bool tdx_supports_dynamic_pamt(const struct tdx_sys_info *sysinfo)
{
- return false; /* To be enabled when kernel is ready */
+ return sysinfo->features.tdx_features0 & TDX_FEATURES0_DYNAMIC_PAMT;
}
/* Simple structure for pre-allocating Dynamic PAMT pages outside of locks. */
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 53b29c827520..90407493bb45 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -1068,6 +1068,8 @@ static int construct_tdmrs(struct list_head *tmb_list,
return ret;
}
+#define TDX_SYS_CONFIG_DYNAMIC_PAMT BIT(16)
+
static int config_tdx_module(struct tdmr_info_list *tdmr_list, u64 global_keyid)
{
struct tdx_module_args args = {};
@@ -1095,6 +1097,12 @@ static int config_tdx_module(struct tdmr_info_list *tdmr_list, u64 global_keyid)
args.rcx = __pa(tdmr_pa_array);
args.rdx = tdmr_list->nr_consumed_tdmrs;
args.r8 = global_keyid;
+
+ if (tdx_supports_dynamic_pamt(&tdx_sysinfo)) {
+ pr_info("Enable Dynamic PAMT\n");
+ args.r8 |= TDX_SYS_CONFIG_DYNAMIC_PAMT;
+ }
+
ret = seamcall_prerr(TDH_SYS_CONFIG, &args);
/* Free the array as it is not required anymore. */
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index 46c4214b79fb..096c78a1d438 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -86,9 +86,6 @@ struct tdmr_info {
DECLARE_FLEX_ARRAY(struct tdmr_reserved_area, reserved_areas);
} __packed __aligned(TDMR_INFO_ALIGNMENT);
-/* Bit definitions of TDX_FEATURES0 metadata field */
-#define TDX_FEATURES0_NO_RBP_MOD BIT(18)
-
/*
* Do not put any hardware-defined TDX structure representations below
* this comment!
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 22/45] KVM: TDX: Get/put PAMT pages when (un)mapping private memory
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Add Dynamic PAMT support to KVM's S-EPT MMU by "getting" a PAMT page when
adding guest memory (PAGE.ADD or PAGE.AUG), and "putting" the page when
removing guest memory (PAGE.REMOVE).
To access the per-vCPU PAMT caches without plumbing @vcpu throughout the
TDP MMU, begrudginly use kvm_get_running_vcpu() to get the vCPU, and bug
the VM If KVM attempts to set an S-EPT without an active vCPU. KVM only
supports creating _new_ mappings in page (pre)fault paths, all of which
require an active vCPU.
The PAMT memory holds metadata for TDX-protected memory. With Dynamic
PAMT, PAMT_4K is allocated on demand. The kernel supplies the TDX module
with a few pages that cover 2M of host physical memory.
PAMT memory can be reclaimed when the last user is gone. It can happen
in a few code paths:
- On TDH.PHYMEM.PAGE.RECLAIM in tdx_reclaim_td_control_pages() and
tdx_reclaim_page().
- On TDH.MEM.PAGE.REMOVE in tdx_sept_drop_private_spte().
- In tdx_sept_zap_private_spte() for pages that were in the queue to be
added with TDH.MEM.PAGE.ADD, but it never happened due to an error.
- In tdx_sept_free_private_spt() for SEPT pages;
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[Minor log tweak]
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/kvm-x86-ops.h | 1 +
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/mmu/mmu.c | 4 +++
arch/x86/kvm/vmx/tdx.c | 44 ++++++++++++++++++++++++++----
arch/x86/kvm/vmx/tdx.h | 2 ++
5 files changed, 47 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 17dddada69fc..394dc29483a7 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -99,6 +99,7 @@ KVM_X86_OP_OPTIONAL(free_external_sp)
KVM_X86_OP_OPTIONAL_RET0(set_external_spte)
KVM_X86_OP_OPTIONAL(remove_external_spte)
KVM_X86_OP_OPTIONAL(reclaim_external_sp)
+KVM_X86_OP_OPTIONAL_RET0(topup_external_cache)
KVM_X86_OP(has_wbinvd_exit)
KVM_X86_OP(get_l2_tsc_offset)
KVM_X86_OP(get_l2_tsc_multiplier)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 6e84dbc89e79..a6e4ab76b1b2 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1863,6 +1863,7 @@ struct kvm_x86_ops {
struct kvm_mmu_page *sp);
void (*remove_external_spte)(struct kvm *kvm, gfn_t gfn, enum pg_level level,
u64 mirror_spte);
+ int (*topup_external_cache)(struct kvm_vcpu *vcpu, int min);
bool (*has_wbinvd_exit)(void);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 9b5a6861e2a4..4ecbf216d96f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -605,6 +605,10 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect)
PT64_ROOT_MAX_LEVEL);
if (r)
return r;
+
+ r = kvm_x86_call(topup_external_cache)(vcpu, PT64_ROOT_MAX_LEVEL);
+ if (r)
+ return r;
}
r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadow_page_cache,
PT64_ROOT_MAX_LEVEL);
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 0946eba2de23..d74a2547e512 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -683,6 +683,8 @@ int tdx_vcpu_create(struct kvm_vcpu *vcpu)
if (!irqchip_split(vcpu->kvm))
return -EINVAL;
+ tdx_init_pamt_cache(&tdx->pamt_cache);
+
fpstate_set_confidential(&vcpu->arch.guest_fpu);
vcpu->arch.apic->guest_apic_protected = true;
INIT_LIST_HEAD(&tdx->vt.pi_wakeup_list);
@@ -868,6 +870,8 @@ void tdx_vcpu_free(struct kvm_vcpu *vcpu)
struct vcpu_tdx *tdx = to_tdx(vcpu);
int i;
+ tdx_free_pamt_cache(&tdx->pamt_cache);
+
if (vcpu->cpu != -1) {
KVM_BUG_ON(tdx->state == VCPU_TD_STATE_INITIALIZED, vcpu->kvm);
tdx_flush_vp_on_cpu(vcpu);
@@ -1615,6 +1619,14 @@ void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int pgd_level)
td_vmcs_write64(to_tdx(vcpu), SHARED_EPT_POINTER, root_hpa);
}
+static int tdx_topup_external_pamt_cache(struct kvm_vcpu *vcpu, int min)
+{
+ if (!tdx_supports_dynamic_pamt(tdx_sysinfo))
+ return 0;
+
+ return tdx_topup_pamt_cache(&to_tdx(vcpu)->pamt_cache, min);
+}
+
static int tdx_mem_page_add(struct kvm *kvm, gfn_t gfn, enum pg_level level,
kvm_pfn_t pfn)
{
@@ -1696,8 +1708,15 @@ static int tdx_sept_link_private_spt(struct kvm *kvm, gfn_t gfn,
static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
enum pg_level level, u64 mirror_spte)
{
+ struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
kvm_pfn_t pfn = spte_to_pfn(mirror_spte);
+ struct vcpu_tdx *tdx = to_tdx(vcpu);
+ struct page *page = pfn_to_page(pfn);
+ int ret;
+
+ if (KVM_BUG_ON(!vcpu, kvm))
+ return -EINVAL;
if (KVM_BUG_ON(!is_shadow_present_pte(mirror_spte), kvm))
return -EIO;
@@ -1711,6 +1730,10 @@ static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
WARN_ON_ONCE((mirror_spte & VMX_EPT_RWX_MASK) != VMX_EPT_RWX_MASK);
+ ret = tdx_pamt_get(page, &tdx->pamt_cache);
+ if (ret)
+ return ret;
+
/*
* Ensure pre_fault_allowed is read by kvm_arch_vcpu_pre_fault_memory()
* before kvm_tdx->state. Userspace must not be allowed to pre-fault
@@ -1723,14 +1746,17 @@ static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
* If the TD isn't finalized/runnable, then userspace is initializing
* the VM image via KVM_TDX_INIT_MEM_REGION; ADD the page to the TD.
*/
- if (unlikely(kvm_tdx->state != TD_STATE_RUNNABLE))
- return tdx_mem_page_add(kvm, gfn, level, pfn);
+ if (likely(kvm_tdx->state == TD_STATE_RUNNABLE))
+ ret = tdx_mem_page_aug(kvm, gfn, level, pfn);
+ else
+ ret = tdx_mem_page_add(kvm, gfn, level, pfn);
- return tdx_mem_page_aug(kvm, gfn, level, pfn);
+ if (ret)
+ tdx_pamt_put(page);
+
+ return ret;
}
-
-
/*
* Ensure shared and private EPTs to be flushed on all vCPUs.
* tdh_mem_track() is the only caller that increases TD epoch. An increase in
@@ -1847,6 +1873,7 @@ static void tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn,
return;
tdx_quirk_reset_page(page);
+ tdx_pamt_put(page);
}
void tdx_deliver_interrupt(struct kvm_lapic *apic, int delivery_mode,
@@ -3614,5 +3641,12 @@ void __init tdx_hardware_setup(void)
vt_x86_ops.set_external_spte = tdx_sept_set_private_spte;
vt_x86_ops.reclaim_external_sp = tdx_sept_reclaim_private_sp;
vt_x86_ops.remove_external_spte = tdx_sept_remove_private_spte;
+
+ /*
+ * FIXME: Wire up the PAMT hook iff DPAMT is supported, once VMXON is
+ * moved out of KVM and tdx_bringup() is folded into here.
+ */
+ vt_x86_ops.topup_external_cache = tdx_topup_external_pamt_cache;
+
vt_x86_ops.protected_apic_has_interrupt = tdx_protected_apic_has_interrupt;
}
diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h
index ce2720a028ad..f444fc84d93b 100644
--- a/arch/x86/kvm/vmx/tdx.h
+++ b/arch/x86/kvm/vmx/tdx.h
@@ -73,6 +73,8 @@ struct vcpu_tdx {
u64 map_gpa_next;
u64 map_gpa_end;
+
+ struct tdx_pamt_cache pamt_cache;
};
void tdh_vp_rd_failed(struct vcpu_tdx *tdx, char *uclass, u32 field, u64 err);
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 21/45] x86/tdx: Add APIs to support get/put of DPAMT entries from KVM, under spinlock
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
From: Rick Edgecombe <rick.p.edgecombe@intel.com>
Implement a PAMT "caching" scheme, similar to KVM's pre-allocated cache of
MMU assets, along with APIs to allow KVM to pre-allocate PAMT pages before
acquiring its mmu_lock spinlock, but wait until S-EPT entries are created
to actually update the Dynamic PAMT.
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/tdx.h | 17 ++++++++++
arch/x86/virt/vmx/tdx/tdx.c | 65 +++++++++++++++++++++++++++++++++----
2 files changed, 76 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index fa29be18498c..c39e2920d0c3 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -136,6 +136,23 @@ static inline bool tdx_supports_dynamic_pamt(const struct tdx_sys_info *sysinfo)
return false; /* To be enabled when kernel is ready */
}
+/* Simple structure for pre-allocating Dynamic PAMT pages outside of locks. */
+struct tdx_pamt_cache {
+ struct list_head page_list;
+ int cnt;
+};
+
+static inline void tdx_init_pamt_cache(struct tdx_pamt_cache *cache)
+{
+ INIT_LIST_HEAD(&cache->page_list);
+ cache->cnt = 0;
+}
+
+void tdx_free_pamt_cache(struct tdx_pamt_cache *cache);
+int tdx_topup_pamt_cache(struct tdx_pamt_cache *cache, unsigned long npages);
+int tdx_pamt_get(struct page *page, struct tdx_pamt_cache *cache);
+void tdx_pamt_put(struct page *page);
+
void tdx_quirk_reset_page(struct page *page);
int tdx_guest_keyid_alloc(void);
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index d333d2790913..53b29c827520 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -2064,13 +2064,34 @@ u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page)
}
EXPORT_SYMBOL_FOR_KVM(tdh_phymem_page_wbinvd_hkid);
-static int alloc_pamt_array(u64 *pa_array)
+static struct page *tdx_alloc_page_pamt_cache(struct tdx_pamt_cache *cache)
+{
+ struct page *page;
+
+ page = list_first_entry_or_null(&cache->page_list, struct page, lru);
+ if (page) {
+ list_del(&page->lru);
+ cache->cnt--;
+ }
+
+ return page;
+}
+
+static struct page *alloc_dpamt_page(struct tdx_pamt_cache *cache)
+{
+ if (cache)
+ return tdx_alloc_page_pamt_cache(cache);
+
+ return alloc_page(GFP_KERNEL_ACCOUNT);
+}
+
+static int alloc_pamt_array(u64 *pa_array, struct tdx_pamt_cache *cache)
{
struct page *page;
int i;
for (i = 0; i < tdx_dpamt_entry_pages(); i++) {
- page = alloc_page(GFP_KERNEL_ACCOUNT);
+ page = alloc_dpamt_page(cache);
if (!page)
goto err;
pa_array[i] = page_to_phys(page);
@@ -2151,7 +2172,7 @@ static u64 tdh_phymem_pamt_remove(struct page *page, u64 *pamt_pa_array)
static DEFINE_SPINLOCK(pamt_lock);
/* Bump PAMT refcount for the given page and allocate PAMT memory if needed */
-static int tdx_pamt_get(struct page *page)
+int tdx_pamt_get(struct page *page, struct tdx_pamt_cache *cache)
{
u64 pamt_pa_array[MAX_NR_DPAMT_ARGS];
atomic_t *pamt_refcount;
@@ -2170,7 +2191,7 @@ static int tdx_pamt_get(struct page *page)
if (atomic_inc_not_zero(pamt_refcount))
return 0;
- ret = alloc_pamt_array(pamt_pa_array);
+ ret = alloc_pamt_array(pamt_pa_array, cache);
if (ret)
goto out_free;
@@ -2222,12 +2243,13 @@ static int tdx_pamt_get(struct page *page)
free_pamt_array(pamt_pa_array);
return ret;
}
+EXPORT_SYMBOL_FOR_KVM(tdx_pamt_get);
/*
* Drop PAMT refcount for the given page and free PAMT memory if it is no
* longer needed.
*/
-static void tdx_pamt_put(struct page *page)
+void tdx_pamt_put(struct page *page)
{
u64 pamt_pa_array[MAX_NR_DPAMT_ARGS];
atomic_t *pamt_refcount;
@@ -2281,6 +2303,37 @@ static void tdx_pamt_put(struct page *page)
*/
free_pamt_array(pamt_pa_array);
}
+EXPORT_SYMBOL_FOR_KVM(tdx_pamt_put);
+
+void tdx_free_pamt_cache(struct tdx_pamt_cache *cache)
+{
+ struct page *page;
+
+ while ((page = tdx_alloc_page_pamt_cache(cache)))
+ __free_page(page);
+}
+EXPORT_SYMBOL_FOR_KVM(tdx_free_pamt_cache);
+
+int tdx_topup_pamt_cache(struct tdx_pamt_cache *cache, unsigned long npages)
+{
+ if (WARN_ON_ONCE(!tdx_supports_dynamic_pamt(&tdx_sysinfo)))
+ return 0;
+
+ npages *= tdx_dpamt_entry_pages();
+
+ while (cache->cnt < npages) {
+ struct page *page = alloc_page(GFP_KERNEL_ACCOUNT);
+
+ if (!page)
+ return -ENOMEM;
+
+ list_add(&page->lru, &cache->page_list);
+ cache->cnt++;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_FOR_KVM(tdx_topup_pamt_cache);
/*
* Return a page that can be gifted to the TDX-Module for use as a "control"
@@ -2296,7 +2349,7 @@ struct page *__tdx_alloc_control_page(gfp_t gfp)
if (!page)
return NULL;
- if (tdx_pamt_get(page)) {
+ if (tdx_pamt_get(page, NULL)) {
__free_page(page);
return NULL;
}
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 20/45] KVM: x86/mmu: Allocate/free S-EPT pages using tdx_{alloc,free}_control_page()
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
Now that kvm_mmu_memory_cache supports custom page allocators, wire up the
S-EPT cache to use tdx_{alloc,free}_control_page() (arguably S-EPT pages
aren't "control" pages, but they're not guest pages either). Using the
TDX APIs will make S-EPT pages naturally play nice with Dynamic PAMT, by
virtue of adding/removing PAMT entries when S-EPT pages are allocated and
freed, as opposed to when they are added/removed from the S-EPT tree.
Inserting into the PAMT entries on allocation does mean KVM will create
unnecessary PAMT entries, e.g. once a vCPU stops faulting in memory, the
remaining pages in the MMU cache will go unused. But in practice, odds
are very good the containing 2MiB page will have other in-use S-EPT pages,
i.e. will create PAMT entries anyways. And _if_ creating PAMT entries on
allocation is problematic for memory consumption, that can be resolved by
tweaking KVM's cache size.
Suggested-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/kvm-x86-ops.h | 2 ++
arch/x86/include/asm/kvm_host.h | 18 +++++++++---------
arch/x86/kvm/mmu/mmu.c | 6 ++++--
arch/x86/kvm/mmu/mmu_internal.h | 11 -----------
arch/x86/kvm/mmu/tdp_mmu.c | 5 +++--
arch/x86/kvm/vmx/tdx.c | 13 ++++++++++++-
6 files changed, 30 insertions(+), 25 deletions(-)
diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index c17cedc485c9..17dddada69fc 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -94,6 +94,8 @@ KVM_X86_OP_OPTIONAL_RET0(set_tss_addr)
KVM_X86_OP_OPTIONAL_RET0(set_identity_map_addr)
KVM_X86_OP_OPTIONAL_RET0(get_mt_mask)
KVM_X86_OP(load_mmu_pgd)
+KVM_X86_OP_OPTIONAL(alloc_external_sp)
+KVM_X86_OP_OPTIONAL(free_external_sp)
KVM_X86_OP_OPTIONAL_RET0(set_external_spte)
KVM_X86_OP_OPTIONAL(remove_external_spte)
KVM_X86_OP_OPTIONAL(reclaim_external_sp)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b35a07ed11fb..6e84dbc89e79 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -867,10 +867,7 @@ struct kvm_vcpu_arch {
struct kvm_mmu_memory_cache mmu_shadow_page_cache;
struct kvm_mmu_memory_cache mmu_shadowed_info_cache;
struct kvm_mmu_memory_cache mmu_page_header_cache;
- /*
- * This cache is to allocate external page table. E.g. private EPT used
- * by the TDX module.
- */
+ /* Used to allocate S-EPT pages (gifted to the TDX-Module). */
struct kvm_mmu_memory_cache mmu_external_spt_cache;
/*
@@ -1853,18 +1850,21 @@ struct kvm_x86_ops {
void (*load_mmu_pgd)(struct kvm_vcpu *vcpu, hpa_t root_hpa,
int root_level);
- /* Update the external page table from spte getting set. */
+ /*
+ * Callbacks to allocate and free external page tables, a.k.a. S-EPT,
+ * and to propagate changes in mirror page tables to the external page
+ * tables.
