d0ec49d ("kvm/x86/svm: Support Secure Memory Encryption within KVM")
uses __sme_clr() to remove the C-bit in rsvd_bits(). rsvd_bits() is
just a simple function to return some 1 bits. Applying a mask based
on properties of the host MMU is incorrect. Additionally, the masks
computed by __reset_rsvds_bits_mask also apply to guest page tables,
where the C bit is reserved since we don't emulate SME.
The fix is to clear the C-bit from rsvd_bits_mask array after it has been
populated from __reset_rsvds_bits_mask()
Acked-by: Paolo Bonzini <pbonz...@redhat.com>
Cc: Tom Lendacky <thomas.lenda...@amd.com>
Cc: Stephen Rothwell <s...@canb.auug.org.au>
Cc: Paolo Bonzini <pbonz...@redhat.com>
Cc: Radim Krčmář <rkrc...@redhat.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: H. Peter Anvin <h...@zytor.com>
Cc: Ingo Molnar <mi...@elte.hu>
Cc: Peter Zijlstra <pet...@infradead.org>
Suggested-by: Paolo Bonzini <pbonz...@redhat.com>
Fixes: d0ec49d ("kvm/x86/svm: Support Secure Memory Encryption within KVM")
Signed-off-by: Brijesh Singh <brijesh.si...@amd.com>
---
arch/x86/kvm/mmu.c | 30 +++++++++++++++++++++++++++---
arch/x86/kvm/mmu.h | 2 +-
2 files changed, 28 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index ccb70b8..04d7508 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4109,16 +4109,28 @@ void
reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context)
{
bool uses_nx = context->nx || context->base_role.smep_andnot_wp;
+ struct rsvd_bits_validate *shadow_zero_check;
+ int i;
/*
* Passing "true" to the last argument is okay; it adds a check
* on bit 8 of the SPTEs which KVM doesn't use anyway.
*/
- __reset_rsvds_bits_mask(vcpu, &context->shadow_zero_check,
+ shadow_zero_check = &context->shadow_zero_check;
+ __reset_rsvds_bits_mask(vcpu, shadow_zero_check,
boot_cpu_data.x86_phys_bits,
context->shadow_root_level, uses_nx,
guest_cpuid_has_gbpages(vcpu), is_pse(vcpu),
true);
+
+ if (!shadow_me_mask)
+ return;
+
+ for (i = context->shadow_root_level; --i >= 0;) {
+ shadow_zero_check->rsvd_bits_mask[0][i] &= ~shadow_me_mask;
+ shadow_zero_check->rsvd_bits_mask[1][i] &= ~shadow_me_mask;
+ }
+
}
EXPORT_SYMBOL_GPL(reset_shadow_zero_bits_mask);
@@ -4136,17 +4148,29 @@ static void
reset_tdp_shadow_zero_bits_mask(struct kvm_vcpu *vcpu,
struct kvm_mmu *context)
{
+ struct rsvd_bits_validate *shadow_zero_check;
+ int i;
+
+ shadow_zero_check = &context->shadow_zero_check;
+
if (boot_cpu_is_amd())
- __reset_rsvds_bits_mask(vcpu, &context->shadow_zero_check,
+ __reset_rsvds_bits_mask(vcpu, shadow_zero_check,
boot_cpu_data.x86_phys_bits,
context->shadow_root_level, false,
boot_cpu_has(X86_FEATURE_GBPAGES),
true, true);
else
- __reset_rsvds_bits_mask_ept(&context->shadow_zero_check,
+ __reset_rsvds_bits_mask_ept(shadow_zero_check,
boot_cpu_data.x86_phys_bits,
false);
+ if (!shadow_me_mask)
+ return;
+
+ for (i = context->shadow_root_level; --i >= 0;) {
+ shadow_zero_check->rsvd_bits_mask[0][i] &= ~shadow_me_mask;
+ shadow_zero_check->rsvd_bits_mask[1][i] &= ~shadow_me_mask;
+ }
}
/*
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 3cc7255..d7d248a 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -48,7 +48,7 @@
static inline u64 rsvd_bits(int s, int e)
{
- return __sme_clr(((1ULL << (e - s + 1)) - 1) << s);
+ return ((1ULL << (e - s + 1)) - 1) << s;
}
void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask, u64 mmio_value);
--
2.9.4
