From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: KVM: MMU: remove prefault from invlpg handler Date: Sat, 5 Dec 2009 12:34:11 -0200 Message-ID: <20091205143411.GA16237@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm To: Avi Kivity Return-path: Received: from mx1.redhat.com ([209.132.183.28]:23899 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755343AbZLEOeV (ORCPT ); Sat, 5 Dec 2009 09:34:21 -0500 Received: from int-mx03.intmail.prod.int.phx2.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.16]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id nB5EYSD2003522 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Sat, 5 Dec 2009 09:34:28 -0500 Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: The invlpg prefault optimization breaks Windows 2008 R2 occasionally. The visible effect is that the invlpg handler instantiates a pte which is, microseconds later, written with a different gfn by another vcpu. The OS could have other mechanisms to prevent a present translation from being used, which the hypervisor is unaware of. Fix by making invlpg emulation follow documented behaviour. Signed-off-by: Marcelo Tosatti diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index a601713..58a0f1e 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -455,8 +455,6 @@ out_unlock: static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) { struct kvm_shadow_walk_iterator iterator; - pt_element_t gpte; - gpa_t pte_gpa = -1; int level; u64 *sptep; int need_flush = 0; @@ -470,10 +468,6 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) if (level == PT_PAGE_TABLE_LEVEL || ((level == PT_DIRECTORY_LEVEL && is_large_pte(*sptep))) || ((level == PT_PDPE_LEVEL && is_large_pte(*sptep)))) { - struct kvm_mmu_page *sp = page_header(__pa(sptep)); - - pte_gpa = (sp->gfn << PAGE_SHIFT); - pte_gpa += (sptep - sp->spt) * sizeof(pt_element_t); if (is_shadow_present_pte(*sptep)) { rmap_remove(vcpu->kvm, sptep); @@ -492,18 +486,6 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) if (need_flush) kvm_flush_remote_tlbs(vcpu->kvm); spin_unlock(&vcpu->kvm->mmu_lock); - - if (pte_gpa == -1) - return; - if (kvm_read_guest_atomic(vcpu->kvm, pte_gpa, &gpte, - sizeof(pt_element_t))) - return; - if (is_present_gpte(gpte) && (gpte & PT_ACCESSED_MASK)) { - if (mmu_topup_memory_caches(vcpu)) - return; - kvm_mmu_pte_write(vcpu, pte_gpa, (const u8 *)&gpte, - sizeof(pt_element_t), 0); - } } static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)