Commit bca99c03 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

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



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: default avatarSean Christopherson <seanjc@google.com>
Message-ID: <20240518000430.1118488-7-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 743f1773

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/kvm/mmu/mmu.c

+32 −8
Original line number Diff line number Diff line
@@ -4104,23 +4104,31 @@ static int get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level 
	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)

static int get_sptes_lockless(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes,

			      int *root_level)

{

	u64 sptes[PT64_ROOT_MAX_LEVEL + 1];

	struct rsvd_bits_validate *rsvd_check;

	int root, leaf, level;

	bool reserved = false;

	int leaf;



	walk_shadow_page_lockless_begin(vcpu);



	if (is_tdp_mmu_active(vcpu))

		leaf = kvm_tdp_mmu_get_walk(vcpu, addr, sptes, &root);

		leaf = kvm_tdp_mmu_get_walk(vcpu, addr, sptes, root_level);

	else

		leaf = get_walk(vcpu, addr, sptes, &root);

		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)

{

	u64 sptes[PT64_ROOT_MAX_LEVEL + 1];

	struct rsvd_bits_validate *rsvd_check;

	int root, leaf, level;

	bool reserved = false;



	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)

{

arch/x86/kvm/vmx/vmx.c

+5 −0
Original line number Diff line number Diff line
@@ -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;

	}