[PATCH v3 4/5] KVM: MMU: Add 5 level EPT & Shadow page table support.

From: Yu Zhang
Date: Thu Aug 24 2017 - 08:51:18 EST

Extends the shadow paging code, so that 5 level shadow page
table can be constructed if VM is running in 5 level paging
mode.

Also extends the ept code, so that 5 level ept table can be
constructed if maxphysaddr of VM exceeds 48 bits. Unlike the
shadow logic, KVM should still use 4 level ept table for a VM
whose physical address width is less than 48 bits, even when
the VM is running in 5 level paging mode.

Signed-off-by: Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 10 +++++-----
arch/x86/include/asm/vmx.h | 2 ++
arch/x86/kvm/cpuid.c | 5 +++++
arch/x86/kvm/mmu.c | 43 +++++++++++++++++++++++++++--------------
arch/x86/kvm/mmu.h | 1 +
arch/x86/kvm/mmu_audit.c | 4 ++--
arch/x86/kvm/svm.c | 4 ++--
arch/x86/kvm/vmx.c | 21 ++++++++++++++------
arch/x86/kvm/x86.h | 10 ++++++++++
9 files changed, 71 insertions(+), 29 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 5907d46..bdef532 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -315,7 +315,7 @@ struct kvm_pio_request {
int size;
};

-#define PT64_ROOT_MAX_LEVEL 4
+#define PT64_ROOT_MAX_LEVEL 5

struct rsvd_bits_validate {
u64 rsvd_bits_mask[2][PT64_ROOT_MAX_LEVEL];
@@ -323,9 +323,9 @@ struct rsvd_bits_validate {
};

/*
- * x86 supports 3 paging modes (4-level 64-bit, 3-level 64-bit, and 2-level
- * 32-bit). The kvm_mmu structure abstracts the details of the current mmu
- * mode.
+ * x86 supports 4 paging modes (5-level 64-bit, 4-level 64-bit, 3-level 32-bit,
+ * and 2-level 32-bit). The kvm_mmu structure abstracts the details of the
+ * current mmu mode.
*/
struct kvm_mmu {
void (*set_cr3)(struct kvm_vcpu *vcpu, unsigned long root);
@@ -982,7 +982,7 @@ struct kvm_x86_ops {
void (*deliver_posted_interrupt)(struct kvm_vcpu *vcpu, int vector);
int (*sync_pir_to_irr)(struct kvm_vcpu *vcpu);
int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
- int (*get_tdp_level)(void);
+ int (*get_tdp_level)(struct kvm_vcpu *vcpu);
u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
int (*get_lpage_level)(void);
bool (*rdtscp_supported)(void);
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 340007a..caec841 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -453,6 +453,7 @@ enum vmcs_field {

#define VMX_EPT_EXECUTE_ONLY_BIT (1ull)
#define VMX_EPT_PAGE_WALK_4_BIT (1ull << 6)
+#define VMX_EPT_PAGE_WALK_5_BIT (1ull << 7)
#define VMX_EPTP_UC_BIT (1ull << 8)
#define VMX_EPTP_WB_BIT (1ull << 14)
#define VMX_EPT_2MB_PAGE_BIT (1ull << 16)
@@ -471,6 +472,7 @@ enum vmcs_field {
#define VMX_EPT_MT_EPTE_SHIFT 3
#define VMX_EPTP_PWL_MASK 0x38ull
#define VMX_EPTP_PWL_4 0x18ull
+#define VMX_EPTP_PWL_5 0x20ull
#define VMX_EPTP_AD_ENABLE_BIT (1ull << 6)
#define VMX_EPTP_MT_MASK 0x7ull
#define VMX_EPTP_MT_WB 0x6ull
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 1450547..83865a3 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -137,6 +137,11 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
/* Update physical-address width */
vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu);

+#ifdef CONFIG_X86_64
+ if (vcpu->arch.maxphyaddr > 48)
+ kvm_mmu_reset_context(vcpu);
+#endif
+
kvm_pmu_refresh(vcpu);
return 0;
}
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 3faa20c..f47ccca 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3322,8 +3322,8 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
return;

