[PATCH RESEND v4 5/9] KVM: VMX: Add init/set/get functions for SPP

Yang Weijiang
2019-08-14T07:02:38Z

init_spp() must be called before {get, set}_subpage
functions, it creates subpage access bitmaps for memory pages
and issues a KVM request to setup SPPT root pages.

kvm_mmu_set_subpages() is to enable SPP bit in EPT leaf page
and setup corresponding SPPT entries. The mmu_lock
is held before above operation. If it's called in EPT fault and
SPPT mis-config induced handler, mmu_lock is acquired outside
the function, otherwise, it's acquired inside it.

kvm_mmu_get_subpages() is used to query access bitmap for
protected page, it's also used in EPT fault handler to check
whether the fault EPT page is SPP protected as well.

Co-developed-by: He Chen <he.chen@linux.intel.com>
Signed-off-by: He Chen <he.chen@linux.intel.com>
Co-developed-by: Zhang Yi <yi.z.zhang@linux.intel.com>
Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
---
arch/x86/include/asm/kvm_host.h | 18 ++++
arch/x86/include/asm/vmx.h | 2 +
arch/x86/kvm/mmu.c | 160 ++++++++++++++++++++++++++++++++
arch/x86/kvm/vmx/vmx.c | 48 ++++++++++
arch/x86/kvm/x86.c | 40 ++++++++
include/linux/kvm_host.h | 4 +-
include/uapi/linux/kvm.h | 9 ++
7 files changed, 280 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 44f6e1757861..5c4882015acc 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -398,8 +398,13 @@ struct kvm_mmu {
void (*invlpg)(struct kvm_vcpu *vcpu, gva_t gva, hpa_t root_hpa);
void (*update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
u64 *spte, const void *pte);
+ int (*get_subpages)(struct kvm *kvm, struct kvm_subpage *spp_info);
+ int (*set_subpages)(struct kvm *kvm, struct kvm_subpage *spp_info);
+ int (*init_spp)(struct kvm *kvm);
+
hpa_t root_hpa;
gpa_t root_cr3;
+ hpa_t sppt_root;
union kvm_mmu_role mmu_role;
u8 root_level;
u8 shadow_root_level;
@@ -927,6 +932,8 @@ struct kvm_arch {

bool guest_can_read_msr_platform_info;
bool exception_payload_enabled;
+
+ bool spp_active;
};

struct kvm_vm_stat {
@@ -1199,6 +1206,11 @@ struct kvm_x86_ops {
uint16_t (*nested_get_evmcs_version)(struct kvm_vcpu *vcpu);

bool (*need_emulation_on_page_fault)(struct kvm_vcpu *vcpu);
+
+ bool (*get_spp_status)(void);
+ int (*get_subpages)(struct kvm *kvm, struct kvm_subpage *spp_info);
+ int (*set_subpages)(struct kvm *kvm, struct kvm_subpage *spp_info);
+ int (*init_spp)(struct kvm *kvm);
};

struct kvm_arch_async_pf {
@@ -1417,6 +1429,12 @@ void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva);
void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid);
void kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3, bool skip_tlb_flush);

+int kvm_mmu_get_subpages(struct kvm *kvm, struct kvm_subpage *spp_info,
+ bool mmu_locked);
+int kvm_mmu_set_subpages(struct kvm *kvm, struct kvm_subpage *spp_info,
+ bool mmu_locked);
+int kvm_mmu_init_spp(struct kvm *kvm);
+
void kvm_enable_tdp(void);
void kvm_disable_tdp(void);