+ */
+ unsigned long (*alloc_external_sp)(gfp_t gfp);
+ void (*free_external_sp)(unsigned long addr);
int (*set_external_spte)(struct kvm *kvm, gfn_t gfn, enum pg_level level,
u64 mirror_spte);
-
- /* Update external page tables for page table about to be freed. */
void (*reclaim_external_sp)(struct kvm *kvm, gfn_t gfn,
struct kvm_mmu_page *sp);
-
- /* Update external page table from spte getting removed, and flush TLB. */
void (*remove_external_spte)(struct kvm *kvm, gfn_t gfn, enum pg_level level,
u64 mirror_spte);
+
bool (*has_wbinvd_exit)(void);
u64 (*get_l2_tsc_offset)(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 3911ac9bddfd..9b5a6861e2a4 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -6690,11 +6690,13 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;
- vcpu->arch.mmu_shadow_page_cache.init_value =
- SHADOW_NONPRESENT_VALUE;
+ vcpu->arch.mmu_shadow_page_cache.init_value = SHADOW_NONPRESENT_VALUE;
if (!vcpu->arch.mmu_shadow_page_cache.init_value)
vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
+ vcpu->arch.mmu_external_spt_cache.page_get = kvm_x86_ops.alloc_external_sp;
+ vcpu->arch.mmu_external_spt_cache.page_free = kvm_x86_ops.free_external_sp;
+
vcpu->arch.mmu = &vcpu->arch.root_mmu;
vcpu->arch.walk_mmu = &vcpu->arch.root_mmu;
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index 73cdcbccc89e..6bb97f660793 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -157,17 +157,6 @@ static inline bool is_mirror_sp(const struct kvm_mmu_page *sp)
return sp->role.is_mirror;
}
-static inline void kvm_mmu_alloc_external_spt(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
-{
- /*
- * external_spt is allocated for TDX module to hold private EPT mappings,
- * TDX module will initialize the page by itself.
- * Therefore, KVM does not need to initialize or access external_spt.
- * KVM only interacts with sp->spt for private EPT operations.
- */
- sp->external_spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_external_spt_cache);
-}
-
static inline gfn_t kvm_gfn_root_bits(const struct kvm *kvm, const struct kvm_mmu_page *root)
{
/*
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 18764dbc97ea..01e3e4f4baa5 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -55,7 +55,8 @@ void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm)
static void tdp_mmu_free_sp(struct kvm_mmu_page *sp)
{
- free_page((unsigned long)sp->external_spt);
+ if (sp->external_spt)
+ kvm_x86_call(free_external_sp)((unsigned long)sp->external_spt);
free_page((unsigned long)sp->spt);
kmem_cache_free(mmu_page_header_cache, sp);
}
@@ -1246,7 +1247,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
sp = tdp_mmu_alloc_sp(vcpu);
tdp_mmu_init_child_sp(sp, &iter);
if (is_mirror_sp(sp))
- kvm_mmu_alloc_external_spt(vcpu, sp);
+ sp->external_spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_external_spt_cache);
sp->nx_huge_page_disallowed = fault->huge_page_disallowed;
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 323aae4300a1..0946eba2de23 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1790,7 +1790,9 @@ static void tdx_sept_reclaim_private_sp(struct kvm *kvm, gfn_t gfn,
* TD's hkid is freed, when the TD is being torn down.
*
* If the S-EPT PTE can't be removed for any reason, intentionally leak
- * the page to prevent the kernel from accessing the encrypted page.
+ * the page to prevent the kernel from accessing the encrypted page,
+ * and if Dynamic PAMT is enabled, to avoid inducing a failure on
+ * removal of the still-used PAMT entry.
*/
if (KVM_BUG_ON(is_hkid_assigned(to_kvm_tdx(kvm)), kvm) ||
tdx_reclaim_page(virt_to_page(sp->external_spt)))
@@ -3600,6 +3602,15 @@ void __init tdx_hardware_setup(void)
*/
vt_x86_ops.vm_size = max_t(unsigned int, vt_x86_ops.vm_size, sizeof(struct kvm_tdx));
+ /*
+ * TDX uses the external_spt cache to allocate S-EPT page table pages,
+ * which (a) don't need to be initialized by KVM as the TDX-Module will
+ * initialize the page (using the guest's encryption key), and (b) need
+ * to use a custom allocator to be compatible with Dynamic PAMT.
+ */
+ vt_x86_ops.alloc_external_sp = tdx_alloc_control_page;
+ vt_x86_ops.free_external_sp = tdx_free_control_page;
+
vt_x86_ops.set_external_spte = tdx_sept_set_private_spte;
vt_x86_ops.reclaim_external_sp = tdx_sept_reclaim_private_sp;
vt_x86_ops.remove_external_spte = tdx_sept_remove_private_spte;
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 19/45] KVM: Allow owner of kvm_mmu_memory_cache to provide a custom page allocator
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
Extend "struct kvm_mmu_memory_cache" to support a custom page allocator
so that x86's TDX can update per-page metadata on allocation and free().
Name the allocator page_get() to align with __get_free_page(), e.g. to
communicate that it returns an "unsigned long", not a "struct page", and
to avoid collisions with macros, e.g. with alloc_page.
Suggested-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
include/linux/kvm_types.h | 2 ++
virt/kvm/kvm_main.c | 7 ++++++-
2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index a568d8e6f4e8..87fa9deffdb7 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -112,6 +112,8 @@ struct kvm_mmu_memory_cache {
gfp_t gfp_custom;
u64 init_value;
struct kmem_cache *kmem_cache;
+ unsigned long (*page_get)(gfp_t gfp);
+ void (*page_free)(unsigned long addr);
int capacity;
int nobjs;
void **objects;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 571cf0d6ec01..7015edce5bd8 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -356,7 +356,10 @@ static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
if (mc->kmem_cache)
return kmem_cache_alloc(mc->kmem_cache, gfp_flags);
- page = (void *)__get_free_page(gfp_flags);
+ if (mc->page_get)
+ page = (void *)mc->page_get(gfp_flags);
+ else
+ page = (void *)__get_free_page(gfp_flags);
if (page && mc->init_value)
memset64(page, mc->init_value, PAGE_SIZE / sizeof(u64));
return page;
@@ -416,6 +419,8 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
while (mc->nobjs) {
if (mc->kmem_cache)
kmem_cache_free(mc->kmem_cache, mc->objects[--mc->nobjs]);
+ else if (mc->page_free)
+ mc->page_free((unsigned long)mc->objects[--mc->nobjs]);
else
free_page((unsigned long)mc->objects[--mc->nobjs]);
}
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 18/45] KVM: TDX: Allocate PAMT memory for TD and vCPU control structures
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
TDX TD control structures are provided to the TDX module at 4KB page size
and require PAMT backing. This means for Dynamic PAMT they need to also
have 4KB backings installed. Use the recently introduce TDX APIs for
allocating/freeing control pages, which handle DPAMT maintenance, to
allocate/free TD and vCPU pages for TDX guests.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[update log]
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
[sean: handle alloc+free+reclaim in one patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/vmx/tdx.c | 35 ++++++++++++++---------------------
1 file changed, 14 insertions(+), 21 deletions(-)
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 4ef414ee27b4..323aae4300a1 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -360,7 +360,7 @@ static void tdx_reclaim_control_page(struct page *ctrl_page)
if (tdx_reclaim_page(ctrl_page))
return;
- __free_page(ctrl_page);
+ __tdx_free_control_page(ctrl_page);
}
struct tdx_flush_vp_arg {
@@ -597,7 +597,7 @@ static void tdx_reclaim_td_control_pages(struct kvm *kvm)
tdx_quirk_reset_page(kvm_tdx->td.tdr_page);
- __free_page(kvm_tdx->td.tdr_page);
+ __tdx_free_control_page(kvm_tdx->td.tdr_page);
kvm_tdx->td.tdr_page = NULL;
}
@@ -2412,7 +2412,7 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
atomic_inc(&nr_configured_hkid);
- tdr_page = alloc_page(GFP_KERNEL_ACCOUNT);
+ tdr_page = __tdx_alloc_control_page(GFP_KERNEL_ACCOUNT);
if (!tdr_page)
goto free_hkid;
@@ -2425,7 +2425,7 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
goto free_tdr;
for (i = 0; i < kvm_tdx->td.tdcs_nr_pages; i++) {
- tdcs_pages[i] = alloc_page(GFP_KERNEL_ACCOUNT);
+ tdcs_pages[i] = __tdx_alloc_control_page(GFP_KERNEL_ACCOUNT);
if (!tdcs_pages[i])
goto free_tdcs;
}
@@ -2543,10 +2543,8 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
teardown:
/* Only free pages not yet added, so start at 'i' */
for (; i < kvm_tdx->td.tdcs_nr_pages; i++) {
- if (tdcs_pages[i]) {
- __free_page(tdcs_pages[i]);
- tdcs_pages[i] = NULL;
- }
+ __tdx_free_control_page(tdcs_pages[i]);
+ tdcs_pages[i] = NULL;
}
if (!kvm_tdx->td.tdcs_pages)
kfree(tdcs_pages);
@@ -2561,16 +2559,13 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
free_cpumask_var(packages);
free_tdcs:
- for (i = 0; i < kvm_tdx->td.tdcs_nr_pages; i++) {
- if (tdcs_pages[i])
- __free_page(tdcs_pages[i]);
- }
+ for (i = 0; i < kvm_tdx->td.tdcs_nr_pages; i++)
+ __tdx_free_control_page(tdcs_pages[i]);
kfree(tdcs_pages);
kvm_tdx->td.tdcs_pages = NULL;
free_tdr:
- if (tdr_page)
- __free_page(tdr_page);
+ __tdx_free_control_page(tdr_page);
kvm_tdx->td.tdr_page = NULL;
free_hkid:
@@ -2900,7 +2895,7 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
int ret, i;
u64 err;
- page = alloc_page(GFP_KERNEL_ACCOUNT);
+ page = __tdx_alloc_control_page(GFP_KERNEL_ACCOUNT);
if (!page)
return -ENOMEM;
tdx->vp.tdvpr_page = page;
@@ -2920,7 +2915,7 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
}
for (i = 0; i < kvm_tdx->td.tdcx_nr_pages; i++) {
- page = alloc_page(GFP_KERNEL_ACCOUNT);
+ page = __tdx_alloc_control_page(GFP_KERNEL_ACCOUNT);
if (!page) {
ret = -ENOMEM;
goto free_tdcx;
@@ -2942,7 +2937,7 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
* method, but the rest are freed here.
*/
for (; i < kvm_tdx->td.tdcx_nr_pages; i++) {
- __free_page(tdx->vp.tdcx_pages[i]);
+ __tdx_free_control_page(tdx->vp.tdcx_pages[i]);
tdx->vp.tdcx_pages[i] = NULL;
}
return -EIO;
@@ -2970,16 +2965,14 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
free_tdcx:
for (i = 0; i < kvm_tdx->td.tdcx_nr_pages; i++) {
- if (tdx->vp.tdcx_pages[i])
- __free_page(tdx->vp.tdcx_pages[i]);
+ __tdx_free_control_page(tdx->vp.tdcx_pages[i]);
tdx->vp.tdcx_pages[i] = NULL;
}
kfree(tdx->vp.tdcx_pages);
tdx->vp.tdcx_pages = NULL;
free_tdvpr:
- if (tdx->vp.tdvpr_page)
- __free_page(tdx->vp.tdvpr_page);
+ __tdx_free_control_page(tdx->vp.tdvpr_page);
tdx->vp.tdvpr_page = NULL;
tdx->vp.tdvpr_pa = 0;
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 17/45] x86/virt/tdx: Optimize tdx_alloc/free_control_page() helpers
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Optimize the PAMT alloc/free helpers to avoid taking the global lock when
possible.
The recently introduced PAMT alloc/free helpers maintain a refcount to
keep track of when it is ok to reclaim and free a 4KB PAMT page. This
refcount is protected by a global lock in order to guarantee that races
don’t result in the PAMT getting freed while another caller requests it
be mapped. But a global lock is a bit heavyweight, especially since the
refcounts can be (already are) updated atomically.
A simple approach would be to increment/decrement the refcount outside of
the lock before actually adjusting the PAMT, and only adjust the PAMT if
the refcount transitions from/to 0. This would correctly allocate and free
the PAMT page without getting out of sync. But there it leaves a race
where a simultaneous caller could see the refcount already incremented and
return before it is actually mapped.
So treat the refcount 0->1 case as a special case. On add, if the refcount
is zero *don’t* increment the refcount outside the lock (to 1). Always
take the lock in that case and only set the refcount to 1 after the PAMT
is actually added. This way simultaneous adders, when PAMT is not
installed yet, will take the slow lock path.
On the 1->0 case, it is ok to return from tdx_pamt_put() when the DPAMT is
not actually freed yet, so the basic approach works. Just decrement the
refcount before taking the lock. Only do the lock and removal of the PAMT
when the refcount goes to zero.
There is an asymmetry between tdx_pamt_get() and tdx_pamt_put() in that
tdx_pamt_put() goes 1->0 outside the lock, but tdx_pamt_get() does 0-1
inside the lock. Because of this, there is a special race where
tdx_pamt_put() could decrement the refcount to zero before the PAMT is
actually removed, and tdx_pamt_get() could try to do a PAMT.ADD when the
page is already mapped. Luckily the TDX module will tell return a special
error that tells us we hit this case. So handle it specially by looking
for the error code.
The optimization is a little special, so make the code extra commented
and verbose.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[Clean up code, update log]
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Tested-by: Sagi Shahar <sagis@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/shared/tdx_errno.h | 2 +
arch/x86/virt/vmx/tdx/tdx.c | 69 +++++++++++++++++++------
2 files changed, 54 insertions(+), 17 deletions(-)
diff --git a/arch/x86/include/asm/shared/tdx_errno.h b/arch/x86/include/asm/shared/tdx_errno.h
index e302aed31b50..acf7197527da 100644
--- a/arch/x86/include/asm/shared/tdx_errno.h
+++ b/arch/x86/include/asm/shared/tdx_errno.h
@@ -21,6 +21,7 @@
#define TDX_PREVIOUS_TLB_EPOCH_BUSY 0x8000020100000000ULL
#define TDX_RND_NO_ENTROPY 0x8000020300000000ULL
#define TDX_PAGE_METADATA_INCORRECT 0xC000030000000000ULL
+#define TDX_HPA_RANGE_NOT_FREE 0xC000030400000000ULL
#define TDX_VCPU_NOT_ASSOCIATED 0x8000070200000000ULL
#define TDX_KEY_GENERATION_FAILED 0x8000080000000000ULL
#define TDX_KEY_STATE_INCORRECT 0xC000081100000000ULL
@@ -94,6 +95,7 @@ DEFINE_TDX_ERRNO_HELPER(TDX_SUCCESS);
DEFINE_TDX_ERRNO_HELPER(TDX_RND_NO_ENTROPY);
DEFINE_TDX_ERRNO_HELPER(TDX_OPERAND_INVALID);
DEFINE_TDX_ERRNO_HELPER(TDX_OPERAND_BUSY);
+DEFINE_TDX_ERRNO_HELPER(TDX_HPA_RANGE_NOT_FREE);
DEFINE_TDX_ERRNO_HELPER(TDX_VCPU_NOT_ASSOCIATED);
DEFINE_TDX_ERRNO_HELPER(TDX_FLUSHVP_NOT_DONE);
DEFINE_TDX_ERRNO_HELPER(TDX_SW_ERROR);
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 682c8a228b53..d333d2790913 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -2161,16 +2161,23 @@ static int tdx_pamt_get(struct page *page)
if (!tdx_supports_dynamic_pamt(&tdx_sysinfo))
return 0;
+ pamt_refcount = tdx_find_pamt_refcount(page_to_pfn(page));
+
+ /*
+ * If the pamt page is already added (i.e. refcount >= 1),
+ * then just increment the refcount.
+ */
+ if (atomic_inc_not_zero(pamt_refcount))
+ return 0;
+
ret = alloc_pamt_array(pamt_pa_array);
if (ret)
goto out_free;
- pamt_refcount = tdx_find_pamt_refcount(page_to_pfn(page));
-
scoped_guard(spinlock, &pamt_lock) {
/*
- * If the pamt page is already added (i.e. refcount >= 1),
- * then just increment the refcount.
+ * Lost race to other tdx_pamt_add(). Other task has already allocated
+ * PAMT memory for the HPA.
*/
if (atomic_read(pamt_refcount)) {
atomic_inc(pamt_refcount);
@@ -2179,12 +2186,30 @@ static int tdx_pamt_get(struct page *page)
/* Try to add the pamt page and take the refcount 0->1. */
tdx_status = tdh_phymem_pamt_add(page, pamt_pa_array);
- if (WARN_ON_ONCE(!IS_TDX_SUCCESS(tdx_status))) {
+ if (IS_TDX_SUCCESS(tdx_status)) {
+ /*
+ * The refcount is zero, and this locked path is the only way to
+ * increase it from 0-1. If the PAMT.ADD was successful, set it
+ * to 1 (obviously).
+ */
+ atomic_set(pamt_refcount, 1);
+ } else if (IS_TDX_HPA_RANGE_NOT_FREE(tdx_status)) {
+ /*
+ * Less obviously, another CPU's call to tdx_pamt_put() could have
+ * decremented the refcount before entering its lock section.
+ * In this case, the PAMT is not actually removed yet. Luckily
+ * TDX module tells about this case, so increment the refcount
+ * 0-1, so tdx_pamt_put() skips its pending PAMT.REMOVE.
+ *
+ * The call didn't need the pages though, so free them.
+ */
+ atomic_set(pamt_refcount, 1);
+ goto out_free;
+ } else {
+ WARN_ON_ONCE(1);
ret = -EIO;
goto out_free;
}
-
- atomic_inc(pamt_refcount);
}
return 0;
@@ -2213,15 +2238,21 @@ static void tdx_pamt_put(struct page *page)
pamt_refcount = tdx_find_pamt_refcount(page_to_pfn(page));
+ /*
+ * If the there are more than 1 references on the pamt page,
+ * don't remove it yet. Just decrement the refcount.
+ *
+ * Unlike the paired call in tdx_pamt_get(), decrement the refcount
+ * outside the lock even if it's the special 0<->1 transition. See
+ * special logic around HPA_RANGE_NOT_FREE in tdx_pamt_get().
+ */
+ if (!atomic_dec_and_test(pamt_refcount))
+ return;
+
scoped_guard(spinlock, &pamt_lock) {
- /*
- * If the there are more than 1 references on the pamt page,
- * don't remove it yet. Just decrement the refcount.
- */
- if (atomic_read(pamt_refcount) > 1) {
- atomic_dec(pamt_refcount);
+ /* Lost race with tdx_pamt_get(). */
+ if (atomic_read(pamt_refcount))
return;
- }
/* Try to remove the pamt page and take the refcount 1->0. */
tdx_status = tdh_phymem_pamt_remove(page, pamt_pa_array);
@@ -2233,10 +2264,14 @@ static void tdx_pamt_put(struct page *page)
* failure indicates a kernel bug, memory is being leaked, and
* the dangling PAMT entry may cause future operations to fail.
*/
- if (WARN_ON_ONCE(!IS_TDX_SUCCESS(tdx_status)))
+ if (WARN_ON_ONCE(!IS_TDX_SUCCESS(tdx_status))) {
+ /*
+ * Since the refcount was optimistically decremented above
+ * outside the lock, revert it if there is a failure.
+ */
+ atomic_inc(pamt_refcount);
return;
-
- atomic_dec(pamt_refcount);
+ }
}
/*
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 16/45] x86/virt/tdx: Add tdx_alloc/free_control_page() helpers
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Add helpers to use when allocating or preparing pages that are gifted to
the TDX-Module for use as control/S-EPT pages, and thus need DPAMT backing.
Make them handle races internally for the case of multiple callers trying
operate on the same 2MB range simultaneously.
While the TDX initialization code in arch/x86 uses pages with 2MB
alignment, KVM will need to hand 4KB pages for it to use. Under DPAMT,
these pages will need DPAMT backing 4KB backing.
Add tdx_alloc_control_page() and tdx_free_control_page() to handle both
page allocation and DPAMT installation. Make them behave like normal
alloc/free functions where allocation can fail in the case of no memory,
but free (with any necessary DPAMT release) always succeeds. Do this so
they can support the existing TDX flows that require cleanups to succeed.
Also create tdx_pamt_put()/tdx_pamt_get() to handle installing DPAMT 4KB
backing for pages that are already allocated (such as external page tables,
or S-EPT pages).
