Commit f9fa2509 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Drop level optimization from fast_page_fault() 



Remove fast_page_fault()'s optimization to stop the shadow walk if the
iterator level drops below the intended map level.  The intended map
level is only acccurate for HugeTLB mappings (THP mappings are detected
after fast_page_fault()), i.e. it's not required for correctness, and
a future patch will also move HugeTLB mapping detection to after
fast_page_fault().

Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent db543216

arch/x86/kvm/mmu/mmu.c

+3 −4
Original line number Diff line number Diff line
@@ -3586,7 +3586,7 @@ static bool is_access_allowed(u32 fault_err_code, u64 spte) 
 * - true: let the vcpu to access on the same address again.

 * - false: let the real page fault path to fix it.

 */

static bool fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, int level,

static bool fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,

			    u32 error_code)

{

	struct kvm_shadow_walk_iterator iterator;
@@ -3604,8 +3604,7 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, int level, 
		u64 new_spte;



		for_each_shadow_entry_lockless(vcpu, cr2_or_gpa, iterator, spte)

			if (!is_shadow_present_pte(spte) ||

			    iterator.level < level)

			if (!is_shadow_present_pte(spte))

				break;



		sp = page_header(__pa(iterator.sptep));
@@ -4218,7 +4217,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, 
	if (level > PT_PAGE_TABLE_LEVEL)

		gfn &= ~(KVM_PAGES_PER_HPAGE(level) - 1);



	if (fast_page_fault(vcpu, gpa, level, error_code))

	if (fast_page_fault(vcpu, gpa, error_code))

		return RET_PF_RETRY;



	mmu_seq = vcpu->kvm->mmu_notifier_seq;

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