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index a2c9e18e0ad7..6cb05ac07453 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -224,6 +224,8 @@ enum vmcs_field {
XSS_EXIT_BITMAP_HIGH = 0x0000202D,
ENCLS_EXITING_BITMAP = 0x0000202E,
ENCLS_EXITING_BITMAP_HIGH = 0x0000202F,
+ SPPT_POINTER = 0x00002030,
+ SPPT_POINTER_HIGH = 0x00002031,
TSC_MULTIPLIER = 0x00002032,
TSC_MULTIPLIER_HIGH = 0x00002033,
GUEST_PHYSICAL_ADDRESS = 0x00002400,
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 16e390fd6e58..16d3ca544b67 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3756,6 +3756,9 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
(mmu->root_level >= PT64_ROOT_4LEVEL || mmu->direct_map)) {
mmu_free_root_page(vcpu->kvm, &mmu->root_hpa,
&invalid_list);
+ if (vcpu->kvm->arch.spp_active)
+ mmu_free_root_page(vcpu->kvm, &mmu->sppt_root,
+ &invalid_list);
} else {
for (i = 0; i < 4; ++i)
if (mmu->pae_root[i] != 0)
@@ -4414,6 +4417,158 @@ int kvm_mmu_setup_spp_structure(struct kvm_vcpu *vcpu,
return ret;
}
EXPORT_SYMBOL_GPL(kvm_mmu_setup_spp_structure);
+
+int kvm_mmu_init_spp(struct kvm *kvm)
+{
+ int i, ret;
+ struct kvm_vcpu *vcpu;
+ int root_level;
+ struct kvm_mmu_page *ssp_sp;
+
+
+ if (!kvm_x86_ops->get_spp_status())
+ return -ENODEV;
+
+ if (kvm->arch.spp_active)
+ return 0;
+
+ ret = kvm_subpage_create_bitmaps(kvm);
+
+ if (ret)
+ return ret;
+
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ /* prepare caches for SPP setup.*/
+ mmu_topup_memory_caches(vcpu);
+ root_level = vcpu->arch.mmu->shadow_root_level;
+ ssp_sp = kvm_mmu_get_spp_page(vcpu, 0, root_level);
+ ++ssp_sp->root_count;
+ vcpu->arch.mmu->sppt_root = __pa(ssp_sp->spt);
+ kvm_make_request(KVM_REQ_LOAD_CR3, vcpu);
+ }
+
+ kvm->arch.spp_active = true;
+ return 0;
+}
+
+int kvm_mmu_get_subpages(struct kvm *kvm, struct kvm_subpage *spp_info,
+ bool mmu_locked)
+{
+ u32 *access = spp_info->access_map;
+ gfn_t gfn = spp_info->base_gfn;
+ int npages = spp_info->npages;
+ struct kvm_memory_slot *slot;
+ int i;
+ int ret;
+
+ if (!kvm->arch.spp_active)
+ return -ENODEV;
+
+ if (!mmu_locked)
+ spin_lock(&kvm->mmu_lock);
+
+ for (i = 0; i < npages; i++, gfn++) {
+ slot = gfn_to_memslot(kvm, gfn);
+ if (!slot) {
+ ret = -EFAULT;
+ goto out_unlock;
+ }
+ access[i] = *gfn_to_subpage_wp_info(slot, gfn);
+ }
+
+ ret = i;
+
+out_unlock:
+ if (!mmu_locked)
+ spin_unlock(&kvm->mmu_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kvm_mmu_get_subpages);
+
+int kvm_mmu_set_subpages(struct kvm *kvm, struct kvm_subpage *spp_info,
+ bool mmu_locked)
+{
+ u32 *access = spp_info->access_map;
+ gfn_t gfn = spp_info->base_gfn;
+ int npages = spp_info->npages;
+ struct kvm_memory_slot *slot;
+ struct kvm_vcpu *vcpu;
+ struct kvm_rmap_head *rmap_head;
+ int i, k;
+ u32 *wp_map;
+ int ret = -EFAULT;
+
+ if (!kvm->arch.spp_active)
+ return -ENODEV;
+
+ if (!mmu_locked)
+ spin_lock(&kvm->mmu_lock);
+
+ for (i = 0; i < npages; i++, gfn++) {
+ slot = gfn_to_memslot(kvm, gfn);
+ if (!slot)
+ goto out_unlock;
+
+ /*
+ * check whether the target 4KB page exists in EPT leaf
+ * entries.If it's there, we can setup SPP protection now,
+ * otherwise, need to defer it to EPT page fault handler.
+ */
+ rmap_head = __gfn_to_rmap(gfn, PT_PAGE_TABLE_LEVEL, slot);
+
+ if (rmap_head->val) {
+ /*
+ * if all subpages are not writable, open SPP bit in
+ * EPT leaf entry to enable SPP protection for
+ * corresponding page.
+ */
+ if (access[i] != FULL_SPP_ACCESS) {
+ ret = kvm_mmu_open_subpage_write_protect(kvm,
+ slot, gfn);
+
+ if (ret)
+ goto out_err;
+
+ kvm_for_each_vcpu(k, vcpu, kvm)
+ kvm_mmu_setup_spp_structure(vcpu,
+ access[i], gfn);
+ } else {
+ ret = kvm_mmu_clear_subpage_write_protect(kvm,
+ slot, gfn);
+ if (ret)
+ goto out_err;
+ }
+
+ } else
+ pr_info("%s - No ETP entry, gfn = 0x%llx, access = 0x%x.\n", __func__, gfn, access[i]);
+
+ /* if this function is called in tdp_page_fault() or
+ * spp_handler(), mmu_locked = true, SPP access bitmap
+ * is being used, otherwise, it's being stored.
+ */
+ if (!mmu_locked) {
+ wp_map = gfn_to_subpage_wp_info(slot, gfn);
+ *wp_map = access[i];
+ }
+ }
+
+ ret = i;
+out_err:
+ if (ret < 0)
+ pr_info("SPP-Error, didn't get the gfn:" \
+ "%llx from EPT leaf.\n"
+ "Current we don't support SPP on" \
+ "huge page.\n"
+ "Please disable huge page and have" \
+ "another try.\n", gfn);
+out_unlock:
+ if (!mmu_locked)
+ spin_unlock(&kvm->mmu_lock);
+
+ return ret;
+}
+
static void nonpaging_init_context(struct kvm_vcpu *vcpu,
struct kvm_mmu *context)
{
@@ -5104,6 +5259,9 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
context->get_cr3 = get_cr3;
context->get_pdptr = kvm_pdptr_read;
context->inject_page_fault = kvm_inject_page_fault;
+ context->get_subpages = kvm_x86_ops->get_subpages;
+ context->set_subpages = kvm_x86_ops->set_subpages;
+ context->init_spp = kvm_x86_ops->init_spp;