- if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_4LEVEL &&
- (vcpu->arch.mmu.root_level == PT64_ROOT_4LEVEL ||
+ if (vcpu->arch.mmu.shadow_root_level >= PT64_ROOT_4LEVEL &&
+ (vcpu->arch.mmu.root_level >= PT64_ROOT_4LEVEL ||
vcpu->arch.mmu.direct_map)) {
hpa_t root = vcpu->arch.mmu.root_hpa;

@@ -3375,13 +3375,14 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
struct kvm_mmu_page *sp;
unsigned i;

- if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_4LEVEL) {
+ if (vcpu->arch.mmu.shadow_root_level >= PT64_ROOT_4LEVEL) {
spin_lock(&vcpu->kvm->mmu_lock);
if(make_mmu_pages_available(vcpu) < 0) {
spin_unlock(&vcpu->kvm->mmu_lock);
return 1;
}
- sp = kvm_mmu_get_page(vcpu, 0, 0, PT64_ROOT_4LEVEL, 1, ACC_ALL);
+ sp = kvm_mmu_get_page(vcpu, 0, 0,
+ vcpu->arch.mmu.shadow_root_level, 1, ACC_ALL);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
vcpu->arch.mmu.root_hpa = __pa(sp->spt);
@@ -3425,7 +3426,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
* Do we shadow a long mode page table? If so we need to
* write-protect the guests page table root.
*/
- if (vcpu->arch.mmu.root_level == PT64_ROOT_4LEVEL) {
+ if (vcpu->arch.mmu.root_level >= PT64_ROOT_4LEVEL) {
hpa_t root = vcpu->arch.mmu.root_hpa;

MMU_WARN_ON(VALID_PAGE(root));
@@ -3435,8 +3436,8 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
spin_unlock(&vcpu->kvm->mmu_lock);
return 1;
}
- sp = kvm_mmu_get_page(vcpu, root_gfn, 0, PT64_ROOT_4LEVEL,
- 0, ACC_ALL);
+ sp = kvm_mmu_get_page(vcpu, root_gfn, 0,
+ vcpu->arch.mmu.shadow_root_level, 0, ACC_ALL);
root = __pa(sp->spt);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
@@ -3531,7 +3532,7 @@ static void mmu_sync_roots(struct kvm_vcpu *vcpu)

vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY);
kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC);
- if (vcpu->arch.mmu.root_level == PT64_ROOT_4LEVEL) {
+ if (vcpu->arch.mmu.root_level >= PT64_ROOT_4LEVEL) {
hpa_t root = vcpu->arch.mmu.root_hpa;
sp = page_header(root);
mmu_sync_children(vcpu, sp);
@@ -4057,6 +4058,12 @@ __reset_rsvds_bits_mask(struct kvm_vcpu *vcpu,
rsvd_check->rsvd_bits_mask[1][0] =
rsvd_check->rsvd_bits_mask[0][0];
break;
+ case PT64_ROOT_5LEVEL:
+ rsvd_check->rsvd_bits_mask[0][4] = exb_bit_rsvd |
+ nonleaf_bit8_rsvd | rsvd_bits(7, 7) |
+ rsvd_bits(maxphyaddr, 51);
+ rsvd_check->rsvd_bits_mask[1][4] =
+ rsvd_check->rsvd_bits_mask[0][4];
case PT64_ROOT_4LEVEL:
rsvd_check->rsvd_bits_mask[0][3] = exb_bit_rsvd |
nonleaf_bit8_rsvd | rsvd_bits(7, 7) |
@@ -4098,6 +4105,8 @@ __reset_rsvds_bits_mask_ept(struct rsvd_bits_validate *rsvd_check,
{
u64 bad_mt_xwr;

+ rsvd_check->rsvd_bits_mask[0][4] =
+ rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 7);
rsvd_check->rsvd_bits_mask[0][3] =
rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 7);
rsvd_check->rsvd_bits_mask[0][2] =
@@ -4107,6 +4116,7 @@ __reset_rsvds_bits_mask_ept(struct rsvd_bits_validate *rsvd_check,
rsvd_check->rsvd_bits_mask[0][0] = rsvd_bits(maxphyaddr, 51);