Allocate the pages as GFP_KERNEL_ACCOUNT based on that the allocations
will be easily user triggerable.
Since the source of these pages is the page allocator, multiple TDs could
each get 4KB pages that are covered by the same 2MB range. When this
happens only one page pair needs to be installed to cover the 2MB range.
Similarly, when one page is freed, the DPAMT backing cannot be freed until
all TDX pages in the range are no longer in use. Have the helpers manage
these races internally.
So the requirements are that:
1. Free path cannot fail (i.e. no TDX module BUSY errors).
2. Allocation paths need to handle finding that DPAMT backing is already
installed, and only return an error in the case of no memory, not in the
case of losing races with other’s trying to operate on the same DPAMT
range.
3. Free paths cannot fail, and also need to clean up the DPAMT backing
when the last page in the 2MB range is no longer needed by TDX.
Previous changes allocated refcounts to be used to track how many 4KB
pages are in use by TDX for each 2MB region. So update those inside the
helpers and use them to decide when to actually install the DPAMT backing
pages.
tdx_pamt_put() needs to guarantee the DPAMT is installed before returning
so that racing threads don’t tell the TDX module to operate on the page
before it’s installed. Take a lock while adjusting the refcount and doing
the actual TDH.PHYMEM.PAMT.ADD/REMOVE to make sure these happen
atomically. The lock is heavyweight, but will be optimized in future
changes. Just do the simple solution before any complex improvements.
TDH.PHYMEM.PAMT.ADD/REMOVE take exclusive locks at the granularity each
2MB range. A simultaneous attempt to operate on the same 2MB region would
result in a BUSY error code returned from the SEAMCALL. Since the
invocation of SEAMCALLs are behind a lock, this won’t conflict.
Besides the contention between TDH.PHYMEM.PAMT.ADD/REMOVE, many other
SEAMCALLs take the same 2MB granularity locks as shared. This means any
attempt to operate on the page by the TDX module while simultaneously
doing PAMT.ADD/REMOVE will result in a BUSY error. This should not happen,
as the PAMT pages always has to be installed before giving the pages to
the TDX module anyway.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[Add feedback, update log]
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/tdx.h | 24 +++-
arch/x86/virt/vmx/tdx/tdx.c | 264 ++++++++++++++++++++++++++++++++++++
arch/x86/virt/vmx/tdx/tdx.h | 2 +
3 files changed, 289 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 57d5f07e3735..fa29be18498c 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -16,6 +16,7 @@
#include <uapi/asm/mce.h>
#include <asm/tdx_global_metadata.h>
+#include <linux/mm.h>
#include <linux/pgtable.h>
/*
@@ -135,11 +136,32 @@ static inline bool tdx_supports_dynamic_pamt(const struct tdx_sys_info *sysinfo)
return false; /* To be enabled when kernel is ready */
}
+void tdx_quirk_reset_page(struct page *page);
+
int tdx_guest_keyid_alloc(void);
u32 tdx_get_nr_guest_keyids(void);
void tdx_guest_keyid_free(unsigned int keyid);
-void tdx_quirk_reset_page(struct page *page);
+struct page *__tdx_alloc_control_page(gfp_t gfp);
+void __tdx_free_control_page(struct page *page);
+
+static inline unsigned long tdx_alloc_control_page(gfp_t gfp)
+{
+ struct page *page = __tdx_alloc_control_page(gfp);
+
+ if (!page)
+ return 0;
+
+ return (unsigned long)page_address(page);
+}
+
+static inline void tdx_free_control_page(unsigned long addr)
+{
+ if (!addr)
+ return;
+
+ __tdx_free_control_page(virt_to_page(addr));
+}
struct tdx_td {
/* TD root structure: */
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index f6e80aba5895..682c8a228b53 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -1824,6 +1824,50 @@ u64 tdh_mng_rd(struct tdx_td *td, u64 field, u64 *data)
}
EXPORT_SYMBOL_FOR_KVM(tdh_mng_rd);
+/* Number PAMT pages to be provided to TDX module per 2M region of PA */
+static int tdx_dpamt_entry_pages(void)
+{
+ if (!tdx_supports_dynamic_pamt(&tdx_sysinfo))
+ return 0;
+
+ return tdx_sysinfo.tdmr.pamt_4k_entry_size * PTRS_PER_PTE / PAGE_SIZE;
+}
+
+/*
+ * For SEAMCALLs that pass a bundle of pages, the TDX spec treats the registers
+ * like an array, as they are ordered in the struct. The effective array size
+ * is (obviously) limited by the number or registers, relative to the starting
+ * register. Fill the register array at a given starting register, with sanity
+ * checks to avoid overflowing the args structure.
+ */
+static void dpamt_copy_regs_array(struct tdx_module_args *args, void *reg,
+ u64 *pamt_pa_array, bool copy_to_regs)
+{
+ int size = tdx_dpamt_entry_pages() * sizeof(*pamt_pa_array);
+
+ if (WARN_ON_ONCE(reg + size > (void *)args) + sizeof(*args))
+ return;
+
+ /* Copy PAMT page PA's to/from the struct per the TDX ABI. */
+ if (copy_to_regs)
+ memcpy(reg, pamt_pa_array, size);
+ else
+ memcpy(pamt_pa_array, reg, size);
+}
+
+#define dpamt_copy_from_regs(dst, args, reg) \
+ dpamt_copy_regs_array(args, &(args)->reg, dst, false)
+
+#define dpamt_copy_to_regs(args, reg, src) \
+ dpamt_copy_regs_array(args, &(args)->reg, src, true)
+
+/*
+ * When declaring PAMT arrays on the stack, use the maximum theoretical number
+ * of entries that can be squeezed into a SEAMCALL, as stack allocations are
+ * practically free, i.e. any wasted space is a non-issue.
+ */
+#define MAX_NR_DPAMT_ARGS (sizeof(struct tdx_module_args) / sizeof(u64))
+
u64 tdh_mr_extend(struct tdx_td *td, u64 gpa, u64 *ext_err1, u64 *ext_err2)
{
struct tdx_module_args args = {
@@ -2020,6 +2064,226 @@ u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page)
}
EXPORT_SYMBOL_FOR_KVM(tdh_phymem_page_wbinvd_hkid);
+static int alloc_pamt_array(u64 *pa_array)
+{
+ struct page *page;
+ int i;
+
+ for (i = 0; i < tdx_dpamt_entry_pages(); i++) {
+ page = alloc_page(GFP_KERNEL_ACCOUNT);
+ if (!page)
+ goto err;
+ pa_array[i] = page_to_phys(page);
+ }
+
+ return 0;
+err:
+ /*
+ * Zero the rest of the array to help with
+ * freeing in error paths.
+ */
+ for (; i < tdx_dpamt_entry_pages(); i++)
+ pa_array[i] = 0;
+ return -ENOMEM;
+}
+
+static void free_pamt_array(u64 *pa_array)
+{
+ for (int i = 0; i < tdx_dpamt_entry_pages(); i++) {
+ if (!pa_array[i])
+ break;
+
+ /*
+ * Reset pages unconditionally to cover cases
+ * where they were passed to the TDX module.
+ */
+ tdx_quirk_reset_paddr(pa_array[i], PAGE_SIZE);
+
+ __free_page(phys_to_page(pa_array[i]));
+ }
+}
+
+/*
+ * Calculate the arg needed for operating on the DPAMT backing for
+ * a given 4KB page.
+ */
+static u64 pamt_2mb_arg(struct page *page)
+{
+ unsigned long hpa_2mb = ALIGN_DOWN(page_to_phys(page), PMD_SIZE);
+
+ return hpa_2mb | TDX_PS_2M;
+}
+
+/*
+ * Add PAMT backing for the given page. Return's negative error code
+ * for kernel side error conditions (-ENOMEM) and 1 for TDX Module
+ * error. In the case of TDX module error, the return code is stored
+ * in tdx_err.
+ */
+static u64 tdh_phymem_pamt_add(struct page *page, u64 *pamt_pa_array)
+{
+ struct tdx_module_args args = {
+ .rcx = pamt_2mb_arg(page)
+ };
+
+ dpamt_copy_to_regs(&args, rdx, pamt_pa_array);
+
+ return seamcall(TDH_PHYMEM_PAMT_ADD, &args);
+}
+
+/* Remove PAMT backing for the given page. */
+static u64 tdh_phymem_pamt_remove(struct page *page, u64 *pamt_pa_array)
+{
+ struct tdx_module_args args = {
+ .rcx = pamt_2mb_arg(page),
+ };
+ u64 ret;
+
+ ret = seamcall_ret(TDH_PHYMEM_PAMT_REMOVE, &args);
+ if (ret)
+ return ret;
+
+ dpamt_copy_from_regs(pamt_pa_array, &args, rdx);
+ return 0;
+}
+
+/* Serializes adding/removing PAMT memory */
+static DEFINE_SPINLOCK(pamt_lock);
+
+/* Bump PAMT refcount for the given page and allocate PAMT memory if needed */
+static int tdx_pamt_get(struct page *page)
+{
+ u64 pamt_pa_array[MAX_NR_DPAMT_ARGS];
+ atomic_t *pamt_refcount;
+ u64 tdx_status;
+ int ret;
+
+ if (!tdx_supports_dynamic_pamt(&tdx_sysinfo))
+ return 0;
+
+ ret = alloc_pamt_array(pamt_pa_array);
+ if (ret)
+ goto out_free;
+
+ pamt_refcount = tdx_find_pamt_refcount(page_to_pfn(page));
+
+ scoped_guard(spinlock, &pamt_lock) {
+ /*
+ * If the pamt page is already added (i.e. refcount >= 1),
+ * then just increment the refcount.
+ */
+ if (atomic_read(pamt_refcount)) {
+ atomic_inc(pamt_refcount);
+ goto out_free;
+ }
+
+ /* Try to add the pamt page and take the refcount 0->1. */
+ tdx_status = tdh_phymem_pamt_add(page, pamt_pa_array);
+ if (WARN_ON_ONCE(!IS_TDX_SUCCESS(tdx_status))) {
+ ret = -EIO;
+ goto out_free;
+ }
+
+ atomic_inc(pamt_refcount);
+ }
+
+ return 0;
+
+out_free:
+ /*
+ * pamt_pa_array is populated or zeroed up to tdx_dpamt_entry_pages()
+ * above. free_pamt_array() can handle either case.
+ */
+ free_pamt_array(pamt_pa_array);
+ return ret;
+}
+
+/*
+ * Drop PAMT refcount for the given page and free PAMT memory if it is no
+ * longer needed.
+ */
+static void tdx_pamt_put(struct page *page)
+{
+ u64 pamt_pa_array[MAX_NR_DPAMT_ARGS];
+ atomic_t *pamt_refcount;
+ u64 tdx_status;
+
+ if (!tdx_supports_dynamic_pamt(&tdx_sysinfo))
+ return;
+
+ pamt_refcount = tdx_find_pamt_refcount(page_to_pfn(page));
+
+ scoped_guard(spinlock, &pamt_lock) {
+ /*
+ * If the there are more than 1 references on the pamt page,
+ * don't remove it yet. Just decrement the refcount.
+ */
+ if (atomic_read(pamt_refcount) > 1) {
+ atomic_dec(pamt_refcount);
+ return;
+ }
+
+ /* Try to remove the pamt page and take the refcount 1->0. */
+ tdx_status = tdh_phymem_pamt_remove(page, pamt_pa_array);
+
+ /*
+ * Don't free pamt_pa_array as it could hold garbage when
+ * tdh_phymem_pamt_remove() fails. Don't panic/BUG_ON(), as
+ * there is no risk of data corruption, but do yell loudly as
+ * failure indicates a kernel bug, memory is being leaked, and
+ * the dangling PAMT entry may cause future operations to fail.
+ */
+ if (WARN_ON_ONCE(!IS_TDX_SUCCESS(tdx_status)))
+ return;
+
+ atomic_dec(pamt_refcount);
+ }
+
+ /*
+ * pamt_pa_array is populated up to tdx_dpamt_entry_pages() by the TDX
+ * module with pages, or remains zero inited. free_pamt_array() can
+ * handle either case. Just pass it unconditionally.
+ */
+ free_pamt_array(pamt_pa_array);
+}
+
+/*
+ * Return a page that can be gifted to the TDX-Module for use as a "control"
+ * page, i.e. pages that are used for control and S-EPT structures for a given
+ * TDX guest, and bound to said guest's HKID and thus obtain TDX protections,
+ * including PAMT tracking.
+ */
+struct page *__tdx_alloc_control_page(gfp_t gfp)
+{
+ struct page *page;
+
+ page = alloc_page(gfp);
+ if (!page)
+ return NULL;
+
+ if (tdx_pamt_get(page)) {
+ __free_page(page);
+ return NULL;
+ }
+
+ return page;
+}
+EXPORT_SYMBOL_FOR_KVM(__tdx_alloc_control_page);
+
+/*
+ * Free a page that was gifted to the TDX-Module for use as a control/S-EPT
+ * page. After this, the page is no longer protected by TDX.
+ */
+void __tdx_free_control_page(struct page *page)
+{
+ if (!page)
+ return;
+
+ tdx_pamt_put(page);
+ __free_page(page);
+}
+EXPORT_SYMBOL_FOR_KVM(__tdx_free_control_page);
+
#ifdef CONFIG_KEXEC_CORE
void tdx_cpu_flush_cache_for_kexec(void)
{
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index 82bb82be8567..46c4214b79fb 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -46,6 +46,8 @@
#define TDH_PHYMEM_PAGE_WBINVD 41
#define TDH_VP_WR 43
#define TDH_SYS_CONFIG 45
+#define TDH_PHYMEM_PAMT_ADD 58
+#define TDH_PHYMEM_PAMT_REMOVE 59
/*
* SEAMCALL leaf:
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 15/45] x86/virt/tdx: Improve PAMT refcounts allocation for sparse memory
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
init_pamt_metadata() allocates PAMT refcounts for all physical memory up
to max_pfn. It might be suboptimal if the physical memory layout is
discontinuous and has large holes.
The refcount allocation vmalloc allocation. This is necessary to support a
large allocation size. The virtually contiguous property also makes it
easy to find a specific 2MB range’s refcount since it can simply be
indexed.
Since vmalloc mappings support remapping during normal kernel runtime,
switch to an approach that only populates refcount pages for the vmalloc
mapping when there is actually memory for that range. This means any holes
in the physical address space won’t use actual physical memory.
The validity of this memory optimization is based on a couple assumptions:
1. Physical holes in the ram layout are commonly large enough for it to be
worth it.
2. An alternative approach that looks the refcounts via some more layered
data structure wouldn’t overly complicate the lookups. Or at least
more than the complexity of managing the vmalloc mapping.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[Add feedback, update log]
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Tested-by: Sagi Shahar <sagis@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/virt/vmx/tdx/tdx.c | 122 ++++++++++++++++++++++++++++++++++--
1 file changed, 118 insertions(+), 4 deletions(-)
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index db48bf2ce601..f6e80aba5895 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -195,30 +195,135 @@ int tdx_cpu_enable(void)
}
EXPORT_SYMBOL_FOR_KVM(tdx_cpu_enable);
+/* Find PAMT refcount for a given physical address */
+static atomic_t *tdx_find_pamt_refcount(unsigned long pfn)
+{
+ /* Find which PMD a PFN is in. */
+ unsigned long index = pfn >> (PMD_SHIFT - PAGE_SHIFT);
+
+ return &pamt_refcounts[index];
+}
+
+/* Map a page into the PAMT refcount vmalloc region */
+static int pamt_refcount_populate(pte_t *pte, unsigned long addr, void *data)
+{
+ struct page *page;
+ pte_t entry;
+
+ page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+ if (!page)
+ return -ENOMEM;
+
+ entry = mk_pte(page, PAGE_KERNEL);
+
+ spin_lock(&init_mm.page_table_lock);
+ /*
+ * PAMT refcount populations can overlap due to rounding of the
+ * start/end pfn. Make sure the PAMT range is only populated once.
+ */
+ if (pte_none(ptep_get(pte)))
+ set_pte_at(&init_mm, addr, pte, entry);
+ else
+ __free_page(page);
+ spin_unlock(&init_mm.page_table_lock);
+
+ return 0;
+}
+
/*
- * Allocate PAMT reference counters for all physical memory.
+ * Allocate PAMT reference counters for the given PFN range.
*
* It consumes 2MiB for every 1TiB of physical memory.
*/
+static int alloc_pamt_refcount(unsigned long start_pfn, unsigned long end_pfn)
+{
+ unsigned long refcount_first, refcount_last;
+ unsigned long mapping_start, mapping_end;
+
+ if (!tdx_supports_dynamic_pamt(&tdx_sysinfo))
+ return 0;
+
+ /*
+ * 'start_pfn' is inclusive and 'end_pfn' is exclusive. Find the
+ * range of refcounts the pfn range will need.
+ */
+ refcount_first = (unsigned long)tdx_find_pamt_refcount(start_pfn);
+ refcount_last = (unsigned long)tdx_find_pamt_refcount(end_pfn - 1);
+
+ /*
+ * Calculate the page aligned range that includes the refcounts. The
+ * teardown logic needs to handle potentially overlapping refcount
+ * mappings resulting from the alignments.
+ */
+ mapping_start = round_down(refcount_first, PAGE_SIZE);
+ mapping_end = round_up(refcount_last + sizeof(*pamt_refcounts), PAGE_SIZE);
+
+
+ return apply_to_page_range(&init_mm, mapping_start, mapping_end - mapping_start,
+ pamt_refcount_populate, NULL);
+}
+
+/*
+ * Reserve vmalloc range for PAMT reference counters. It covers all physical
+ * address space up to max_pfn. It is going to be populated from
+ * build_tdx_memlist() only for present memory that available for TDX use.
+ *
+ * It reserves 2MiB of virtual address space for every 1TiB of physical memory.
+ */
static int init_pamt_metadata(void)
{
- size_t size = DIV_ROUND_UP(max_pfn, PTRS_PER_PTE) * sizeof(*pamt_refcounts);
+ struct vm_struct *area;
+ size_t size;
if (!tdx_supports_dynamic_pamt(&tdx_sysinfo))
return 0;
- pamt_refcounts = __vmalloc(size, GFP_KERNEL | __GFP_ZERO);
- if (!pamt_refcounts)
+ size = DIV_ROUND_UP(max_pfn, PTRS_PER_PTE) * sizeof(*pamt_refcounts);
+
+ area = get_vm_area(size, VM_SPARSE);
+ if (!area)
return -ENOMEM;
+ pamt_refcounts = area->addr;
return 0;
}
+/* Unmap a page from the PAMT refcount vmalloc region */
+static int pamt_refcount_depopulate(pte_t *pte, unsigned long addr, void *data)
+{
+ struct page *page;
+ pte_t entry;
+
+ spin_lock(&init_mm.page_table_lock);
+
+ entry = ptep_get(pte);
+ /* refcount allocation is sparse, may not be populated */
+ if (!pte_none(entry)) {
+ pte_clear(&init_mm, addr, pte);
+ page = pte_page(entry);
+ __free_page(page);
+ }
+
+ spin_unlock(&init_mm.page_table_lock);
+
+ return 0;
+}
+
+/* Unmap all PAMT refcount pages and free vmalloc range */
static void free_pamt_metadata(void)
{
+ size_t size;
+
if (!tdx_supports_dynamic_pamt(&tdx_sysinfo))
return;
+ size = max_pfn / PTRS_PER_PTE * sizeof(*pamt_refcounts);
+ size = round_up(size, PAGE_SIZE);
+
+ apply_to_existing_page_range(&init_mm,
+ (unsigned long)pamt_refcounts,
+ size, pamt_refcount_depopulate,
+ NULL);
vfree(pamt_refcounts);
pamt_refcounts = NULL;
}
@@ -289,10 +394,19 @@ static int build_tdx_memlist(struct list_head *tmb_list)
ret = add_tdx_memblock(tmb_list, start_pfn, end_pfn, nid);
if (ret)
goto err;
+
+ /* Allocated PAMT refcountes for the memblock */
+ ret = alloc_pamt_refcount(start_pfn, end_pfn);
+ if (ret)
+ goto err;
}
return 0;
err:
+ /*
+ * Only free TDX memory blocks here, PAMT refcount pages
+ * will be freed in the init_tdx_module() error path.
