From: Sean Christopherson Date: Fri, 6 Dec 2019 23:57:21 +0000 (-0800) Subject: KVM: x86/mmu: Incorporate guest's page level into max level for shadow MMU X-Git-Tag: v5.6-rc1~106^2~142 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=cbe1e6f035523b5fd29e44e18b82081b33d1f3f3;p=linux-block.git 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: Sean Christopherson Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index 1938a6e4e631..7d57ec576df0 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -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 (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); - walker.gfn = walker.gfn & ~(KVM_PAGES_PER_HPAGE(level) - 1); - } - } else { + if (lpage_disallowed || is_self_change_mapping) max_level = PT_PAGE_TABLE_LEVEL; - } + else + max_level = walker.level; + + level = mapping_level(vcpu, walker.gfn, &max_level); + if (level > PT_PAGE_TABLE_LEVEL) + walker.gfn = walker.gfn & ~(KVM_PAGES_PER_HPAGE(level) - 1); mmu_seq = vcpu->kvm->mmu_notifier_seq; smp_rmb();