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KVM: x86/mmu: Print SPTEs on unexpected #VE

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Print the SPTEs that correspond to the faulting GPA on an unexpected EPT
Violation #VE to help the user debug failures, e.g. to pinpoint which SPTE
didn't have SUPPRESS_VE set.

Opportunistically assert that the underlying exit reason was indeed an EPT
Violation, as the CPU has *really* gone off the rails if a #VE occurs due
to a completely unexpected exit reason.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20240518000430.1118488-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2024-05-17 17:04:27 -07:00 committed by Paolo Bonzini
parent 743f177336
commit bca99c0356
3 changed files with 39 additions and 9 deletions
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1
arch/x86/include/asm/kvm_host.h
View file

@ -2154,6 +2154,7 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu);
int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
void *insn, int insn_len);
void kvm_mmu_print_sptes(struct kvm_vcpu *vcpu, gpa_t gpa, const char *msg);
void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva);
void kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
u64 addr, unsigned long roots);

42
arch/x86/kvm/mmu/mmu.c
View file

@ -4104,6 +4104,22 @@ static int get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level
return leaf;
}
static int get_sptes_lockless(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes,
int *root_level)
{
int leaf;
walk_shadow_page_lockless_begin(vcpu);
if (is_tdp_mmu_active(vcpu))
leaf = kvm_tdp_mmu_get_walk(vcpu, addr, sptes, root_level);
else
leaf = get_walk(vcpu, addr, sptes, root_level);
walk_shadow_page_lockless_end(vcpu);
return leaf;
}
/* return true if reserved bit(s) are detected on a valid, non-MMIO SPTE. */
static bool get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep)
{
@ -4112,15 +4128,7 @@ static bool get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep)
int root, leaf, level;
bool reserved = false;
walk_shadow_page_lockless_begin(vcpu);
if (is_tdp_mmu_active(vcpu))
leaf = kvm_tdp_mmu_get_walk(vcpu, addr, sptes, &root);
else
leaf = get_walk(vcpu, addr, sptes, &root);
walk_shadow_page_lockless_end(vcpu);
leaf = get_sptes_lockless(vcpu, addr, sptes, &root);
if (unlikely(leaf < 0)) {
*sptep = 0ull;
return reserved;
@ -5924,6 +5932,22 @@ int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 err
}
EXPORT_SYMBOL_GPL(kvm_mmu_page_fault);
void kvm_mmu_print_sptes(struct kvm_vcpu *vcpu, gpa_t gpa, const char *msg)
{
u64 sptes[PT64_ROOT_MAX_LEVEL + 1];
int root_level, leaf, level;
leaf = get_sptes_lockless(vcpu, gpa, sptes, &root_level);
if (unlikely(leaf < 0))
return;
pr_err("%s %llx", msg, gpa);
for (level = root_level; level >= leaf; level--)
pr_cont(", spte[%d] = 0x%llx", level, sptes[level]);
pr_cont("\n");
}
EXPORT_SYMBOL_GPL(kvm_mmu_print_sptes);
static void __kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
u64 addr, hpa_t root_hpa)
{

5
arch/x86/kvm/vmx/vmx.c
View file

@ -5218,7 +5218,12 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
return handle_ud(vcpu);
if (WARN_ON_ONCE(is_ve_fault(intr_info))) {
struct vmx_ve_information *ve_info = vmx->ve_info;
WARN_ONCE(ve_info->exit_reason != EXIT_REASON_EPT_VIOLATION,
"Unexpected #VE on VM-Exit reason 0x%x", ve_info->exit_reason);
dump_vmcs(vcpu);
kvm_mmu_print_sptes(vcpu, ve_info->guest_physical_address, "#VE");
return 1;
}