+ */
free_tdx_memlist(tmb_list);
return ret;
}
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 14/45] x86/virt/tdx: Allocate reference counters for PAMT memory
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
The PAMT memory holds metadata for TDX protected memory. With Dynamic
PAMT, the 4KB range of PAMT is allocated on demand. The kernel supplies
the TDX module with a page pair that covers 2MB of host physical memory.
The kernel must provide this page pair before using pages from the range
for TDX. If this is not done, any SEAMCALL that attempts to use the memory
will fail.
Allocate reference counters for every 2MB range to track PAMT memory usage.
This is necessary to accurately determine when PAMT memory needs to be
allocated and when it can be freed.
This allocation will currently consume 2 MB for every 1 TB of address
space from 0 to max_pfn (highest pfn of RAM). The allocation size will
depend on how the ram is physically laid out. In a worse case scenario
where the entire 52 bit address space is covered this would be 8GB. Then
the DPAMT refcount allocations could hypothetically exceed the savings
from Dynamic PAMT, which is 4GB per TB. This is probably unlikely.
However, future changes will reduce this refcount overhead to make DPAMT
always a net win.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[Add feedback, update log]
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Tested-by: Sagi Shahar <sagis@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/virt/vmx/tdx/tdx.c | 47 ++++++++++++++++++++++++++++++++++++-
1 file changed, 46 insertions(+), 1 deletion(-)
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 517c6759c3ca..db48bf2ce601 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -30,6 +30,7 @@
#include <linux/suspend.h>
#include <linux/idr.h>
#include <linux/kvm_types.h>
+#include <linux/vmalloc.h>
#include <asm/page.h>
#include <asm/special_insns.h>
#include <asm/msr-index.h>
@@ -51,6 +52,16 @@ static DEFINE_PER_CPU(bool, tdx_lp_initialized);
static struct tdmr_info_list tdx_tdmr_list;
+/*
+ * On a machine with Dynamic PAMT, the kernel maintains a reference counter
+ * for every 2M range. The counter indicates how many users there are for
+ * the PAMT memory of the 2M range.
+ *
+ * The kernel allocates PAMT memory when the first user arrives and
+ * frees it when the last user has left.
+ */
+static atomic_t *pamt_refcounts;
+
static enum tdx_module_status_t tdx_module_status;
static DEFINE_MUTEX(tdx_module_lock);
@@ -184,6 +195,34 @@ int tdx_cpu_enable(void)
}
EXPORT_SYMBOL_FOR_KVM(tdx_cpu_enable);
+/*
+ * Allocate PAMT reference counters for all physical memory.
+ *
+ * It consumes 2MiB for every 1TiB of physical memory.
+ */
+static int init_pamt_metadata(void)
+{
+ size_t size = DIV_ROUND_UP(max_pfn, PTRS_PER_PTE) * sizeof(*pamt_refcounts);
+
+ if (!tdx_supports_dynamic_pamt(&tdx_sysinfo))
+ return 0;
+
+ pamt_refcounts = __vmalloc(size, GFP_KERNEL | __GFP_ZERO);
+ if (!pamt_refcounts)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static void free_pamt_metadata(void)
+{
+ if (!tdx_supports_dynamic_pamt(&tdx_sysinfo))
+ return;
+
+ vfree(pamt_refcounts);
+ pamt_refcounts = NULL;
+}
+
/*
* Add a memory region as a TDX memory block. The caller must make sure
* all memory regions are added in address ascending order and don't
@@ -1083,10 +1122,14 @@ static int init_tdx_module(void)
*/
get_online_mems();
- ret = build_tdx_memlist(&tdx_memlist);
+ ret = init_pamt_metadata();
if (ret)
goto out_put_tdxmem;
+ ret = build_tdx_memlist(&tdx_memlist);
+ if (ret)
+ goto err_free_pamt_metadata;
+
/* Allocate enough space for constructing TDMRs */
ret = alloc_tdmr_list(&tdx_tdmr_list, &tdx_sysinfo.tdmr);
if (ret)
@@ -1136,6 +1179,8 @@ static int init_tdx_module(void)
free_tdmr_list(&tdx_tdmr_list);
err_free_tdxmem:
free_tdx_memlist(&tdx_memlist);
+err_free_pamt_metadata:
+ free_pamt_metadata();
goto out_put_tdxmem;
}
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 13/45] x86/virt/tdx: Allocate page bitmap for Dynamic PAMT
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
The Physical Address Metadata Table (PAMT) holds TDX metadata for physical
memory and must be allocated by the kernel during TDX module
initialization.
The exact size of the required PAMT memory is determined by the TDX module
and may vary between TDX module versions. Currently it is approximately
0.4% of the system memory. This is a significant commitment, especially if
it is not known upfront whether the machine will run any TDX guests.
For normal PAMT, each memory region that the TDX module might use (TDMR)
needs three separate PAMT allocations. One for each supported page size
(1GB, 2MB, 4KB).
At a high level, Dynamic PAMT still has the 1GB and 2MB levels allocated
on TDX module initialization, but the 4KB level allocated dynamically at
TD runtime. However, in the details, the TDX module still needs some per
4KB page data. The TDX module exposed how many bits per page need to be
allocated (currently it is 1). The bits-per-page value can then be used to
calculate the size to pass in place of the 4KB allocations in the TDMR,
which TDX specs call "PAMT_PAGE_BITMAP".
So in effect, Dynamic PAMT just needs a different (smaller) size
allocation for the 4KB level part of the allocation. Although it is
functionally something different, it is passed in the same way the 4KB page
size PAMT allocation is.
Begin to implement Dynamic PAMT in the kernel by reading the bits-per-page
needed for Dynamic PAMT. Calculate the size needed for the bitmap,
and use it instead of the 4KB size determined for normal PAMT, in the case
of Dynamic PAMT. In doing so, reduce the static allocations to
approximately 0.004%, a 100x improvement.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[Enhanced log]
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Tested-by: Sagi Shahar <sagis@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/tdx.h | 5 +++++
arch/x86/include/asm/tdx_global_metadata.h | 1 +
arch/x86/virt/vmx/tdx/tdx.c | 19 ++++++++++++++++++-
arch/x86/virt/vmx/tdx/tdx_global_metadata.c | 7 +++++++
4 files changed, 31 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 441a26988d3b..57d5f07e3735 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -130,6 +130,11 @@ int tdx_enable(void);
const char *tdx_dump_mce_info(struct mce *m);
const struct tdx_sys_info *tdx_get_sysinfo(void);
+static inline bool tdx_supports_dynamic_pamt(const struct tdx_sys_info *sysinfo)
+{
+ return false; /* To be enabled when kernel is ready */
+}
+
int tdx_guest_keyid_alloc(void);
u32 tdx_get_nr_guest_keyids(void);
void tdx_guest_keyid_free(unsigned int keyid);
diff --git a/arch/x86/include/asm/tdx_global_metadata.h b/arch/x86/include/asm/tdx_global_metadata.h
index 060a2ad744bf..5eb808b23997 100644
--- a/arch/x86/include/asm/tdx_global_metadata.h
+++ b/arch/x86/include/asm/tdx_global_metadata.h
@@ -15,6 +15,7 @@ struct tdx_sys_info_tdmr {
u16 pamt_4k_entry_size;
u16 pamt_2m_entry_size;
u16 pamt_1g_entry_size;
+ u8 pamt_page_bitmap_entry_bits;
};
struct tdx_sys_info_td_ctrl {
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 0c4c873bff80..517c6759c3ca 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -441,6 +441,18 @@ static int fill_out_tdmrs(struct list_head *tmb_list,
return 0;
}
+static unsigned long tdmr_get_pamt_bitmap_sz(struct tdmr_info *tdmr)
+{
+ unsigned long pamt_sz, nr_pamt_entries;
+ int bits_per_entry;
+
+ bits_per_entry = tdx_sysinfo.tdmr.pamt_page_bitmap_entry_bits;
+ nr_pamt_entries = tdmr->size >> PAGE_SHIFT;
+ pamt_sz = DIV_ROUND_UP(nr_pamt_entries * bits_per_entry, BITS_PER_BYTE);
+
+ return PAGE_ALIGN(pamt_sz);
+}
+
/*
* Calculate PAMT size given a TDMR and a page size. The returned
* PAMT size is always aligned up to 4K page boundary.
@@ -508,7 +520,12 @@ static int tdmr_set_up_pamt(struct tdmr_info *tdmr,
* Calculate the PAMT size for each TDX supported page size
* and the total PAMT size.
*/
- tdmr->pamt_4k_size = tdmr_get_pamt_sz(tdmr, TDX_PS_4K);
+ if (tdx_supports_dynamic_pamt(&tdx_sysinfo)) {
+ /* With Dynamic PAMT, PAMT_4K is replaced with a bitmap */
+ tdmr->pamt_4k_size = tdmr_get_pamt_bitmap_sz(tdmr);
+ } else {
+ tdmr->pamt_4k_size = tdmr_get_pamt_sz(tdmr, TDX_PS_4K);
+ }
tdmr->pamt_2m_size = tdmr_get_pamt_sz(tdmr, TDX_PS_2M);
tdmr->pamt_1g_size = tdmr_get_pamt_sz(tdmr, TDX_PS_1G);
tdmr_pamt_size = tdmr->pamt_4k_size + tdmr->pamt_2m_size + tdmr->pamt_1g_size;
diff --git a/arch/x86/virt/vmx/tdx/tdx_global_metadata.c b/arch/x86/virt/vmx/tdx/tdx_global_metadata.c
index 13ad2663488b..00ab0e550636 100644
--- a/arch/x86/virt/vmx/tdx/tdx_global_metadata.c
+++ b/arch/x86/virt/vmx/tdx/tdx_global_metadata.c
@@ -33,6 +33,13 @@ static int get_tdx_sys_info_tdmr(struct tdx_sys_info_tdmr *sysinfo_tdmr)
sysinfo_tdmr->pamt_2m_entry_size = val;
if (!ret && !(ret = read_sys_metadata_field(0x9100000100000012, &val)))
sysinfo_tdmr->pamt_1g_entry_size = val;
+ /*
+ * Don't fail here if tdx_supports_dynamic_pamt() isn't supported. The
+ * TDX code can fallback to normal PAMT if it's not supported.
+ */
+ if (!ret && tdx_supports_dynamic_pamt(&tdx_sysinfo) &&
+ !(ret = read_sys_metadata_field(0x9100000100000013, &val)))
+ sysinfo_tdmr->pamt_page_bitmap_entry_bits = val;
return ret;
}
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 12/45] x86/virt/tdx: Simplify tdmr_get_pamt_sz()
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
From: Rick Edgecombe <rick.p.edgecombe@intel.com>
For each memory region that the TDX module might use (TDMR), the three
separate PAMT allocations are needed. One for each supported page size
(1GB, 2MB, 4KB). These store information on each page in the TDMR. In
Linux, they are allocated out of one physically contiguous block, in order
to more efficiently use some internal TDX module book keeping resources.
So some simple math is needed to break the single large allocation into
three smaller allocations for each page size.
There are some commonalities in the math needed to calculate the base and
size for each smaller allocation, and so an effort was made to share logic
across the three. Unfortunately doing this turned out naturally tortured,
with a loop iterating over the three page sizes, only to call into a
function with a case statement for each page size. In the future Dynamic
PAMT will add more logic that is special to the 4KB page size, making the
benefit of the math sharing even more questionable.
Three is not a very high number, so get rid of the loop and just duplicate
the small calculation three times. In doing so, setup for future Dynamic
PAMT changes and drop a net 33 lines of code.
Since the loop that iterates over it is gone, further simplify the code by
dropping the array of intermediate size and base storage. Just store the
values to their final locations. Accept the small complication of having
to clear tdmr->pamt_4k_base in the error path, so that tdmr_do_pamt_func()
will not try to operate on the TDMR struct when attempting to free it.
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Tested-by: Sagi Shahar <sagis@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/virt/vmx/tdx/tdx.c | 93 ++++++++++++-------------------------
1 file changed, 29 insertions(+), 64 deletions(-)
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 783bf704f2cd..0c4c873bff80 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -445,31 +445,21 @@ static int fill_out_tdmrs(struct list_head *tmb_list,
* Calculate PAMT size given a TDMR and a page size. The returned
* PAMT size is always aligned up to 4K page boundary.
*/
-static unsigned long tdmr_get_pamt_sz(struct tdmr_info *tdmr, int pgsz,
- u16 pamt_entry_size)
+static unsigned long tdmr_get_pamt_sz(struct tdmr_info *tdmr, int pgsz)
{
unsigned long pamt_sz, nr_pamt_entries;
+ const int tdx_pg_size_shift[] = { PAGE_SHIFT, PMD_SHIFT, PUD_SHIFT };
+ const u16 pamt_entry_size[TDX_PS_NR] = {
+ tdx_sysinfo.tdmr.pamt_4k_entry_size,
+ tdx_sysinfo.tdmr.pamt_2m_entry_size,
+ tdx_sysinfo.tdmr.pamt_1g_entry_size,
+ };
- switch (pgsz) {
- case TDX_PS_4K:
- nr_pamt_entries = tdmr->size >> PAGE_SHIFT;
- break;
- case TDX_PS_2M:
- nr_pamt_entries = tdmr->size >> PMD_SHIFT;
- break;
- case TDX_PS_1G:
- nr_pamt_entries = tdmr->size >> PUD_SHIFT;
- break;
- default:
- WARN_ON_ONCE(1);
- return 0;
- }
+ nr_pamt_entries = tdmr->size >> tdx_pg_size_shift[pgsz];
+ pamt_sz = nr_pamt_entries * pamt_entry_size[pgsz];
- pamt_sz = nr_pamt_entries * pamt_entry_size;
/* TDX requires PAMT size must be 4K aligned */
- pamt_sz = ALIGN(pamt_sz, PAGE_SIZE);
-
- return pamt_sz;
+ return PAGE_ALIGN(pamt_sz);
}
/*
@@ -507,28 +497,21 @@ static int tdmr_get_nid(struct tdmr_info *tdmr, struct list_head *tmb_list)
* within @tdmr, and set up PAMTs for @tdmr.
*/
static int tdmr_set_up_pamt(struct tdmr_info *tdmr,
- struct list_head *tmb_list,
- u16 pamt_entry_size[])
+ struct list_head *tmb_list)
{
- unsigned long pamt_base[TDX_PS_NR];
- unsigned long pamt_size[TDX_PS_NR];
- unsigned long tdmr_pamt_base;
unsigned long tdmr_pamt_size;
struct page *pamt;
- int pgsz, nid;
-
+ int nid;
nid = tdmr_get_nid(tdmr, tmb_list);
/*
* Calculate the PAMT size for each TDX supported page size
* and the total PAMT size.
*/
- tdmr_pamt_size = 0;
- for (pgsz = TDX_PS_4K; pgsz < TDX_PS_NR; pgsz++) {
- pamt_size[pgsz] = tdmr_get_pamt_sz(tdmr, pgsz,
- pamt_entry_size[pgsz]);
- tdmr_pamt_size += pamt_size[pgsz];
- }
+ tdmr->pamt_4k_size = tdmr_get_pamt_sz(tdmr, TDX_PS_4K);
+ tdmr->pamt_2m_size = tdmr_get_pamt_sz(tdmr, TDX_PS_2M);
+ tdmr->pamt_1g_size = tdmr_get_pamt_sz(tdmr, TDX_PS_1G);
+ tdmr_pamt_size = tdmr->pamt_4k_size + tdmr->pamt_2m_size + tdmr->pamt_1g_size;
/*
* Allocate one chunk of physically contiguous memory for all
@@ -536,26 +519,18 @@ static int tdmr_set_up_pamt(struct tdmr_info *tdmr,
* in overlapped TDMRs.
*/
pamt = alloc_contig_pages(tdmr_pamt_size >> PAGE_SHIFT, GFP_KERNEL,
- nid, &node_online_map);
- if (!pamt)
+ nid, &node_online_map);
+ if (!pamt) {
+ /*
+ * tdmr->pamt_4k_base is zero so the
+ * error path will skip freeing.
+ */
return -ENOMEM;
-
- /*
- * Break the contiguous allocation back up into the
- * individual PAMTs for each page size.
- */
- tdmr_pamt_base = page_to_pfn(pamt) << PAGE_SHIFT;
- for (pgsz = TDX_PS_4K; pgsz < TDX_PS_NR; pgsz++) {
- pamt_base[pgsz] = tdmr_pamt_base;
- tdmr_pamt_base += pamt_size[pgsz];
}
- tdmr->pamt_4k_base = pamt_base[TDX_PS_4K];
- tdmr->pamt_4k_size = pamt_size[TDX_PS_4K];
- tdmr->pamt_2m_base = pamt_base[TDX_PS_2M];
- tdmr->pamt_2m_size = pamt_size[TDX_PS_2M];
- tdmr->pamt_1g_base = pamt_base[TDX_PS_1G];
- tdmr->pamt_1g_size = pamt_size[TDX_PS_1G];
+ tdmr->pamt_4k_base = page_to_phys(pamt);
+ tdmr->pamt_2m_base = tdmr->pamt_4k_base + tdmr->pamt_4k_size;
+ tdmr->pamt_1g_base = tdmr->pamt_2m_base + tdmr->pamt_2m_size;
return 0;
}
@@ -586,10 +561,7 @@ static void tdmr_do_pamt_func(struct tdmr_info *tdmr,
tdmr_get_pamt(tdmr, &pamt_base, &pamt_size);
/* Do nothing if PAMT hasn't been allocated for this TDMR */
- if (!pamt_size)
- return;
-
- if (WARN_ON_ONCE(!pamt_base))
+ if (!pamt_base)
return;
pamt_func(pamt_base, pamt_size);
@@ -615,14 +587,12 @@ static void tdmrs_free_pamt_all(struct tdmr_info_list *tdmr_list)
/* Allocate and set up PAMTs for all TDMRs */
static int tdmrs_set_up_pamt_all(struct tdmr_info_list *tdmr_list,
- struct list_head *tmb_list,
- u16 pamt_entry_size[])
+ struct list_head *tmb_list)
{
int i, ret = 0;
for (i = 0; i < tdmr_list->nr_consumed_tdmrs; i++) {
- ret = tdmr_set_up_pamt(tdmr_entry(tdmr_list, i), tmb_list,
- pamt_entry_size);
+ ret = tdmr_set_up_pamt(tdmr_entry(tdmr_list, i), tmb_list);
if (ret)
goto err;
}
@@ -903,18 +873,13 @@ static int construct_tdmrs(struct list_head *tmb_list,
struct tdmr_info_list *tdmr_list,
struct tdx_sys_info_tdmr *sysinfo_tdmr)
{
- u16 pamt_entry_size[TDX_PS_NR] = {
- sysinfo_tdmr->pamt_4k_entry_size,
- sysinfo_tdmr->pamt_2m_entry_size,
- sysinfo_tdmr->pamt_1g_entry_size,
- };
int ret;
ret = fill_out_tdmrs(tmb_list, tdmr_list);
if (ret)
return ret;
- ret = tdmrs_set_up_pamt_all(tdmr_list, tmb_list, pamt_entry_size);
+ ret = tdmrs_set_up_pamt_all(tdmr_list, tmb_list);
if (ret)
return ret;
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 11/45] x86/tdx: Add helpers to check return status codes
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
The TDX error code has a complex structure. The upper 32 bits encode the
status code (higher level information), while the lower 32 bits provide
clues about the error, such as operand ID, CPUID leaf, MSR index, etc.
