Commit cbe1e6f0 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Incorporate guest's page level into max level for shadow MMU 



Restrict the max level for a shadow page based on the guest's level
instead of capping the level after the fact for host-mapped huge pages,
e.g. hugetlbfs pages.  Explicitly capping the max level using the guest
mapping level also eliminates FNAME(page_fault)'s subtle dependency on
THP only supporting 2mb pages.

No functional change intended.

Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 39ca1ecb

arch/x86/kvm/mmu/paging_tmpl.h

+8 −12
Original line number Diff line number Diff line
@@ -773,7 +773,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gpa_t addr, u32 error_code, 
	struct guest_walker walker;

	int r;

	kvm_pfn_t pfn;

	int level = PT_PAGE_TABLE_LEVEL;

	int level;

	unsigned long mmu_seq;

	bool map_writable, is_self_change_mapping;

	bool lpage_disallowed = (error_code & PFERR_FETCH_MASK) &&
@@ -818,18 +818,14 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gpa_t addr, u32 error_code, 
	is_self_change_mapping = FNAME(is_self_change_mapping)(vcpu,

	      &walker, user_fault, &vcpu->arch.write_fault_to_shadow_pgtable);



	max_level = lpage_disallowed ? PT_PAGE_TABLE_LEVEL :

				       PT_MAX_HUGEPAGE_LEVEL;

	if (lpage_disallowed || is_self_change_mapping)

		max_level = PT_PAGE_TABLE_LEVEL;

	else

		max_level = walker.level;



	if (walker.level >= PT_DIRECTORY_LEVEL && !is_self_change_mapping) {

	level = mapping_level(vcpu, walker.gfn, &max_level);

		if (likely(max_level > PT_DIRECTORY_LEVEL)) {

			level = min(walker.level, level);

	if (level > PT_PAGE_TABLE_LEVEL)

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

		}

	} else {

		max_level = PT_PAGE_TABLE_LEVEL;

	}



	mmu_seq = vcpu->kvm->mmu_notifier_seq;

	smp_rmb();