if (!is_paging(vcpu)) {
context->nx = false;
@@ -5309,6 +5467,8 @@ void kvm_init_mmu(struct kvm_vcpu *vcpu, bool reset_roots)
uint i;

vcpu->arch.mmu->root_hpa = INVALID_PAGE;
+ if (!vcpu->kvm->arch.spp_active)
+ vcpu->arch.mmu->sppt_root = INVALID_PAGE;

for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
vcpu->arch.mmu->prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a0753a36155d..855d02dd94c7 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2847,11 +2847,17 @@ u64 construct_eptp(struct kvm_vcpu *vcpu, unsigned long root_hpa)
return eptp;
}

+static inline u64 construct_spptp(unsigned long root_hpa)
+{
+ return root_hpa & PAGE_MASK;
+}
+
void vmx_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
{
struct kvm *kvm = vcpu->kvm;
unsigned long guest_cr3;
u64 eptp;
+ u64 spptp;

guest_cr3 = cr3;
if (enable_ept) {
@@ -2874,6 +2880,12 @@ void vmx_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
ept_load_pdptrs(vcpu);
}

+ if (kvm->arch.spp_active && VALID_PAGE(vcpu->arch.mmu->sppt_root)) {
+ spptp = construct_spptp(vcpu->arch.mmu->sppt_root);
+ vmcs_write64(SPPT_POINTER, spptp);
+ vmx_flush_tlb(vcpu, true);
+ }
+
vmcs_writel(GUEST_CR3, guest_cr3);
}

@@ -5735,6 +5747,9 @@ void dump_vmcs(void)
pr_err("PostedIntrVec = 0x%02x\n", vmcs_read16(POSTED_INTR_NV));
if ((secondary_exec_control & SECONDARY_EXEC_ENABLE_EPT))
pr_err("EPT pointer = 0x%016llx\n", vmcs_read64(EPT_POINTER));
+ if ((secondary_exec_control & SECONDARY_EXEC_ENABLE_SPP))
+ pr_err("SPPT pointer = 0x%016llx\n", vmcs_read64(SPPT_POINTER));
+
n = vmcs_read32(CR3_TARGET_COUNT);
for (i = 0; i + 1 < n; i += 4)
pr_err("CR3 target%u=%016lx target%u=%016lx\n",
@@ -7546,6 +7561,12 @@ static __init int hardware_setup(void)
kvm_x86_ops->enable_log_dirty_pt_masked = NULL;
}