In practice, the kernel logic cares mostly about the status code. Whereas
the error details are more often dumped to warnings to be used as
debugging breadcrumbs. This results in a lot of code that masks the status
code and then checks the resulting value. Future code to support Dynamic
PAMT will add yet more SEAMCALL error code checking. To prepare for this,
do some cleanup to reduce the boiler plate error code parsing.
Since the lower bits that contain details are needed for both error
printing and a few cases where the logical code flow does depend on them,
don’t reduce the boiler plate by masking the detail bits inside the
SEAMCALL wrappers, returning only the status code. Instead, create some
helpers to perform the needed masking and comparisons.
For the status code based checks, create a macro for generating the
helpers based on the name. Name the helpers IS_TDX_FOO(), based on the
discussion in the Link.
Many of the checks that consult the error details are only done in a
single place. It could be argued that there is not any code savings by
adding helpers for these checks. Add helpers for them anyway so that the
checks look consistent when uses with checks that are used in multiple
places (e.g. sc_retry_prerr()).
Finally, update the code that previously open coded the bit math to use
the helpers.
Link: https://lore.kernel.org/kvm/aJNycTvk1GEWgK_Q@google.com/
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[Enhance log]
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Tested-by: Sagi Shahar <sagis@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/coco/tdx/tdx.c | 10 +++---
arch/x86/include/asm/shared/tdx_errno.h | 47 ++++++++++++++++++++++++-
arch/x86/include/asm/tdx.h | 2 +-
arch/x86/kvm/vmx/tdx.c | 40 +++++++++------------
arch/x86/virt/vmx/tdx/tdx.c | 8 ++---
5 files changed, 73 insertions(+), 34 deletions(-)
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index 7b2833705d47..167c5b273c40 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -129,9 +129,9 @@ int tdx_mcall_get_report0(u8 *reportdata, u8 *tdreport)
ret = __tdcall(TDG_MR_REPORT, &args);
if (ret) {
- if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND)
+ if (IS_TDX_OPERAND_INVALID(ret))
return -ENXIO;
- else if (TDCALL_RETURN_CODE(ret) == TDCALL_OPERAND_BUSY)
+ else if (IS_TDX_OPERAND_BUSY(ret))
return -EBUSY;
return -EIO;
}
@@ -165,9 +165,9 @@ int tdx_mcall_extend_rtmr(u8 index, u8 *data)
ret = __tdcall(TDG_MR_RTMR_EXTEND, &args);
if (ret) {
- if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND)
+ if (IS_TDX_OPERAND_INVALID(ret))
return -ENXIO;
- if (TDCALL_RETURN_CODE(ret) == TDCALL_OPERAND_BUSY)
+ if (IS_TDX_OPERAND_BUSY(ret))
return -EBUSY;
return -EIO;
}
@@ -316,7 +316,7 @@ static void reduce_unnecessary_ve(void)
{
u64 err = tdg_vm_wr(TDCS_TD_CTLS, TD_CTLS_REDUCE_VE, TD_CTLS_REDUCE_VE);
- if (err == TDX_SUCCESS)
+ if (IS_TDX_SUCCESS(err))
return;
/*
diff --git a/arch/x86/include/asm/shared/tdx_errno.h b/arch/x86/include/asm/shared/tdx_errno.h
index 3aa74f6a6119..e302aed31b50 100644
--- a/arch/x86/include/asm/shared/tdx_errno.h
+++ b/arch/x86/include/asm/shared/tdx_errno.h
@@ -5,7 +5,7 @@
#include <asm/trapnr.h>
/* Upper 32 bit of the TDX error code encodes the status */
-#define TDX_SEAMCALL_STATUS_MASK 0xFFFFFFFF00000000ULL
+#define TDX_STATUS_MASK 0xFFFFFFFF00000000ULL
/*
* TDX SEAMCALL Status Codes
@@ -54,4 +54,49 @@
#define TDX_OPERAND_ID_SEPT 0x92
#define TDX_OPERAND_ID_TD_EPOCH 0xa9
+#ifndef __ASSEMBLER__
+#include <linux/bits.h>
+#include <linux/types.h>
+
+static inline u64 TDX_STATUS(u64 err)
+{
+ return err & TDX_STATUS_MASK;
+}
+
+static inline bool IS_TDX_NON_RECOVERABLE(u64 err)
+{
+ return (err & TDX_NON_RECOVERABLE) == TDX_NON_RECOVERABLE;
+}
+
+static inline bool IS_TDX_SEAMCALL_VMFAILINVALID(u64 err)
+{
+ return (err & TDX_SEAMCALL_VMFAILINVALID) ==
+ TDX_SEAMCALL_VMFAILINVALID;
+}
+
+static inline bool IS_TDX_SEAMCALL_GP(u64 err)
+{
+ return err == TDX_SEAMCALL_GP;
+}
+
+static inline bool IS_TDX_SEAMCALL_UD(u64 err)
+{
+ return err == TDX_SEAMCALL_UD;
+}
+
+#define DEFINE_TDX_ERRNO_HELPER(error) \
+ static inline bool IS_##error(u64 err) \
+ { \
+ return TDX_STATUS(err) == error; \
+ }
+
+DEFINE_TDX_ERRNO_HELPER(TDX_SUCCESS);
+DEFINE_TDX_ERRNO_HELPER(TDX_RND_NO_ENTROPY);
+DEFINE_TDX_ERRNO_HELPER(TDX_OPERAND_INVALID);
+DEFINE_TDX_ERRNO_HELPER(TDX_OPERAND_BUSY);
+DEFINE_TDX_ERRNO_HELPER(TDX_VCPU_NOT_ASSOCIATED);
+DEFINE_TDX_ERRNO_HELPER(TDX_FLUSHVP_NOT_DONE);
+DEFINE_TDX_ERRNO_HELPER(TDX_SW_ERROR);
+
+#endif /* __ASSEMBLER__ */
#endif /* _X86_SHARED_TDX_ERRNO_H */
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index c3c574511094..441a26988d3b 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -117,7 +117,7 @@ static __always_inline u64 sc_retry(sc_func_t func, u64 fn,
preempt_disable();
ret = __seamcall_dirty_cache(func, fn, args);
preempt_enable();
- } while (ret == TDX_RND_NO_ENTROPY && --retry);
+ } while (IS_TDX_RND_NO_ENTROPY(ret) && --retry);
return ret;
}
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 66bc3ceb5e17..4ef414ee27b4 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -220,12 +220,6 @@ static DEFINE_MUTEX(tdx_lock);
static atomic_t nr_configured_hkid;
-static bool tdx_operand_busy(u64 err)
-{
- return (err & TDX_SEAMCALL_STATUS_MASK) == TDX_OPERAND_BUSY;
-}
-
-
/*
* A per-CPU list of TD vCPUs associated with a given CPU.
* Protected by interrupt mask. Only manipulated by the CPU owning this per-CPU
@@ -312,7 +306,7 @@ static inline void tdx_disassociate_vp(struct kvm_vcpu *vcpu)
lockdep_assert_held_write(&kvm->mmu_lock); \
\
__err = tdh_func(args); \
- if (unlikely(tdx_operand_busy(__err))) { \
+ if (unlikely(IS_TDX_OPERAND_BUSY(__err))) { \
WRITE_ONCE(__kvm_tdx->wait_for_sept_zap, true); \
kvm_make_all_cpus_request(kvm, KVM_REQ_OUTSIDE_GUEST_MODE); \
\
@@ -400,7 +394,7 @@ static void tdx_flush_vp(void *_arg)
* migration. No other thread uses TDVPR in those cases.
*/
err = tdh_vp_flush(&to_tdx(vcpu)->vp);
- if (unlikely(err && err != TDX_VCPU_NOT_ASSOCIATED)) {
+ if (unlikely(!IS_TDX_VCPU_NOT_ASSOCIATED(err))) {
/*
* This function is called in IPI context. Do not use
* printk to avoid console semaphore.
@@ -467,7 +461,7 @@ static void smp_func_do_phymem_cache_wb(void *unused)
/*
* TDH.PHYMEM.CACHE.WB flushes caches associated with any TDX private
* KeyID on the package or core. The TDX module may not finish the
- * cache flush but return TDX_INTERRUPTED_RESUMEABLE instead. The
+ * cache flush but return TDX_ERR_INTERRUPTED_RESUMEABLE instead. The
* kernel should retry it until it returns success w/o rescheduling.
*/
for (i = TDX_SEAMCALL_RETRIES; i > 0; i--) {
@@ -522,7 +516,7 @@ void tdx_mmu_release_hkid(struct kvm *kvm)
* associations, as all vCPU fds have been released at this stage.
*/
err = tdh_mng_vpflushdone(&kvm_tdx->td);
- if (err == TDX_FLUSHVP_NOT_DONE)
+ if (IS_TDX_FLUSHVP_NOT_DONE(err))
goto out;
if (TDX_BUG_ON(err, TDH_MNG_VPFLUSHDONE, kvm)) {
pr_err("tdh_mng_vpflushdone() failed. HKID %d is leaked.\n",
@@ -937,7 +931,7 @@ static __always_inline u32 tdx_to_vmx_exit_reason(struct kvm_vcpu *vcpu)
struct vcpu_tdx *tdx = to_tdx(vcpu);
u32 exit_reason;
- switch (tdx->vp_enter_ret & TDX_SEAMCALL_STATUS_MASK) {
+ switch (TDX_STATUS(tdx->vp_enter_ret)) {
case TDX_SUCCESS:
case TDX_NON_RECOVERABLE_VCPU:
case TDX_NON_RECOVERABLE_TD:
@@ -1011,7 +1005,7 @@ static fastpath_t tdx_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
* EXIT_FASTPATH_REENTER_GUEST to exit fastpath, otherwise, the
* requester may be blocked endlessly.
*/
- if (unlikely(tdx_operand_busy(vp_enter_ret)))
+ if (unlikely(IS_TDX_OPERAND_BUSY(vp_enter_ret)))
return EXIT_FASTPATH_EXIT_HANDLED;
return EXIT_FASTPATH_NONE;
@@ -1107,7 +1101,7 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, u64 run_flags)
if (unlikely(tdx->vp_enter_ret == EXIT_REASON_EPT_MISCONFIG))
return EXIT_FASTPATH_NONE;
- if (unlikely((tdx->vp_enter_ret & TDX_SW_ERROR) == TDX_SW_ERROR))
+ if (unlikely(IS_TDX_SW_ERROR(tdx->vp_enter_ret)))
return EXIT_FASTPATH_NONE;
trace_kvm_exit(vcpu, KVM_ISA_VMX);
@@ -1636,7 +1630,7 @@ static int tdx_mem_page_add(struct kvm *kvm, gfn_t gfn, enum pg_level level,
err = tdh_mem_page_add(&kvm_tdx->td, gpa, pfn_to_page(pfn),
kvm_tdx->page_add_src, &entry, &level_state);
- if (unlikely(tdx_operand_busy(err)))
+ if (unlikely(IS_TDX_OPERAND_BUSY(err)))
return -EBUSY;
if (TDX_BUG_ON_2(err, TDH_MEM_PAGE_ADD, entry, level_state, kvm))
@@ -1655,7 +1649,7 @@ static int tdx_mem_page_aug(struct kvm *kvm, gfn_t gfn,
u64 err;
err = tdh_mem_page_aug(&kvm_tdx->td, gpa, level, page, &entry, &level_state);
- if (unlikely(tdx_operand_busy(err)))
+ if (unlikely(IS_TDX_OPERAND_BUSY(err)))
return -EBUSY;
if (TDX_BUG_ON_2(err, TDH_MEM_PAGE_AUG, entry, level_state, kvm))
@@ -1690,7 +1684,7 @@ static int tdx_sept_link_private_spt(struct kvm *kvm, gfn_t gfn,
err = tdh_mem_sept_add(&to_kvm_tdx(kvm)->td, gpa, level, external_spt,
&entry, &level_state);
- if (unlikely(tdx_operand_busy(err)))
+ if (unlikely(IS_TDX_OPERAND_BUSY(err)))
return -EBUSY;
if (TDX_BUG_ON_2(err, TDH_MEM_SEPT_ADD, entry, level_state, kvm))
@@ -2011,7 +2005,7 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
* Handle TDX SW errors, including TDX_SEAMCALL_UD, TDX_SEAMCALL_GP and
* TDX_SEAMCALL_VMFAILINVALID.
*/
- if (unlikely((vp_enter_ret & TDX_SW_ERROR) == TDX_SW_ERROR)) {
+ if (unlikely(IS_TDX_SW_ERROR(vp_enter_ret))) {
KVM_BUG_ON(!kvm_rebooting, vcpu->kvm);
goto unhandled_exit;
}
@@ -2022,7 +2016,7 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
* not enabled, TDX_NON_RECOVERABLE must be set.
*/
WARN_ON_ONCE(vcpu->arch.guest_state_protected &&
- !(vp_enter_ret & TDX_NON_RECOVERABLE));
+ !IS_TDX_NON_RECOVERABLE(vp_enter_ret));
vcpu->run->exit_reason = KVM_EXIT_FAIL_ENTRY;
vcpu->run->fail_entry.hardware_entry_failure_reason = exit_reason.full;
vcpu->run->fail_entry.cpu = vcpu->arch.last_vmentry_cpu;
@@ -2036,7 +2030,7 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
}
WARN_ON_ONCE(exit_reason.basic != EXIT_REASON_TRIPLE_FAULT &&
- (vp_enter_ret & TDX_SEAMCALL_STATUS_MASK) != TDX_SUCCESS);
+ !IS_TDX_SUCCESS(vp_enter_ret));
switch (exit_reason.basic) {
case EXIT_REASON_TRIPLE_FAULT:
@@ -2470,7 +2464,7 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
err = tdh_mng_create(&kvm_tdx->td, kvm_tdx->hkid);
mutex_unlock(&tdx_lock);
- if (err == TDX_RND_NO_ENTROPY) {
+ if (IS_TDX_RND_NO_ENTROPY(err)) {
ret = -EAGAIN;
goto free_packages;
}
@@ -2511,7 +2505,7 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
kvm_tdx->td.tdcs_pages = tdcs_pages;
for (i = 0; i < kvm_tdx->td.tdcs_nr_pages; i++) {
err = tdh_mng_addcx(&kvm_tdx->td, tdcs_pages[i]);
- if (err == TDX_RND_NO_ENTROPY) {
+ if (IS_TDX_RND_NO_ENTROPY(err)) {
/* Here it's hard to allow userspace to retry. */
ret = -EAGAIN;
goto teardown;
@@ -2523,7 +2517,7 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
}
err = tdh_mng_init(&kvm_tdx->td, __pa(td_params), &rcx);
- if ((err & TDX_SEAMCALL_STATUS_MASK) == TDX_OPERAND_INVALID) {
+ if (IS_TDX_OPERAND_INVALID(err)) {
/*
* Because a user gives operands, don't warn.
* Return a hint to the user because it's sometimes hard for the
@@ -2837,7 +2831,7 @@ static int tdx_td_finalize(struct kvm *kvm, struct kvm_tdx_cmd *cmd)
return -EINVAL;
cmd->hw_error = tdh_mr_finalize(&kvm_tdx->td);
- if (tdx_operand_busy(cmd->hw_error))
+ if (IS_TDX_OPERAND_BUSY(cmd->hw_error))
return -EBUSY;
if (TDX_BUG_ON(cmd->hw_error, TDH_MR_FINALIZE, kvm))
return -EIO;
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 22c0f832cb37..783bf704f2cd 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -82,16 +82,16 @@ static __always_inline int sc_retry_prerr(sc_func_t func,
{
u64 sret = sc_retry(func, fn, args);
- if (sret == TDX_SUCCESS)
+ if (IS_TDX_SUCCESS(sret))
return 0;
- if (sret == TDX_SEAMCALL_VMFAILINVALID)
+ if (IS_TDX_SEAMCALL_VMFAILINVALID(sret))
return -ENODEV;
- if (sret == TDX_SEAMCALL_GP)
+ if (IS_TDX_SEAMCALL_GP(sret))
return -EOPNOTSUPP;
- if (sret == TDX_SEAMCALL_UD)
+ if (IS_TDX_SEAMCALL_UD(sret))
return -EACCES;
err_func(fn, sret, args);
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 10/45] x86/tdx: Move all TDX error defines into <asm/shared/tdx_errno.h>
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Today there are two separate locations where TDX error codes are defined:
arch/x86/include/asm/tdx.h
arch/x86/kvm/vmx/tdx_errno.h
They have some overlap that is already defined similarly. Reduce the
duplication and prepare to introduce some helpers for these error codes in
the central place by unifying them. Join them at:
asm/shared/tdx_errno.h
...and update the headers that contained the duplicated definitions to
include the new unified header.
"asm/shared" is used for sharing TDX code between the early compressed
code and the normal kernel code. While the compressed code for the guest
doesn't use these error code header definitions today, it does make the
types of calls that return the values they define. So place the defines in
"shared" location so that it can, but leave such cleanups for future
changes.
Opportunistically massage some comments. Also, adjust
_BITUL()->_BITULL() to address 32 bit build errors after the move.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[enhance log]
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Tested-by: Sagi Shahar <sagis@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/shared/tdx.h | 1 +
.../vmx => include/asm/shared}/tdx_errno.h | 27 +++++++++++++++----
arch/x86/include/asm/tdx.h | 20 --------------
arch/x86/kvm/vmx/tdx.h | 1 -
4 files changed, 23 insertions(+), 26 deletions(-)
rename arch/x86/{kvm/vmx => include/asm/shared}/tdx_errno.h (65%)
diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
index 8bc074c8d7c6..6a1646fc2b2f 100644
--- a/arch/x86/include/asm/shared/tdx.h
+++ b/arch/x86/include/asm/shared/tdx.h
@@ -4,6 +4,7 @@
#include <linux/bits.h>
#include <linux/types.h>
+#include <asm/shared/tdx_errno.h>
#define TDX_HYPERCALL_STANDARD 0
diff --git a/arch/x86/kvm/vmx/tdx_errno.h b/arch/x86/include/asm/shared/tdx_errno.h
similarity index 65%
rename from arch/x86/kvm/vmx/tdx_errno.h
rename to arch/x86/include/asm/shared/tdx_errno.h
index 6ff4672c4181..3aa74f6a6119 100644
--- a/arch/x86/kvm/vmx/tdx_errno.h
+++ b/arch/x86/include/asm/shared/tdx_errno.h
@@ -1,14 +1,16 @@
/* SPDX-License-Identifier: GPL-2.0 */
-/* architectural status code for SEAMCALL */
+#ifndef _X86_SHARED_TDX_ERRNO_H
+#define _X86_SHARED_TDX_ERRNO_H
-#ifndef __KVM_X86_TDX_ERRNO_H
-#define __KVM_X86_TDX_ERRNO_H
+#include <asm/trapnr.h>
+/* Upper 32 bit of the TDX error code encodes the status */
#define TDX_SEAMCALL_STATUS_MASK 0xFFFFFFFF00000000ULL
/*
- * TDX SEAMCALL Status Codes (returned in RAX)
+ * TDX SEAMCALL Status Codes
*/
+#define TDX_SUCCESS 0ULL
#define TDX_NON_RECOVERABLE_VCPU 0x4000000100000000ULL
#define TDX_NON_RECOVERABLE_TD 0x4000000200000000ULL
#define TDX_NON_RECOVERABLE_TD_NON_ACCESSIBLE 0x6000000500000000ULL
@@ -17,6 +19,7 @@
#define TDX_OPERAND_INVALID 0xC000010000000000ULL
#define TDX_OPERAND_BUSY 0x8000020000000000ULL
#define TDX_PREVIOUS_TLB_EPOCH_BUSY 0x8000020100000000ULL
+#define TDX_RND_NO_ENTROPY 0x8000020300000000ULL
#define TDX_PAGE_METADATA_INCORRECT 0xC000030000000000ULL
#define TDX_VCPU_NOT_ASSOCIATED 0x8000070200000000ULL
#define TDX_KEY_GENERATION_FAILED 0x8000080000000000ULL
@@ -28,6 +31,20 @@
#define TDX_EPT_ENTRY_STATE_INCORRECT 0xC0000B0D00000000ULL
#define TDX_METADATA_FIELD_NOT_READABLE 0xC0000C0200000000ULL
+/*
+ * SW-defined error codes.