/* large page */
+ rsvd_check->rsvd_bits_mask[1][4] = rsvd_check->rsvd_bits_mask[0][4];
rsvd_check->rsvd_bits_mask[1][3] = rsvd_check->rsvd_bits_mask[0][3];
rsvd_check->rsvd_bits_mask[1][2] =
rsvd_bits(maxphyaddr, 51) | rsvd_bits(12, 29);
@@ -4367,7 +4377,10 @@ static void paging64_init_context_common(struct kvm_vcpu *vcpu,
static void paging64_init_context(struct kvm_vcpu *vcpu,
struct kvm_mmu *context)
{
- paging64_init_context_common(vcpu, context, PT64_ROOT_4LEVEL);
+ int root_level = is_la57_mode(vcpu) ?
+ PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL;
+
+ paging64_init_context_common(vcpu, context, root_level);
}

static void paging32_init_context(struct kvm_vcpu *vcpu,
@@ -4408,7 +4421,7 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
context->sync_page = nonpaging_sync_page;
context->invlpg = nonpaging_invlpg;
context->update_pte = nonpaging_update_pte;
- context->shadow_root_level = kvm_x86_ops->get_tdp_level();
+ context->shadow_root_level = kvm_x86_ops->get_tdp_level(vcpu);
context->root_hpa = INVALID_PAGE;
context->direct_map = true;
context->set_cr3 = kvm_x86_ops->set_tdp_cr3;
@@ -4422,7 +4435,8 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
context->root_level = 0;
} else if (is_long_mode(vcpu)) {
context->nx = is_nx(vcpu);
- context->root_level = PT64_ROOT_4LEVEL;
+ context->root_level = is_la57_mode(vcpu) ?
+ PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL;
reset_rsvds_bits_mask(vcpu, context);
context->gva_to_gpa = paging64_gva_to_gpa;
} else if (is_pae(vcpu)) {
@@ -4479,7 +4493,7 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,

MMU_WARN_ON(VALID_PAGE(context->root_hpa));

- context->shadow_root_level = kvm_x86_ops->get_tdp_level();
+ context->shadow_root_level = PT64_ROOT_4LEVEL;

context->nx = true;
context->ept_ad = accessed_dirty;
@@ -4488,7 +4502,7 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
context->sync_page = ept_sync_page;
context->invlpg = ept_invlpg;
context->update_pte = ept_update_pte;
- context->root_level = context->shadow_root_level;
+ context->root_level = PT64_ROOT_4LEVEL;
context->root_hpa = INVALID_PAGE;
context->direct_map = false;
context->base_role.ad_disabled = !accessed_dirty;
@@ -4533,7 +4547,8 @@ static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu)
g_context->gva_to_gpa = nonpaging_gva_to_gpa_nested;
} else if (is_long_mode(vcpu)) {
g_context->nx = is_nx(vcpu);
- g_context->root_level = PT64_ROOT_4LEVEL;
+ g_context->root_level = is_la57_mode(vcpu) ?
+ PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL;
reset_rsvds_bits_mask(vcpu, g_context);
g_context->gva_to_gpa = paging64_gva_to_gpa_nested;
} else if (is_pae(vcpu)) {
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 45b9a11..e2999f5 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -37,6 +37,7 @@
#define PT32_DIR_PSE36_MASK \
(((1ULL << PT32_DIR_PSE36_SIZE) - 1) << PT32_DIR_PSE36_SHIFT)

+#define PT64_ROOT_5LEVEL 5
#define PT64_ROOT_4LEVEL 4
#define PT32_ROOT_LEVEL 2
#define PT32E_ROOT_LEVEL 3
diff --git a/arch/x86/kvm/mmu_audit.c b/arch/x86/kvm/mmu_audit.c
index 2e6996d..d22ddbd 100644
--- a/arch/x86/kvm/mmu_audit.c
+++ b/arch/x86/kvm/mmu_audit.c
@@ -62,11 +62,11 @@ static void mmu_spte_walk(struct kvm_vcpu *vcpu, inspect_spte_fn fn)
if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
return;