+ if (!spp_supported) {
+ kvm_x86_ops->get_subpages = NULL;
+ kvm_x86_ops->set_subpages = NULL;
+ kvm_x86_ops->init_spp = NULL;
+ }
+
if (!cpu_has_vmx_preemption_timer())
kvm_x86_ops->request_immediate_exit = __kvm_request_immediate_exit;

@@ -7592,6 +7613,28 @@ static __exit void hardware_unsetup(void)
free_kvm_area();
}

+static bool vmx_get_spp_status(void)
+{
+ return spp_supported;
+}
+
+static int vmx_get_subpages(struct kvm *kvm,
+ struct kvm_subpage *spp_info)
+{
+ return kvm_get_subpages(kvm, spp_info);
+}
+
+static int vmx_set_subpages(struct kvm *kvm,
+ struct kvm_subpage *spp_info)
+{
+ return kvm_set_subpages(kvm, spp_info);
+}
+
+static int vmx_init_spp(struct kvm *kvm)
+{
+ return kvm_init_spp(kvm);
+}
+
static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
.cpu_has_kvm_support = cpu_has_kvm_support,
.disabled_by_bios = vmx_disabled_by_bios,
@@ -7740,6 +7783,11 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
.get_vmcs12_pages = NULL,
.nested_enable_evmcs = NULL,
.need_emulation_on_page_fault = vmx_need_emulation_on_page_fault,
+
+ .get_spp_status = vmx_get_spp_status,
+ .get_subpages = vmx_get_subpages,
+ .set_subpages = vmx_set_subpages,
+ .init_spp = vmx_init_spp,
};

static void vmx_cleanup_l1d_flush(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 26e4c574731c..c7cb17941344 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4589,6 +4589,44 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
return r;
}

+int kvm_get_subpages(struct kvm *kvm,
+ struct kvm_subpage *spp_info)
+{
+ int ret;
+
+ mutex_lock(&kvm->slots_lock);
+ ret = kvm_mmu_get_subpages(kvm, spp_info, false);
+ mutex_unlock(&kvm->slots_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kvm_get_subpages);
+
+int kvm_set_subpages(struct kvm *kvm,
+ struct kvm_subpage *spp_info)
+{
+ int ret;
+
+ mutex_lock(&kvm->slots_lock);
+ ret = kvm_mmu_set_subpages(kvm, spp_info, false);
+ mutex_unlock(&kvm->slots_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kvm_set_subpages);
+
+int kvm_init_spp(struct kvm *kvm)
+{
+ int ret;
+
+ mutex_lock(&kvm->slots_lock);
+ ret = kvm_mmu_init_spp(kvm);
+ mutex_unlock(&kvm->slots_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kvm_init_spp);
+
long kvm_arch_vm_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
@@ -9349,6 +9387,8 @@ void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
}

kvm_page_track_free_memslot(free, dont);
+ if (kvm->arch.spp_active)
+ kvm_subpage_free_memslot(free, dont);
}

int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 7f904d4d788c..da30fcbb2727 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -849,7 +849,9 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu);

struct kvm_mmu_page *kvm_mmu_get_spp_page(struct kvm_vcpu *vcpu,
gfn_t gfn, unsigned int level);
-
+int kvm_get_subpages(struct kvm *kvm, struct kvm_subpage *spp_info);
+int kvm_set_subpages(struct kvm *kvm, struct kvm_subpage *spp_info);
+int kvm_init_spp(struct kvm *kvm);
#ifndef __KVM_HAVE_ARCH_VM_ALLOC
/*
* All architectures that want to use vzalloc currently also
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 6d4ea4b6c922..2c75a87ab3b5 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -102,6 +102,15 @@ struct kvm_userspace_memory_region {
__u64 userspace_addr; /* start of the userspace allocated memory */
};

+/* for KVM_SUBPAGES_GET_ACCESS and KVM_SUBPAGES_SET_ACCESS */
+#define SUBPAGE_MAX_BITMAP 64
+struct kvm_subpage {
+ __u64 base_gfn;
+ __u64 npages;
+ /* sub-page write-access bitmap array */
+ __u32 access_map[SUBPAGE_MAX_BITMAP];
+};
+
/*
* The bit 0 ~ bit 15 of kvm_memory_region::flags are visible for userspace,
* other bits are reserved for kvm internal use which are defined in
--
2.17.2