+ *
+ * Bits 47:40 == 0xFF indicate Reserved status code class that never used by
+ * TDX module.
+ */
+#define TDX_ERROR _BITULL(63)
+#define TDX_NON_RECOVERABLE _BITULL(62)
+#define TDX_SW_ERROR (TDX_ERROR | GENMASK_ULL(47, 40))
+#define TDX_SEAMCALL_VMFAILINVALID (TDX_SW_ERROR | _ULL(0xFFFF0000))
+
+#define TDX_SEAMCALL_GP (TDX_SW_ERROR | X86_TRAP_GP)
+#define TDX_SEAMCALL_UD (TDX_SW_ERROR | X86_TRAP_UD)
+
/*
* TDX module operand ID, appears in 31:0 part of error code as
* detail information
@@ -37,4 +54,4 @@
#define TDX_OPERAND_ID_SEPT 0x92
#define TDX_OPERAND_ID_TD_EPOCH 0xa9
-#endif /* __KVM_X86_TDX_ERRNO_H */
+#endif /* _X86_SHARED_TDX_ERRNO_H */
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index bc0d03e70fd6..c3c574511094 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -12,26 +12,6 @@
#include <asm/trapnr.h>
#include <asm/shared/tdx.h>
-/*
- * SW-defined error codes.
- *
- * Bits 47:40 == 0xFF indicate Reserved status code class that never used by
- * TDX module.
- */
-#define TDX_ERROR _BITUL(63)
-#define TDX_NON_RECOVERABLE _BITUL(62)
-#define TDX_SW_ERROR (TDX_ERROR | GENMASK_ULL(47, 40))
-#define TDX_SEAMCALL_VMFAILINVALID (TDX_SW_ERROR | _UL(0xFFFF0000))
-
-#define TDX_SEAMCALL_GP (TDX_SW_ERROR | X86_TRAP_GP)
-#define TDX_SEAMCALL_UD (TDX_SW_ERROR | X86_TRAP_UD)
-
-/*
- * TDX module SEAMCALL leaf function error codes
- */
-#define TDX_SUCCESS 0ULL
-#define TDX_RND_NO_ENTROPY 0x8000020300000000ULL
-
#ifndef __ASSEMBLER__
#include <uapi/asm/mce.h>
diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h
index 45b5183ccb36..ce2720a028ad 100644
--- a/arch/x86/kvm/vmx/tdx.h
+++ b/arch/x86/kvm/vmx/tdx.h
@@ -3,7 +3,6 @@
#define __KVM_X86_VMX_TDX_H
#include "tdx_arch.h"
-#include "tdx_errno.h"
#ifdef CONFIG_KVM_INTEL_TDX
#include "common.h"
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 09/45] KVM: x86: Rework .free_external_spt() into .reclaim_external_sp()
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
Massage .free_external_spt() into .reclaim_external_sp() to free up (pun
intended) "free" for actually freeing memory, and to allow TDX to do more
than just "free" the S-EPT entry. Specifically, nullify external_spt to
leak the S-EPT page if reclaiming the page fails, as that detail and
implementation choice has no business living in the TDP MMU.
Use "sp" instead of "spt" even though "spt" is arguably more accurate, as
"spte" and "spt" are dangerously close in name, and because the key
parameter is a kvm_mmu_page, not a pointer to an S-EPT page table.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/kvm-x86-ops.h | 2 +-
arch/x86/include/asm/kvm_host.h | 4 ++--
arch/x86/kvm/mmu/tdp_mmu.c | 13 ++-----------
arch/x86/kvm/vmx/tdx.c | 27 ++++++++++++---------------
4 files changed, 17 insertions(+), 29 deletions(-)
diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 57eb1f4832ae..c17cedc485c9 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -95,8 +95,8 @@ KVM_X86_OP_OPTIONAL_RET0(set_identity_map_addr)
KVM_X86_OP_OPTIONAL_RET0(get_mt_mask)
KVM_X86_OP(load_mmu_pgd)
KVM_X86_OP_OPTIONAL_RET0(set_external_spte)
-KVM_X86_OP_OPTIONAL_RET0(free_external_spt)
KVM_X86_OP_OPTIONAL(remove_external_spte)
+KVM_X86_OP_OPTIONAL(reclaim_external_sp)
KVM_X86_OP(has_wbinvd_exit)
KVM_X86_OP(get_l2_tsc_offset)
KVM_X86_OP(get_l2_tsc_multiplier)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index d12ca0f8a348..b35a07ed11fb 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1858,8 +1858,8 @@ struct kvm_x86_ops {
u64 mirror_spte);
/* Update external page tables for page table about to be freed. */
- int (*free_external_spt)(struct kvm *kvm, gfn_t gfn, enum pg_level level,
- void *external_spt);
+ void (*reclaim_external_sp)(struct kvm *kvm, gfn_t gfn,
+ struct kvm_mmu_page *sp);
/* Update external page table from spte getting removed, and flush TLB. */
void (*remove_external_spte)(struct kvm *kvm, gfn_t gfn, enum pg_level level,
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 27ac520f2a89..18764dbc97ea 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -456,17 +456,8 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)
old_spte, FROZEN_SPTE, level, shared);
}
- if (is_mirror_sp(sp) &&
- WARN_ON(kvm_x86_call(free_external_spt)(kvm, base_gfn, sp->role.level,
- sp->external_spt))) {
- /*
- * Failed to free page table page in mirror page table and
- * there is nothing to do further.
- * Intentionally leak the page to prevent the kernel from
- * accessing the encrypted page.
- */
- sp->external_spt = NULL;
- }
+ if (is_mirror_sp(sp))
+ kvm_x86_call(reclaim_external_sp)(kvm, base_gfn, sp);
call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback);
}
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 30494f9ceb31..66bc3ceb5e17 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1783,27 +1783,24 @@ static void tdx_track(struct kvm *kvm)
kvm_make_all_cpus_request(kvm, KVM_REQ_OUTSIDE_GUEST_MODE);
}
-static int tdx_sept_free_private_spt(struct kvm *kvm, gfn_t gfn,
- enum pg_level level, void *private_spt)
+static void tdx_sept_reclaim_private_sp(struct kvm *kvm, gfn_t gfn,
+ struct kvm_mmu_page *sp)
{
- struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
-
/*
- * free_external_spt() is only called after hkid is freed when TD is
- * tearing down.
* KVM doesn't (yet) zap page table pages in mirror page table while
* TD is active, though guest pages mapped in mirror page table could be
* zapped during TD is active, e.g. for shared <-> private conversion
* and slot move/deletion.
+ *
+ * In other words, KVM should only free mirror page tables after the
+ * TD's hkid is freed, when the TD is being torn down.
+ *
+ * If the S-EPT PTE can't be removed for any reason, intentionally leak
+ * the page to prevent the kernel from accessing the encrypted page.
*/
- if (KVM_BUG_ON(is_hkid_assigned(kvm_tdx), kvm))
- return -EIO;
-
- /*
- * The HKID assigned to this TD was already freed and cache was
- * already flushed. We don't have to flush again.
- */
- return tdx_reclaim_page(virt_to_page(private_spt));
+ if (KVM_BUG_ON(is_hkid_assigned(to_kvm_tdx(kvm)), kvm) ||
+ tdx_reclaim_page(virt_to_page(sp->external_spt)))
+ sp->external_spt = NULL;
}
static void tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn,
@@ -3617,7 +3614,7 @@ void __init tdx_hardware_setup(void)
vt_x86_ops.vm_size = max_t(unsigned int, vt_x86_ops.vm_size, sizeof(struct kvm_tdx));
vt_x86_ops.set_external_spte = tdx_sept_set_private_spte;
- vt_x86_ops.free_external_spt = tdx_sept_free_private_spt;
+ vt_x86_ops.reclaim_external_sp = tdx_sept_reclaim_private_sp;
vt_x86_ops.remove_external_spte = tdx_sept_remove_private_spte;
vt_x86_ops.protected_apic_has_interrupt = tdx_protected_apic_has_interrupt;
}
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 08/45] KVM: x86/mmu: Propagate mirror SPTE removal to S-EPT in handle_changed_spte()
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
Invoke .remove_external_spte() in handle_changed_spte() as appropriate
instead of relying on callers to do the right thing. Relying on callers
to invoke .remove_external_spte() is confusing and brittle, e.g. subtly
relies tdp_mmu_set_spte_atomic() never removing SPTEs, and removing an
S-EPT entry in tdp_mmu_set_spte() is bizarre (yeah, the VM is bugged so
it doesn't matter in practice, but it's still weird).
Implementing rules-based logic in a common chokepoint will also make it
easier to reason about the correctness of splitting hugepages when support
for S-EPT hugepages comes along.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/mmu/tdp_mmu.c | 43 +++++++++++++-------------------------
1 file changed, 14 insertions(+), 29 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 8743cd020d12..27ac520f2a89 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -359,25 +359,6 @@ static void tdp_mmu_unlink_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
spin_unlock(&kvm->arch.tdp_mmu_pages_lock);
}
-static void remove_external_spte(struct kvm *kvm, gfn_t gfn, u64 old_spte,
- int level)
-{
- /*
- * External (TDX) SPTEs are limited to PG_LEVEL_4K, and external
- * PTs are removed in a special order, involving free_external_spt().
- * But remove_external_spte() will be called on non-leaf PTEs via
- * __tdp_mmu_zap_root(), so avoid the error the former would return
- * in this case.
- */
- if (!is_last_spte(old_spte, level))
- return;
-
- /* Zapping leaf spte is allowed only when write lock is held. */
- lockdep_assert_held_write(&kvm->mmu_lock);
-
- kvm_x86_call(remove_external_spte)(kvm, gfn, level, old_spte);
-}
-
/**
* handle_removed_pt() - handle a page table removed from the TDP structure
*
@@ -473,11 +454,6 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)
}
handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), sptep, gfn,
old_spte, FROZEN_SPTE, level, shared);
-
- if (is_mirror_sp(sp)) {
- KVM_BUG_ON(shared, kvm);
- remove_external_spte(kvm, gfn, old_spte, level);
- }
}
if (is_mirror_sp(sp) &&
@@ -590,10 +566,21 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep,
* the paging structure. Note the WARN on the PFN changing without the
* SPTE being converted to a hugepage (leaf) or being zapped. Shadow
* pages are kernel allocations and should never be migrated.
+ *
+ * When removing leaf entries from a mirror, immediately propagate the
+ * changes to the external page tables. Note, non-leaf mirror entries
+ * are handled by handle_removed_pt(), as TDX requires that all leaf
+ * entries are removed before the owning page table. Note #2, writes
+ * to make mirror PTEs shadow-present are propagated to external page
+ * tables by __tdp_mmu_set_spte_atomic(), as KVM needs to ensure the
+ * external page table was successfully updated before marking the
+ * mirror SPTE present.
*/
if (was_present && !was_leaf &&
(is_leaf || !is_present || WARN_ON_ONCE(pfn_changed)))
handle_removed_pt(kvm, spte_to_child_pt(old_spte, level), shared);
+ else if (was_leaf && is_mirror_sptep(sptep) && !is_leaf)
+ kvm_x86_call(remove_external_spte)(kvm, gfn, level, old_spte);
}
static inline int __must_check __tdp_mmu_set_spte_atomic(struct kvm *kvm,
@@ -725,12 +712,10 @@ static u64 tdp_mmu_set_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep,
/*
* Users that do non-atomic setting of PTEs don't operate on mirror
- * roots, so don't handle it and bug the VM if it's seen.
+ * roots. Bug the VM as this path doesn't propagate such writes to the
+ * external page tables.
*/
- if (is_mirror_sptep(sptep)) {
- KVM_BUG_ON(is_shadow_present_pte(new_spte), kvm);
- remove_external_spte(kvm, gfn, old_spte, level);
- }
+ KVM_BUG_ON(is_mirror_sptep(sptep) && is_shadow_present_pte(new_spte), kvm);
return old_spte;
}
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 07/45] KVM: x86/mmu: Plumb the SPTE _pointer_ into the TDP MMU's handle_changed_spte()
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
Plumb the SPTE pointer into handle_changed_spte() so that remove leaf
mirror entries can be forwarded to TDX in handle_changed_spte(), instead
of effectively requiring callers to manually do so. Relying on each
caller to invoke .remove_external_spte() is confusing and brittle, e.g.
subtly relies tdp_mmu_set_spte_atomic() never removing SPTEs. This will
also allow consolidating all S-EPT updates into a single kvm_x86_ops hook.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/mmu/tdp_mmu.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 6fb48b217f5b..8743cd020d12 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -320,9 +320,9 @@ void kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu, bool mirror)
}
}
-static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
- u64 old_spte, u64 new_spte, int level,
- bool shared);
+static void handle_changed_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep,
+ gfn_t gfn, u64 old_spte, u64 new_spte,
+ int level, bool shared);
static void tdp_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp)
{
@@ -471,7 +471,7 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)
old_spte = kvm_tdp_mmu_write_spte(sptep, old_spte,
FROZEN_SPTE, level);
}
- handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn,
+ handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), sptep, gfn,
old_spte, FROZEN_SPTE, level, shared);
if (is_mirror_sp(sp)) {
@@ -499,6 +499,7 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)
* handle_changed_spte - handle bookkeeping associated with an SPTE change
* @kvm: kvm instance
* @as_id: the address space of the paging structure the SPTE was a part of
+ * @sptep: pointer to the SPTE
* @gfn: the base GFN that was mapped by the SPTE
* @old_spte: The value of the SPTE before the change
* @new_spte: The value of the SPTE after the change
@@ -511,9 +512,9 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)
* dirty logging updates are handled in common code, not here (see make_spte()
* and fast_pf_fix_direct_spte()).
*/
-static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
- u64 old_spte, u64 new_spte, int level,
- bool shared)
+static void handle_changed_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep,
+ gfn_t gfn, u64 old_spte, u64 new_spte,
+ int level, bool shared)
{
bool was_present = is_shadow_present_pte(old_spte);
bool is_present = is_shadow_present_pte(new_spte);
@@ -685,8 +686,8 @@ static inline int __must_check tdp_mmu_set_spte_atomic(struct kvm *kvm,
if (ret)
return ret;
- handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte,
- new_spte, iter->level, true);
+ handle_changed_spte(kvm, iter->as_id, iter->sptep, iter->gfn,
+ iter->old_spte, new_spte, iter->level, true);
return 0;
}
@@ -720,7 +721,7 @@ static u64 tdp_mmu_set_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep,
old_spte = kvm_tdp_mmu_write_spte(sptep, old_spte, new_spte, level);
- handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level, false);
+ handle_changed_spte(kvm, as_id, sptep, gfn, old_spte, new_spte, level, false);
/*
* Users that do non-atomic setting of PTEs don't operate on mirror
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 06/45] KVM: x86/mmu: Fold set_external_spte_present() into its sole caller
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
Fold set_external_spte_present() into __tdp_mmu_set_spte_atomic() in
anticipation of supporting hugepage splitting, at which point other paths
will also set shadow-present external SPTEs.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/mmu/tdp_mmu.c | 82 +++++++++++++++++---------------------
1 file changed, 36 insertions(+), 46 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 56ad056e6042..6fb48b217f5b 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -495,33 +495,6 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)
call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback);
}
-static int __must_check set_external_spte_present(struct kvm *kvm, tdp_ptep_t sptep,
- gfn_t gfn, u64 *old_spte,
- u64 new_spte, int level)
-{
- int ret;
-
- lockdep_assert_held(&kvm->mmu_lock);
-
- if (KVM_BUG_ON(is_shadow_present_pte(*old_spte), kvm))
- return -EIO;
-
- /*
- * We need to lock out other updates to the SPTE until the external
- * page table has been modified. Use FROZEN_SPTE similar to
- * the zapping case.
- */
- if (!try_cmpxchg64(rcu_dereference(sptep), old_spte, FROZEN_SPTE))
- return -EBUSY;
-
- ret = kvm_x86_call(set_external_spte)(kvm, gfn, level, new_spte);
- if (ret)
- __kvm_tdp_mmu_write_spte(sptep, *old_spte);
- else
- __kvm_tdp_mmu_write_spte(sptep, new_spte);
- return ret;
-}
-
/**
* handle_changed_spte - handle bookkeeping associated with an SPTE change
* @kvm: kvm instance
@@ -626,6 +599,8 @@ static inline int __must_check __tdp_mmu_set_spte_atomic(struct kvm *kvm,
struct tdp_iter *iter,
u64 new_spte)
{
+ u64 *raw_sptep = rcu_dereference(iter->sptep);
+
/*
* The caller is responsible for ensuring the old SPTE is not a FROZEN
* SPTE. KVM should never attempt to zap or manipulate a FROZEN SPTE,
@@ -638,31 +613,46 @@ static inline int __must_check __tdp_mmu_set_spte_atomic(struct kvm *kvm,
int ret;
/*
- * Users of atomic zapping don't operate on mirror roots,
- * so don't handle it and bug the VM if it's seen.
+ * KVM doesn't currently support zapping or splitting mirror
+ * SPTEs while holding mmu_lock for read.
*/
- if (KVM_BUG_ON(!is_shadow_present_pte(new_spte), kvm))
+ if (KVM_BUG_ON(is_shadow_present_pte(iter->old_spte), kvm) ||
+ KVM_BUG_ON(!is_shadow_present_pte(new_spte), kvm))
return -EBUSY;
- ret = set_external_spte_present(kvm, iter->sptep, iter->gfn,
- &iter->old_spte, new_spte, iter->level);
+ /*
+ * Temporarily freeze the SPTE until the external PTE operation
+ * has completed, e.g. so that concurrent faults don't attempt
+ * to install a child PTE in the external page table before the
+ * parent PTE has been written.
+ */
+ if (!try_cmpxchg64(raw_sptep, &iter->old_spte, FROZEN_SPTE))
+ return -EBUSY;
+
+ /*
+ * Update the external PTE. On success, set the mirror SPTE to
+ * the desired value. On failure, restore the old SPTE so that
+ * the SPTE isn't frozen in perpetuity.
