Bit 8 would be the "global" bit, which does not quite make sense for non-leaf
page table entries. Intel ignores it; AMD ignores it in PDEs, but reserves it
in PDPEs and PML4Es. The SVM test is relying on this behavior, so enforce it.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
arch/x86/kvm/cpuid.h | 8 ++++++++
arch/x86/kvm/mmu.c | 13 +++++++++++--
2 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index a5380590ab0e..43b33e301e68 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -88,6 +88,14 @@ static inline bool guest_cpuid_has_x2apic(struct kvm_vcpu
*vcpu)
return best && (best->ecx & bit(X86_FEATURE_X2APIC));
}
+static inline bool guest_cpuid_is_amd(struct kvm_vcpu *vcpu)
+{
+ struct kvm_cpuid_entry2 *best;
+
+ best = kvm_find_cpuid_entry(vcpu, 0, 0);
+ return best && best->ebx == X86EMUL_CPUID_VENDOR_AuthenticAMD_ebx;
+}
+
static inline bool guest_cpuid_has_gbpages(struct kvm_vcpu *vcpu)
{
struct kvm_cpuid_entry2 *best;
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 6b6df0c5be3d..5b93a597e0c8 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3512,6 +3512,7 @@ static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu,
int maxphyaddr = cpuid_maxphyaddr(vcpu);
u64 exb_bit_rsvd = 0;
u64 gbpages_bit_rsvd = 0;
+ u64 nonleaf_bit8_rsvd = 0;
context->bad_mt_xwr = 0;
@@ -3519,6 +3520,14 @@ static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu,
exb_bit_rsvd = rsvd_bits(63, 63);
if (!guest_cpuid_has_gbpages(vcpu))
gbpages_bit_rsvd = rsvd_bits(7, 7);
+
+ /*
+ * Non-leaf PML4Es and PDPEs reserve bit 8 (which would be the G bit for
+ * leaf entries) on AMD CPUs only.
+ */
+ if (guest_cpuid_is_amd(vcpu))
+ nonleaf_bit8_rsvd = rsvd_bits(8, 8);
+
switch (context->root_level) {
case PT32_ROOT_LEVEL:
/* no rsvd bits for 2 level 4K page table entries */
@@ -3553,9 +3562,9 @@ static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu,
break;
case PT64_ROOT_LEVEL:
context->rsvd_bits_mask[0][3] = exb_bit_rsvd |
- rsvd_bits(maxphyaddr, 51) | rsvd_bits(7, 7);
+ nonleaf_bit8_rsvd | rsvd_bits(7, 7) |
rsvd_bits(maxphyaddr, 51);
context->rsvd_bits_mask[0][2] = exb_bit_rsvd |
- gbpages_bit_rsvd | rsvd_bits(maxphyaddr, 51);
+ nonleaf_bit8_rsvd | gbpages_bit_rsvd |
rsvd_bits(maxphyaddr, 51);
context->rsvd_bits_mask[0][1] = exb_bit_rsvd |
rsvd_bits(maxphyaddr, 51);
context->rsvd_bits_mask[0][0] = exb_bit_rsvd |
--
1.8.3.1
--
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