- if (vcpu->arch.mmu.root_level == PT64_ROOT_4LEVEL) {
+ if (vcpu->arch.mmu.root_level >= PT64_ROOT_4LEVEL) {
hpa_t root = vcpu->arch.mmu.root_hpa;

sp = page_header(root);
- __mmu_spte_walk(vcpu, sp, fn, PT64_ROOT_4LEVEL);
+ __mmu_spte_walk(vcpu, sp, fn, vcpu->arch.mmu.root_level);
return;
}

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 19e43ca..7161d79 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -563,7 +563,7 @@ static inline void invlpga(unsigned long addr, u32 asid)
asm volatile (__ex(SVM_INVLPGA) : : "a"(addr), "c"(asid));
}

-static int get_npt_level(void)
+static int get_npt_level(struct kvm_vcpu *vcpu)
{
#ifdef CONFIG_X86_64
return PT64_ROOT_4LEVEL;
@@ -2370,7 +2370,7 @@ static void nested_svm_init_mmu_context(struct kvm_vcpu *vcpu)
vcpu->arch.mmu.get_cr3 = nested_svm_get_tdp_cr3;
vcpu->arch.mmu.get_pdptr = nested_svm_get_tdp_pdptr;
vcpu->arch.mmu.inject_page_fault = nested_svm_inject_npf_exit;
- vcpu->arch.mmu.shadow_root_level = get_npt_level();
+ vcpu->arch.mmu.shadow_root_level = get_npt_level(vcpu);
reset_shadow_zero_bits_mask(vcpu, &vcpu->arch.mmu);
vcpu->arch.walk_mmu = &vcpu->arch.nested_mmu;
}
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 19aa69a..d4038a1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1205,6 +1205,11 @@ static inline bool cpu_has_vmx_ept_mt_wb(void)
return vmx_capability.ept & VMX_EPTP_WB_BIT;
}

+static inline bool cpu_has_vmx_ept_5levels(void)
+{
+ return vmx_capability.ept & VMX_EPT_PAGE_WALK_5_BIT;
+}
+
static inline bool cpu_has_vmx_ept_ad_bits(void)
{
return vmx_capability.ept & VMX_EPT_AD_BIT;
@@ -4301,9 +4306,18 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
vmx->emulation_required = emulation_required(vcpu);
}

+static int get_ept_level(struct kvm_vcpu *vcpu)
+{
+ if (cpu_has_vmx_ept_5levels() && (cpuid_maxphyaddr(vcpu) > 48))
+ return 5;
+ return 4;
+}
+
static u64 construct_eptp(struct kvm_vcpu *vcpu, unsigned long root_hpa)
{
- u64 eptp = VMX_EPTP_MT_WB | VMX_EPTP_PWL_4;
+ u64 eptp = VMX_EPTP_MT_WB;
+
+ eptp |= (get_ept_level(vcpu) == 5) ? VMX_EPTP_PWL_5 : VMX_EPTP_PWL_4;

if (enable_ept_ad_bits &&
(!is_guest_mode(vcpu) || nested_ept_ad_enabled(vcpu)))
@@ -9501,11 +9515,6 @@ static void __init vmx_check_processor_compat(void *rtn)
}
}

-static int get_ept_level(void)
-{
- return 4;
-}
-
static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
{
u8 cache;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 1134603..69de8bf 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -62,6 +62,16 @@ static inline bool is_64_bit_mode(struct kvm_vcpu *vcpu)
return cs_l;
}

+static inline bool is_la57_mode(struct kvm_vcpu *vcpu)
+{
+#ifdef CONFIG_X86_64
+ return (vcpu->arch.efer & EFER_LMA) &&
+ kvm_read_cr4_bits(vcpu, X86_CR4_LA57);
+#else
+ return 0;
+#endif
+}
+
static inline bool mmu_is_nested(struct kvm_vcpu *vcpu)
{
return vcpu->arch.walk_mmu == &vcpu->arch.nested_mmu;
--
2.5.0