+ */
+ ret = kvm_x86_call(set_external_spte)(kvm, iter->gfn,
+ iter->level, new_spte);
if (ret)
- return ret;
- } else {
- u64 *sptep = rcu_dereference(iter->sptep);
-
- /*
- * Note, fast_pf_fix_direct_spte() can also modify TDP MMU SPTEs
- * and does not hold the mmu_lock. On failure, i.e. if a
- * different logical CPU modified the SPTE, try_cmpxchg64()
- * updates iter->old_spte with the current value, so the caller
- * operates on fresh data, e.g. if it retries
- * tdp_mmu_set_spte_atomic()
- */
- if (!try_cmpxchg64(sptep, &iter->old_spte, new_spte))
- return -EBUSY;
+ __kvm_tdp_mmu_write_spte(iter->sptep, iter->old_spte);
+ else
+ __kvm_tdp_mmu_write_spte(iter->sptep, new_spte);
+ return ret;
}
+ /*
+ * Note, fast_pf_fix_direct_spte() can also modify TDP MMU SPTEs and
+ * does not hold the mmu_lock. On failure, i.e. if a different logical
+ * CPU modified the SPTE, try_cmpxchg64() updates iter->old_spte with
+ * the current value, so the caller operates on fresh data, e.g. if it
+ * retries tdp_mmu_set_spte_atomic()
+ */
+ if (!try_cmpxchg64(raw_sptep, &iter->old_spte, new_spte))
+ return -EBUSY;
+
return 0;
}
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 05/45] KVM: TDX: Drop kvm_x86_ops.link_external_spt(), use .set_external_spte() for all
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
Drop the dedicated .link_external_spt() for linking non-leaf S-EPT pages,
and instead funnel everything through .set_external_spte(). Using separate
hooks doesn't help prevent TDP MMU details from bleeding into TDX, and vice
versa; to the contrary, dedicated callbacks will result in _more_ pollution
when hugepage support is added, e.g. will require the TDP MMU to know
details about the splitting rules for TDX that aren't all that relevant to
the TDP MMU.
Ideally, KVM would provide a single pair of hooks to set S-EPT entries,
one hook for setting SPTEs under write-lock and another for settings SPTEs
under read-lock (e.g. to ensure the entire operation is "atomic", to allow
for failure, etc.). Sadly, TDX's requirement that all child S-EPT entries
are removed before the parent makes that impractical: the TDP MMU
deliberately prunes non-leaf SPTEs and _then_ processes its children, thus
making it quite important for the TDP MMU to differentiate between zapping
leaf and non-leaf S-EPT entries.
However, that's the _only_ case that's truly special, and even that case
could be shoehorned into a single hook; it's just wouldn't be a net
positive.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/kvm-x86-ops.h | 1 -
arch/x86/include/asm/kvm_host.h | 3 --
arch/x86/kvm/mmu/tdp_mmu.c | 37 +++---------------
arch/x86/kvm/vmx/tdx.c | 61 ++++++++++++++++++++----------
4 files changed, 48 insertions(+), 54 deletions(-)
diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index c18a033bee7e..57eb1f4832ae 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -94,7 +94,6 @@ KVM_X86_OP_OPTIONAL_RET0(set_tss_addr)
KVM_X86_OP_OPTIONAL_RET0(set_identity_map_addr)
KVM_X86_OP_OPTIONAL_RET0(get_mt_mask)
KVM_X86_OP(load_mmu_pgd)
-KVM_X86_OP_OPTIONAL_RET0(link_external_spt)
KVM_X86_OP_OPTIONAL_RET0(set_external_spte)
KVM_X86_OP_OPTIONAL_RET0(free_external_spt)
KVM_X86_OP_OPTIONAL(remove_external_spte)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index e441f270f354..d12ca0f8a348 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1853,9 +1853,6 @@ struct kvm_x86_ops {
void (*load_mmu_pgd)(struct kvm_vcpu *vcpu, hpa_t root_hpa,
int root_level);
- /* Update external mapping with page table link. */
- int (*link_external_spt)(struct kvm *kvm, gfn_t gfn, enum pg_level level,
- void *external_spt);
/* Update the external page table from spte getting set. */
int (*set_external_spte)(struct kvm *kvm, gfn_t gfn, enum pg_level level,
u64 mirror_spte);
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 0feda295859a..56ad056e6042 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -495,31 +495,17 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)
call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback);
}
-static void *get_external_spt(gfn_t gfn, u64 new_spte, int level)
-{
- if (is_shadow_present_pte(new_spte) && !is_last_spte(new_spte, level)) {
- struct kvm_mmu_page *sp = spte_to_child_sp(new_spte);
-
- WARN_ON_ONCE(sp->role.level + 1 != level);
- WARN_ON_ONCE(sp->gfn != gfn);
- return sp->external_spt;
- }
-
- return NULL;
-}
-
static int __must_check set_external_spte_present(struct kvm *kvm, tdp_ptep_t sptep,
gfn_t gfn, u64 *old_spte,
u64 new_spte, int level)
{
- bool was_present = is_shadow_present_pte(*old_spte);
- bool is_present = is_shadow_present_pte(new_spte);
- bool is_leaf = is_present && is_last_spte(new_spte, level);
- int ret = 0;
-
- KVM_BUG_ON(was_present, kvm);
+ int ret;
lockdep_assert_held(&kvm->mmu_lock);
+
+ if (KVM_BUG_ON(is_shadow_present_pte(*old_spte), kvm))
+ return -EIO;
+
/*
* We need to lock out other updates to the SPTE until the external
* page table has been modified. Use FROZEN_SPTE similar to
@@ -528,18 +514,7 @@ static int __must_check set_external_spte_present(struct kvm *kvm, tdp_ptep_t sp
if (!try_cmpxchg64(rcu_dereference(sptep), old_spte, FROZEN_SPTE))
return -EBUSY;
- /*
- * Use different call to either set up middle level
- * external page table, or leaf.
- */
- if (is_leaf) {
- ret = kvm_x86_call(set_external_spte)(kvm, gfn, level, new_spte);
- } else {
- void *external_spt = get_external_spt(gfn, new_spte, level);
-
- KVM_BUG_ON(!external_spt, kvm);
- ret = kvm_x86_call(link_external_spt)(kvm, gfn, level, external_spt);
- }
+ ret = kvm_x86_call(set_external_spte)(kvm, gfn, level, new_spte);
if (ret)
__kvm_tdp_mmu_write_spte(sptep, *old_spte);
else
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 5688c77616e3..30494f9ceb31 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1664,18 +1664,58 @@ static int tdx_mem_page_aug(struct kvm *kvm, gfn_t gfn,
return 0;
}
+static struct page *tdx_spte_to_external_spt(struct kvm *kvm, gfn_t gfn,
+ u64 new_spte, enum pg_level level)
+{
+ struct kvm_mmu_page *sp = spte_to_child_sp(new_spte);
+
+ if (KVM_BUG_ON(!sp->external_spt, kvm) ||
+ KVM_BUG_ON(sp->role.level + 1 != level, kvm) ||
+ KVM_BUG_ON(sp->gfn != gfn, kvm))
+ return NULL;
+
+ return virt_to_page(sp->external_spt);
+}
+
+static int tdx_sept_link_private_spt(struct kvm *kvm, gfn_t gfn,
+ enum pg_level level, u64 mirror_spte)
+{
+ gpa_t gpa = gfn_to_gpa(gfn);
+ u64 err, entry, level_state;
+ struct page *external_spt;
+
+ external_spt = tdx_spte_to_external_spt(kvm, gfn, mirror_spte, level);
+ if (!external_spt)
+ return -EIO;
+
+ err = tdh_mem_sept_add(&to_kvm_tdx(kvm)->td, gpa, level, external_spt,
+ &entry, &level_state);
+ if (unlikely(tdx_operand_busy(err)))
+ return -EBUSY;
+
+ if (TDX_BUG_ON_2(err, TDH_MEM_SEPT_ADD, entry, level_state, kvm))
+ return -EIO;
+
+ return 0;
+}
+
static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
enum pg_level level, u64 mirror_spte)
{
struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
kvm_pfn_t pfn = spte_to_pfn(mirror_spte);
+ if (KVM_BUG_ON(!is_shadow_present_pte(mirror_spte), kvm))
+ return -EIO;
+
+ if (!is_last_spte(mirror_spte, level))
+ return tdx_sept_link_private_spt(kvm, gfn, level, mirror_spte);
+
/* TODO: handle large pages. */
if (KVM_BUG_ON(level != PG_LEVEL_4K, kvm))
return -EIO;
- WARN_ON_ONCE(!is_shadow_present_pte(mirror_spte) ||
- (mirror_spte & VMX_EPT_RWX_MASK) != VMX_EPT_RWX_MASK);
+ WARN_ON_ONCE((mirror_spte & VMX_EPT_RWX_MASK) != VMX_EPT_RWX_MASK);
/*
* Ensure pre_fault_allowed is read by kvm_arch_vcpu_pre_fault_memory()
@@ -1695,23 +1735,7 @@ static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
return tdx_mem_page_aug(kvm, gfn, level, pfn);
}
-static int tdx_sept_link_private_spt(struct kvm *kvm, gfn_t gfn,
- enum pg_level level, void *private_spt)
-{
- gpa_t gpa = gfn_to_gpa(gfn);
- struct page *page = virt_to_page(private_spt);
- u64 err, entry, level_state;
- err = tdh_mem_sept_add(&to_kvm_tdx(kvm)->td, gpa, level, page, &entry,
- &level_state);
- if (unlikely(tdx_operand_busy(err)))
- return -EBUSY;
-
- if (TDX_BUG_ON_2(err, TDH_MEM_SEPT_ADD, entry, level_state, kvm))
- return -EIO;
-
- return 0;
-}
/*
* Ensure shared and private EPTs to be flushed on all vCPUs.
@@ -3592,7 +3616,6 @@ void __init tdx_hardware_setup(void)
*/
vt_x86_ops.vm_size = max_t(unsigned int, vt_x86_ops.vm_size, sizeof(struct kvm_tdx));
- vt_x86_ops.link_external_spt = tdx_sept_link_private_spt;
vt_x86_ops.set_external_spte = tdx_sept_set_private_spte;
vt_x86_ops.free_external_spt = tdx_sept_free_private_spt;
vt_x86_ops.remove_external_spte = tdx_sept_remove_private_spte;
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 04/45] KVM: x86: Make "external SPTE" ops that can fail RET0 static calls
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
Define kvm_x86_ops .link_external_spt(), .set_external_spte(), and
.free_external_spt() as RET0 static calls so that an unexpected call to a
a default operation doesn't consume garbage.
Fixes: 77ac7079e66d ("KVM: x86/tdp_mmu: Propagate building mirror page tables")
Fixes: 94faba8999b9 ("KVM: x86/tdp_mmu: Propagate tearing down mirror page tables")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/kvm-x86-ops.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index de709fb5bd76..c18a033bee7e 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -94,9 +94,9 @@ KVM_X86_OP_OPTIONAL_RET0(set_tss_addr)
KVM_X86_OP_OPTIONAL_RET0(set_identity_map_addr)
KVM_X86_OP_OPTIONAL_RET0(get_mt_mask)
KVM_X86_OP(load_mmu_pgd)
-KVM_X86_OP_OPTIONAL(link_external_spt)
-KVM_X86_OP_OPTIONAL(set_external_spte)
-KVM_X86_OP_OPTIONAL(free_external_spt)
+KVM_X86_OP_OPTIONAL_RET0(link_external_spt)
+KVM_X86_OP_OPTIONAL_RET0(set_external_spte)
+KVM_X86_OP_OPTIONAL_RET0(free_external_spt)
KVM_X86_OP_OPTIONAL(remove_external_spte)
KVM_X86_OP(has_wbinvd_exit)
KVM_X86_OP(get_l2_tsc_offset)
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 03/45] KVM: TDX: Account all non-transient page allocations for per-TD structures
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
Account all non-transient allocations associated with a single TD (or its
vCPUs), as KVM's ABI is that allocations that are active for the lifetime
of a VM are accounted. Leave temporary allocations, i.e. allocations that
are freed within a single function/ioctl, unaccounted, to again align with
KVM's existing behavior, e.g. see commit dd103407ca31 ("KVM: X86: Remove
unnecessary GFP_KERNEL_ACCOUNT for temporary variables").
Fixes: 8d032b683c29 ("KVM: TDX: create/destroy VM structure")
Fixes: a50f673f25e0 ("KVM: TDX: Do TDX specific vcpu initialization")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/vmx/tdx.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 561461c9d131..5688c77616e3 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -2397,7 +2397,7 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
atomic_inc(&nr_configured_hkid);
- tdr_page = alloc_page(GFP_KERNEL);
+ tdr_page = alloc_page(GFP_KERNEL_ACCOUNT);
if (!tdr_page)
goto free_hkid;
@@ -2405,12 +2405,12 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
/* TDVPS = TDVPR(4K page) + TDCX(multiple 4K pages), -1 for TDVPR. */
kvm_tdx->td.tdcx_nr_pages = tdx_sysinfo->td_ctrl.tdvps_base_size / PAGE_SIZE - 1;
tdcs_pages = kcalloc(kvm_tdx->td.tdcs_nr_pages, sizeof(*kvm_tdx->td.tdcs_pages),
- GFP_KERNEL);
+ GFP_KERNEL_ACCOUNT);
if (!tdcs_pages)
goto free_tdr;
for (i = 0; i < kvm_tdx->td.tdcs_nr_pages; i++) {
- tdcs_pages[i] = alloc_page(GFP_KERNEL);
+ tdcs_pages[i] = alloc_page(GFP_KERNEL_ACCOUNT);
if (!tdcs_pages[i])
goto free_tdcs;
}
@@ -2885,7 +2885,7 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
int ret, i;
u64 err;
- page = alloc_page(GFP_KERNEL);
+ page = alloc_page(GFP_KERNEL_ACCOUNT);
if (!page)
return -ENOMEM;
tdx->vp.tdvpr_page = page;
@@ -2898,14 +2898,14 @@ static int tdx_td_vcpu_init(struct kvm_vcpu *vcpu, u64 vcpu_rcx)
tdx->vp.tdvpr_pa = page_to_phys(tdx->vp.tdvpr_page);
tdx->vp.tdcx_pages = kcalloc(kvm_tdx->td.tdcx_nr_pages, sizeof(*tdx->vp.tdcx_pages),
- GFP_KERNEL);
+ GFP_KERNEL_ACCOUNT);
if (!tdx->vp.tdcx_pages) {
ret = -ENOMEM;
goto free_tdvpr;
}
for (i = 0; i < kvm_tdx->td.tdcx_nr_pages; i++) {
- page = alloc_page(GFP_KERNEL);
+ page = alloc_page(GFP_KERNEL_ACCOUNT);
if (!page) {
ret = -ENOMEM;
goto free_tdcx;
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 02/45] KVM: x86/mmu: Update iter->old_spte if cmpxchg64 on mirror SPTE "fails"
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
Pass a pointer to iter->old_spte, not simply its value, when setting an
external SPTE in __tdp_mmu_set_spte_atomic(), so that the iterator's value
will be updated if the cmpxchg64 to freeze the mirror SPTE fails. The bug
is currently benign as TDX is mutualy exclusive with all paths that do
"local" retry", e.g. clear_dirty_gfn_range() and wrprot_gfn_range().
Fixes: 77ac7079e66d ("KVM: x86/tdp_mmu: Propagate building mirror page tables")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/mmu/tdp_mmu.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 9c26038f6b77..0feda295859a 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -509,10 +509,10 @@ static void *get_external_spt(gfn_t gfn, u64 new_spte, int level)
}
static int __must_check set_external_spte_present(struct kvm *kvm, tdp_ptep_t sptep,
- gfn_t gfn, u64 old_spte,
+ gfn_t gfn, u64 *old_spte,
u64 new_spte, int level)
{
- bool was_present = is_shadow_present_pte(old_spte);
+ bool was_present = is_shadow_present_pte(*old_spte);
bool is_present = is_shadow_present_pte(new_spte);
bool is_leaf = is_present && is_last_spte(new_spte, level);
int ret = 0;
@@ -525,7 +525,7 @@ static int __must_check set_external_spte_present(struct kvm *kvm, tdp_ptep_t sp
* page table has been modified. Use FROZEN_SPTE similar to
* the zapping case.
*/
- if (!try_cmpxchg64(rcu_dereference(sptep), &old_spte, FROZEN_SPTE))
+ if (!try_cmpxchg64(rcu_dereference(sptep), old_spte, FROZEN_SPTE))
return -EBUSY;
/*
@@ -541,7 +541,7 @@ static int __must_check set_external_spte_present(struct kvm *kvm, tdp_ptep_t sp
ret = kvm_x86_call(link_external_spt)(kvm, gfn, level, external_spt);
}
if (ret)
- __kvm_tdp_mmu_write_spte(sptep, old_spte);
+ __kvm_tdp_mmu_write_spte(sptep, *old_spte);
else
__kvm_tdp_mmu_write_spte(sptep, new_spte);
return ret;
@@ -670,7 +670,7 @@ static inline int __must_check __tdp_mmu_set_spte_atomic(struct kvm *kvm,
return -EBUSY;
ret = set_external_spte_present(kvm, iter->sptep, iter->gfn,
- iter->old_spte, new_spte, iter->level);
+ &iter->old_spte, new_spte, iter->level);
if (ret)
return ret;
} else {
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 01/45] x86/tdx: Use pg_level in TDX APIs, not the TDX-Module's 0-based level
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
In-Reply-To: <20260129011517.3545883-1-seanjc@google.com>
Rework the TDX APIs to take the kernel's 1-based pg_level enum, not the
TDX-Module's 0-based level. The APIs are _kernel_ APIs, not TDX-Module
APIs, and the kernel (and KVM) uses "enum pg_level" literally everywhere.
Using "enum pg_level" eliminates ambiguity when looking at the APIs (it's
NOT clear that "int level" refers to the TDX-Module's level), and will
allow for using existing helpers like page_level_size() when support for
hugepages is added to the S-EPT APIs.
No functional change intended.
