[PATCH 2/2] x86/virt/tdx: Use PFN directly for unmapping guest private memory

Yan Zhao
2026-03-19T01:37:34Z

From: Sean Christopherson <seanjc@google.com>

Remove the completely unnecessary assumptions that memory unmapped from a
TDX guest is backed by refcounted struct page memory.

APIs tdh_phymem_page_wbinvd_hkid(), tdx_quirk_reset_page() are used when
unmapping guest private memory from S-EPT. Since mapping of guest private
memory places no requirements on how KVM and guest_memfd manage memory,
neither does guest private memory unmapping.

Rip out the misguided struct page assumptions/constraints by having the two
APIs take PFN directly. This ensures that for future huge page support in
S-EPT, the kernel doesn't pick up even worse assumptions like "a hugepage
must be contained in a single folio".

Use "kvm_pfn_t pfn" for type safety. Using this KVM type is appropriate
since APIs tdh_phymem_page_wbinvd_hkid() and tdx_quirk_reset_page() are
exported to KVM only.

Update mk_keyed_paddr(), which is invoked by tdh_phymem_page_wbinvd_hkid(),
to take PFN as parameter accordingly. Opportunistically, move
mk_keyed_paddr() from tdx.h to tdx.c since there are no external users.

Have tdx_reclaim_page() remain using struct page as parameter since it's
currently not used for removing guest private memory yet.

[Yan: Use kvm_pfn_t, drop reclaim API param update, move mk_keyed_paddr()]

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
---
arch/x86/include/asm/tdx.h | 15 ++-------------
arch/x86/kvm/vmx/tdx.c | 10 +++++-----
arch/x86/virt/vmx/tdx/tdx.c | 16 +++++++++++-----
3 files changed, 18 insertions(+), 23 deletions(-)

diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index f3f0b1872176..6ceb4cd9ff21 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -153,7 +153,7 @@ 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);
+void tdx_quirk_reset_page(kvm_pfn_t pfn);

struct tdx_td {
/* TD root structure: */
@@ -177,17 +177,6 @@ struct tdx_vp {
struct page **tdcx_pages;
};

-static inline u64 mk_keyed_paddr(u16 hkid, struct page *page)
-{
- u64 ret;
-
- ret = page_to_phys(page);
- /* KeyID bits are just above the physical address bits: */
- ret |= (u64)hkid << boot_cpu_data.x86_phys_bits;
-
- return ret;
-}
-
static inline int pg_level_to_tdx_sept_level(enum pg_level level)
{
WARN_ON_ONCE(level == PG_LEVEL_NONE);
@@ -219,7 +208,7 @@ 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_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);
+u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, kvm_pfn_t pfn);
#else
static inline void tdx_init(void) { }
static inline u32 tdx_get_nr_guest_keyids(void) { return 0; }
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 1f1abc5b5655..75ad3debcd84 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -343,7 +343,7 @@ static int tdx_reclaim_page(struct page *page)

r = __tdx_reclaim_page(page);
if (!r)
- tdx_quirk_reset_page(page);
+ tdx_quirk_reset_page(page_to_pfn(page));
return r;
}

@@ -597,7 +597,7 @@ static void tdx_reclaim_td_control_pages(struct kvm *kvm)
if (TDX_BUG_ON(err, TDH_PHYMEM_PAGE_WBINVD, kvm))
return;

- tdx_quirk_reset_page(kvm_tdx->td.tdr_page);
+ tdx_quirk_reset_page(page_to_pfn(kvm_tdx->td.tdr_page));

__free_page(kvm_tdx->td.tdr_page);
kvm_tdx->td.tdr_page = NULL;
@@ -1776,9 +1776,9 @@ static int tdx_sept_free_private_spt(struct kvm *kvm, gfn_t gfn,
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);
+ kvm_pfn_t pfn = spte_to_pfn(mirror_spte);
gpa_t gpa = gfn_to_gpa(gfn);
u64 err, entry, level_state;

@@ -1817,11 +1817,11 @@ static void tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn,
if (TDX_BUG_ON_2(err, TDH_MEM_PAGE_REMOVE, entry, level_state, kvm))
return;

- err = tdh_phymem_page_wbinvd_hkid((u16)kvm_tdx->hkid, page);
+ err = tdh_phymem_page_wbinvd_hkid((u16)kvm_tdx->hkid, pfn);
if (TDX_BUG_ON(err, TDH_PHYMEM_PAGE_WBINVD, kvm))
return;

- tdx_quirk_reset_page(page);
+ tdx_quirk_reset_page(pfn);
}

void tdx_deliver_interrupt(struct kvm_lapic *apic, int delivery_mode,
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index a9dd75190c67..2f9d07ad1a9a 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -730,9 +730,9 @@ static void tdx_quirk_reset_paddr(unsigned long base, unsigned long size)
mb();
}

-void tdx_quirk_reset_page(struct page *page)
+void tdx_quirk_reset_page(kvm_pfn_t pfn)
{
- tdx_quirk_reset_paddr(page_to_phys(page), PAGE_SIZE);
+ tdx_quirk_reset_paddr(PFN_PHYS(pfn), PAGE_SIZE);
}
EXPORT_SYMBOL_FOR_KVM(tdx_quirk_reset_page);

@@ -1907,21 +1907,27 @@ u64 tdh_phymem_cache_wb(bool resume)
}
EXPORT_SYMBOL_FOR_KVM(tdh_phymem_cache_wb);

+static inline u64 mk_keyed_paddr(u16 hkid, kvm_pfn_t pfn)
+{
+ /* KeyID bits are just above the physical address bits. */
+ return PFN_PHYS(pfn) | ((u64)hkid << boot_cpu_data.x86_phys_bits);
+}
+
u64 tdh_phymem_page_wbinvd_tdr(struct tdx_td *td)
{
struct tdx_module_args args = {};

- args.rcx = mk_keyed_paddr(tdx_global_keyid, td->tdr_page);
+ args.rcx = mk_keyed_paddr(tdx_global_keyid, page_to_pfn(td->tdr_page));

return seamcall(TDH_PHYMEM_PAGE_WBINVD, &args);
}
EXPORT_SYMBOL_FOR_KVM(tdh_phymem_page_wbinvd_tdr);

-u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page)
+u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, kvm_pfn_t pfn)
{
struct tdx_module_args args = {};

- args.rcx = mk_keyed_paddr(hkid, page);
+ args.rcx = mk_keyed_paddr(hkid, pfn);

return seamcall(TDH_PHYMEM_PAGE_WBINVD, &args);
}
--
2.43.2