Cc: Kai Huang <kai.huang@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Yan Zhao <yan.y.zhao@intel.com>
Cc: Vishal Annapurve <vannapurve@google.com>
Cc: Ackerley Tng <ackerleytng@google.com>
Acked-by: Kiryl Shutsemau <kas@kernel.org>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Tested-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/tdx.h | 14 ++++----------
arch/x86/kvm/vmx/tdx.c | 11 ++++-------
arch/x86/virt/vmx/tdx/tdx.c | 26 ++++++++++++++++++--------
3 files changed, 26 insertions(+), 25 deletions(-)
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 6b338d7f01b7..bc0d03e70fd6 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -189,19 +189,13 @@ static inline u64 mk_keyed_paddr(u16 hkid, struct page *page)
return ret;
}
-static inline int pg_level_to_tdx_sept_level(enum pg_level level)
-{
- WARN_ON_ONCE(level == PG_LEVEL_NONE);
- return level - 1;
-}
-
u64 tdh_vp_enter(struct tdx_vp *vp, struct tdx_module_args *args);
u64 tdh_mng_addcx(struct tdx_td *td, struct page *tdcs_page);
u64 tdh_mem_page_add(struct tdx_td *td, u64 gpa, struct page *page, struct page *source, u64 *ext_err1, u64 *ext_err2);
-u64 tdh_mem_sept_add(struct tdx_td *td, u64 gpa, int level, struct page *page, u64 *ext_err1, u64 *ext_err2);
+u64 tdh_mem_sept_add(struct tdx_td *td, u64 gpa, enum pg_level level, struct page *page, u64 *ext_err1, u64 *ext_err2);
u64 tdh_vp_addcx(struct tdx_vp *vp, struct page *tdcx_page);
-u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, int level, struct page *page, u64 *ext_err1, u64 *ext_err2);
-u64 tdh_mem_range_block(struct tdx_td *td, u64 gpa, int level, u64 *ext_err1, u64 *ext_err2);
+u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, enum pg_level level, struct page *page, u64 *ext_err1, u64 *ext_err2);
+u64 tdh_mem_range_block(struct tdx_td *td, u64 gpa, enum pg_level level, u64 *ext_err1, u64 *ext_err2);
u64 tdh_mng_key_config(struct tdx_td *td);
u64 tdh_mng_create(struct tdx_td *td, u16 hkid);
u64 tdh_vp_create(struct tdx_td *td, struct tdx_vp *vp);
@@ -217,7 +211,7 @@ u64 tdh_vp_rd(struct tdx_vp *vp, u64 field, u64 *data);
u64 tdh_vp_wr(struct tdx_vp *vp, u64 field, u64 data, u64 mask);
u64 tdh_phymem_page_reclaim(struct page *page, u64 *tdx_pt, u64 *tdx_owner, u64 *tdx_size);
u64 tdh_mem_track(struct tdx_td *tdr);
-u64 tdh_mem_page_remove(struct tdx_td *td, u64 gpa, u64 level, u64 *ext_err1, u64 *ext_err2);
+u64 tdh_mem_page_remove(struct tdx_td *td, u64 gpa, enum pg_level level, u64 *ext_err1, u64 *ext_err2);
u64 tdh_phymem_cache_wb(bool resume);
u64 tdh_phymem_page_wbinvd_tdr(struct tdx_td *td);
u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page);
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 5df9d32d2058..561461c9d131 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1648,14 +1648,13 @@ static int tdx_mem_page_add(struct kvm *kvm, gfn_t gfn, enum pg_level level,
static int tdx_mem_page_aug(struct kvm *kvm, gfn_t gfn,
enum pg_level level, kvm_pfn_t pfn)
{
- int tdx_level = pg_level_to_tdx_sept_level(level);
struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
struct page *page = pfn_to_page(pfn);
gpa_t gpa = gfn_to_gpa(gfn);
u64 entry, level_state;
u64 err;
- err = tdh_mem_page_aug(&kvm_tdx->td, gpa, tdx_level, page, &entry, &level_state);
+ err = tdh_mem_page_aug(&kvm_tdx->td, gpa, level, page, &entry, &level_state);
if (unlikely(tdx_operand_busy(err)))
return -EBUSY;
@@ -1699,12 +1698,11 @@ static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
static int tdx_sept_link_private_spt(struct kvm *kvm, gfn_t gfn,
enum pg_level level, void *private_spt)
{
- int tdx_level = pg_level_to_tdx_sept_level(level);
gpa_t gpa = gfn_to_gpa(gfn);
struct page *page = virt_to_page(private_spt);
u64 err, entry, level_state;
- err = tdh_mem_sept_add(&to_kvm_tdx(kvm)->td, gpa, tdx_level, page, &entry,
+ err = tdh_mem_sept_add(&to_kvm_tdx(kvm)->td, gpa, level, page, &entry,
&level_state);
if (unlikely(tdx_operand_busy(err)))
return -EBUSY;
@@ -1788,7 +1786,6 @@ static void tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn,
enum pg_level level, u64 mirror_spte)
{
struct page *page = pfn_to_page(spte_to_pfn(mirror_spte));
- int tdx_level = pg_level_to_tdx_sept_level(level);
struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
gpa_t gpa = gfn_to_gpa(gfn);
u64 err, entry, level_state;
@@ -1808,7 +1805,7 @@ static void tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn,
return;
err = tdh_do_no_vcpus(tdh_mem_range_block, kvm, &kvm_tdx->td, gpa,
- tdx_level, &entry, &level_state);
+ level, &entry, &level_state);
if (TDX_BUG_ON_2(err, TDH_MEM_RANGE_BLOCK, entry, level_state, kvm))
return;
@@ -1824,7 +1821,7 @@ static void tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn,
* Race with TDH.VP.ENTER due to (0-step mitigation) and Guest TDCALLs.
*/
err = tdh_do_no_vcpus(tdh_mem_page_remove, kvm, &kvm_tdx->td, gpa,
- tdx_level, &entry, &level_state);
+ level, &entry, &level_state);
if (TDX_BUG_ON_2(err, TDH_MEM_PAGE_REMOVE, entry, level_state, kvm))
return;
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 5ce4ebe99774..22c0f832cb37 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -1516,6 +1516,12 @@ static void tdx_clflush_page(struct page *page)
clflush_cache_range(page_to_virt(page), PAGE_SIZE);
}
+static int pg_level_to_tdx_sept_level(enum pg_level level)
+{
+ WARN_ON_ONCE(level == PG_LEVEL_NONE);
+ return level - 1;
+}
+
noinstr u64 tdh_vp_enter(struct tdx_vp *td, struct tdx_module_args *args)
{
args->rcx = td->tdvpr_pa;
@@ -1556,10 +1562,11 @@ u64 tdh_mem_page_add(struct tdx_td *td, u64 gpa, struct page *page, struct page
}
EXPORT_SYMBOL_FOR_KVM(tdh_mem_page_add);
-u64 tdh_mem_sept_add(struct tdx_td *td, u64 gpa, int level, struct page *page, u64 *ext_err1, u64 *ext_err2)
+u64 tdh_mem_sept_add(struct tdx_td *td, u64 gpa, enum pg_level level,
+ struct page *page, u64 *ext_err1, u64 *ext_err2)
{
struct tdx_module_args args = {
- .rcx = gpa | level,
+ .rcx = gpa | pg_level_to_tdx_sept_level(level),
.rdx = tdx_tdr_pa(td),
.r8 = page_to_phys(page),
};
@@ -1587,10 +1594,11 @@ u64 tdh_vp_addcx(struct tdx_vp *vp, struct page *tdcx_page)
}
EXPORT_SYMBOL_FOR_KVM(tdh_vp_addcx);
-u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, int level, struct page *page, u64 *ext_err1, u64 *ext_err2)
+u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, enum pg_level level,
+ struct page *page, u64 *ext_err1, u64 *ext_err2)
{
struct tdx_module_args args = {
- .rcx = gpa | level,
+ .rcx = gpa | pg_level_to_tdx_sept_level(level),
.rdx = tdx_tdr_pa(td),
.r8 = page_to_phys(page),
};
@@ -1606,10 +1614,11 @@ u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, int level, struct page *page, u
}
EXPORT_SYMBOL_FOR_KVM(tdh_mem_page_aug);
-u64 tdh_mem_range_block(struct tdx_td *td, u64 gpa, int level, u64 *ext_err1, u64 *ext_err2)
+u64 tdh_mem_range_block(struct tdx_td *td, u64 gpa, enum pg_level level,
+ u64 *ext_err1, u64 *ext_err2)
{
struct tdx_module_args args = {
- .rcx = gpa | level,
+ .rcx = gpa | pg_level_to_tdx_sept_level(level),
.rdx = tdx_tdr_pa(td),
};
u64 ret;
@@ -1822,10 +1831,11 @@ u64 tdh_mem_track(struct tdx_td *td)
}
EXPORT_SYMBOL_FOR_KVM(tdh_mem_track);
-u64 tdh_mem_page_remove(struct tdx_td *td, u64 gpa, u64 level, u64 *ext_err1, u64 *ext_err2)
+u64 tdh_mem_page_remove(struct tdx_td *td, u64 gpa, enum pg_level level,
+ u64 *ext_err1, u64 *ext_err2)
{
struct tdx_module_args args = {
- .rcx = gpa | level,
+ .rcx = gpa | pg_level_to_tdx_sept_level(level),
.rdx = tdx_tdr_pa(td),
};
u64 ret;
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply related
* [RFC PATCH v5 00/45] TDX: Dynamic PAMT + S-EPT Hugepage
From: Sean Christopherson @ 2026-01-29 1:14 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Kiryl Shutsemau, Sean Christopherson, Paolo Bonzini
Cc: linux-kernel, linux-coco, kvm, Kai Huang, Rick Edgecombe,
Yan Zhao, Vishal Annapurve, Ackerley Tng, Sagi Shahar, Binbin Wu,
Xiaoyao Li, Isaku Yamahata
This is a combined series of Dynamic PAMT (from Rick), and S-EPT hugepage
support (from Yan). Except for some last minute tweaks to the DPAMT array
args stuff, a version of this based on a Google-internal kernel has been
moderately well tested (thanks Vishal!). But overall it's still firmly RFC
as I have deliberately NOT addressed others feedback from v4 of DPAMT and v3
of S-EPT hugepage (mostly lack of cycles), and there's at least one patch in
here that shouldn't be merged as-is (the quick-and-dirty switch from struct
page to raw pfns).
My immediate goal is to solidify the designs for DPAMT and S-EPT hugepage.
Given the substantial design changes I am proposing, posting an end-to-end
RFC seemed like a much better method than trying to communicate my thoughts
piecemeal.
As for landing these series, I think the fastest overall approach would be
to land patches 1-4 asap (tangentially related cleanups and fixes), agree
on a design (hopefully), and then hand control back to Rick and Yan to polish
their respective series for merge.
I also want to land the VMXON series[*] before DPAMT, because there's a nasty
wart where KVM wires up a DPAMT-specific hook even if DPAMT is disabled,
because KVM's ordering needs to set the vendor hooks before tdx_sysinfo is
ready. Decoupling VMXON from KVM solves that problem, because it lets the
TDX subsystem parse sysinfo before TDX is loaded.
Beyond that dependency, I am comfortable landing both DPAMT and S-EPT hugepage
support without any other prereqs, i.e. without an in-tree way to light up
the S-EPT hugepage code due to lack of hugepage support in guest_memfd.
Outside of the guest_memfd arch hook for in-place conversion, S-EPT hugepage
support doesn't have any direction dependencies/conflicts with guest_memfd
hugepage or in-place conversion support (which is great, because it means we
didn't totally botch the design!). E.g. Vishal's been able to test this code
precisely because it applies relatively cleanly on an internal branch with a
whole pile of guest_memfd changes.
Applies on kvm-x86 next (specifically kvm-x86-next-2026.01.23).
[*] https://lore.kernel.org/all/20251206011054.494190-1-seanjc@google.com
P.S. I apologize if I clobbered any of the Author attribution or SoBs. I
was moving patches around and synchronizing between an internal tree
and this upstream version, so things may have gotten a bit wonky.
Isaku Yamahata (1):
KVM: x86/tdp_mmu: Alloc external_spt page for mirror page table
splitting
Kiryl Shutsemau (12):
x86/tdx: Move all TDX error defines into <asm/shared/tdx_errno.h>
x86/tdx: Add helpers to check return status codes
x86/virt/tdx: Allocate page bitmap for Dynamic PAMT
x86/virt/tdx: Allocate reference counters for PAMT memory
x86/virt/tdx: Improve PAMT refcounts allocation for sparse memory
x86/virt/tdx: Add tdx_alloc/free_control_page() helpers
x86/virt/tdx: Optimize tdx_alloc/free_control_page() helpers
KVM: TDX: Allocate PAMT memory for TD and vCPU control structures
KVM: TDX: Get/put PAMT pages when (un)mapping private memory
x86/virt/tdx: Enable Dynamic PAMT
Documentation/x86: Add documentation for TDX's Dynamic PAMT
x86/virt/tdx: Get/Put DPAMT page pair if and only if mapping size is
4KB
Rick Edgecombe (3):
x86/virt/tdx: Simplify tdmr_get_pamt_sz()
x86/tdx: Add APIs to support get/put of DPAMT entries from KVM, under
spinlock
KVM: x86/mmu: Prevent hugepage promotion for mirror roots in fault
path
Sean Christopherson (22):
x86/tdx: Use pg_level in TDX APIs, not the TDX-Module's 0-based level
KVM: x86/mmu: Update iter->old_spte if cmpxchg64 on mirror SPTE
"fails"
KVM: TDX: Account all non-transient page allocations for per-TD
structures
KVM: x86: Make "external SPTE" ops that can fail RET0 static calls
KVM: TDX: Drop kvm_x86_ops.link_external_spt(), use
.set_external_spte() for all
KVM: x86/mmu: Fold set_external_spte_present() into its sole caller
KVM: x86/mmu: Plumb the SPTE _pointer_ into the TDP MMU's
handle_changed_spte()
KVM: x86/mmu: Propagate mirror SPTE removal to S-EPT in
handle_changed_spte()
KVM: x86: Rework .free_external_spt() into .reclaim_external_sp()
KVM: Allow owner of kvm_mmu_memory_cache to provide a custom page
allocator
KVM: x86/mmu: Allocate/free S-EPT pages using
tdx_{alloc,free}_control_page()
*** DO NOT MERGE *** x86/virt/tdx: Don't assume guest memory is backed
by struct page
x86/virt/tdx: Extend "reset page" quirk to support huge pages
KVM: x86/mmu: Plumb the old_spte into kvm_x86_ops.set_external_spte()
KVM: TDX: Hoist tdx_sept_remove_private_spte() above
set_private_spte()
KVM: TDX: Handle removal of leaf SPTEs in .set_private_spte()
KVM: TDX: Add helper to handle mapping leaf SPTE into S-EPT
KVM: TDX: Move S-EPT page demotion TODO to tdx_sept_set_private_spte()
KVM: x86/mmu: Add Dynamic PAMT support in TDP MMU for vCPU-induced
page split
KVM: guest_memfd: Add helpers to get start/end gfns give
gmem+slot+pgoff
*** DO NOT MERGE *** KVM: guest_memfd: Add pre-zap arch hook for
shared<=>private conversion
KVM: x86/mmu: Add support for splitting S-EPT hugepages on conversion
Xiaoyao Li (1):
x86/virt/tdx: Add API to demote a 2MB mapping to 512 4KB mappings
Yan Zhao (6):
x86/virt/tdx: Enhance tdh_mem_page_aug() to support huge pages
x86/virt/tdx: Enhance tdh_phymem_page_wbinvd_hkid() to invalidate huge
pages
KVM: TDX: Add core support for splitting/demoting 2MiB S-EPT to 4KiB
KVM: x86: Introduce hugepage_set_guest_inhibit()
KVM: TDX: Honor the guest's accept level contained in an EPT violation
KVM: TDX: Turn on PG_LEVEL_2M
Documentation/arch/x86/tdx.rst | 21 +
arch/x86/coco/tdx/tdx.c | 10 +-
arch/x86/include/asm/kvm-x86-ops.h | 9 +-
arch/x86/include/asm/kvm_host.h | 36 +-
arch/x86/include/asm/shared/tdx.h | 1 +
arch/x86/include/asm/shared/tdx_errno.h | 104 +++
arch/x86/include/asm/tdx.h | 127 ++--
arch/x86/include/asm/tdx_global_metadata.h | 1 +
arch/x86/kvm/Kconfig | 1 +
arch/x86/kvm/mmu.h | 4 +
arch/x86/kvm/mmu/mmu.c | 34 +-
arch/x86/kvm/mmu/mmu_internal.h | 11 -
arch/x86/kvm/mmu/tdp_mmu.c | 315 ++++----
arch/x86/kvm/mmu/tdp_mmu.h | 2 +
arch/x86/kvm/vmx/tdx.c | 468 +++++++++---
arch/x86/kvm/vmx/tdx.h | 5 +-
arch/x86/kvm/vmx/tdx_arch.h | 3 +
arch/x86/kvm/vmx/tdx_errno.h | 40 -
arch/x86/virt/vmx/tdx/tdx.c | 762 +++++++++++++++++---
arch/x86/virt/vmx/tdx/tdx.h | 6 +-
arch/x86/virt/vmx/tdx/tdx_global_metadata.c | 7 +
include/linux/kvm_host.h | 5 +
include/linux/kvm_types.h | 2 +
virt/kvm/Kconfig | 4 +
virt/kvm/guest_memfd.c | 71 +-
virt/kvm/kvm_main.c | 7 +-
26 files changed, 1576 insertions(+), 480 deletions(-)
create mode 100644 arch/x86/include/asm/shared/tdx_errno.h
delete mode 100644 arch/x86/kvm/vmx/tdx_errno.h
base-commit: e81f7c908e1664233974b9f20beead78cde6343a
--
2.53.0.rc1.217.geba53bf80e-goog
^ permalink raw reply
* Re: [PATCH 1/2] KVM: SEV: IBPB-on-Entry guest support
From: Kim Phillips @ 2026-01-29 0:38 UTC (permalink / raw)
To: Borislav Petkov
Cc: linux-kernel, kvm, linux-coco, x86, Sean Christopherson,
Paolo Bonzini, K Prateek Nayak, Nikunj A Dadhania, Tom Lendacky,
Michael Roth, Naveen Rao, David Kaplan, stable
In-Reply-To: <20260128192312.GQaXpiIL4YFmQB2LKL@fat_crate.local>
Hi Boris,
On 1/28/26 1:23 PM, Borislav Petkov wrote:
> On Mon, Jan 26, 2026 at 04:42:04PM -0600, Kim Phillips wrote:
>> The SEV-SNP IBPB-on-Entry feature does not require a guest-side
>> implementation. The feature was added in Zen5 h/w, after the first
>> SNP Zen implementation, and thus was not accounted for when the
>> initial set of SNP features were added to the kernel.
>>
>> In its abundant precaution, commit 8c29f0165405 ("x86/sev: Add SEV-SNP
>> guest feature negotiation support") included SEV_STATUS' IBPB-on-Entry
>> bit as a reserved bit, thereby masking guests from using the feature.
>>
>> Unmask the bit, to allow guests to take advantage of the feature on
>> hypervisor kernel versions that support it: Amend the SEV_STATUS MSR
>> SNP_RESERVED_MASK to exclude bit 23 (IbpbOnEntry).
> Do not explain what the patch does.
For that last paragraph, how about:
"Allow guests to make use of IBPB-on-Entry when supported by the
hypervisor, as the bit is now architecturally defined and safe to
expose."
?
>> Fixes: 8c29f0165405 ("x86/sev: Add SEV-SNP guest feature negotiation support")
>> Cc: Nikunj A Dadhania <nikunj@amd.com>
>> Cc: Tom Lendacky <thomas.lendacky@amd.com>
>> CC: Borislav Petkov (AMD) <bp@alien8.de>
>> CC: Michael Roth <michael.roth@amd.com>
>> Cc: stable@kernel.org
> I guess...
Hopefully a bitfield will be carved out for these
no-explicit-guest-implementation-required bits by hardware such that we
won't need to do this again.
>> diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
>> index 4d3566bb1a93..9016a6b00bc7 100644
>> --- a/arch/x86/include/asm/msr-index.h
>> +++ b/arch/x86/include/asm/msr-index.h
>> @@ -735,7 +735,10 @@
>> #define MSR_AMD64_SNP_SMT_PROT BIT_ULL(MSR_AMD64_SNP_SMT_PROT_BIT)
>> #define MSR_AMD64_SNP_SECURE_AVIC_BIT 18
>> #define MSR_AMD64_SNP_SECURE_AVIC BIT_ULL(MSR_AMD64_SNP_SECURE_AVIC_BIT)
>> -#define MSR_AMD64_SNP_RESV_BIT 19
>> +#define MSR_AMD64_SNP_RESERVED_BITS19_22 GENMASK_ULL(22, 19)
>> +#define MSR_AMD64_SNP_IBPB_ON_ENTRY_BIT 23
>> +#define MSR_AMD64_SNP_IBPB_ON_ENTRY BIT_ULL(MSR_AMD64_SNP_IBPB_ON_ENTRY_BIT)
> Why isn't this part of SNP_FEATURES_PRESENT?
>
> If this feature doesn't require guest-side support, then it is trivially
> present, no?
SNP_FEATURES_PRESENT is for the non-trivial variety: Its bits get set as
part of the patchseries that add the explicit guest support *code*.
I believe 'features' like PREVENT_HOST_IBS are similar in this regard.
>> +#define MSR_AMD64_SNP_RESV_BIT 24
>> #define MSR_AMD64_SNP_RESERVED_MASK GENMASK_ULL(63, MSR_AMD64_SNP_RESV_BIT)
>> #define MSR_AMD64_SAVIC_CONTROL 0xc0010138
>> #define MSR_AMD64_SAVIC_EN_BIT 0
>> --
> I guess this is a fix of sorts and I could take it in now once all review
> comments have been addressed...
Cool, thanks.
Kim
^ permalink raw reply
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