Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756970Ab0LMK0u (ORCPT ); Mon, 13 Dec 2010 05:26:50 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:49210 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753200Ab0LMK0s (ORCPT ); Mon, 13 Dec 2010 05:26:48 -0500 Message-ID: <4D05F5F6.3070909@cn.fujitsu.com> Date: Mon, 13 Dec 2010 18:31:18 +0800 From: Xiao Guangrong User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.11) Gecko/20100713 Thunderbird/3.0.6 MIME-Version: 1.0 To: Avi Kivity CC: Marcelo Tosatti , LKML , KVM Subject: [PATCH 1/2] KVM: MMU: don't make direct sp read-only if !map_writable X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2010-12-13 18:26:47, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2010-12-13 18:26:47, Serialize complete at 2010-12-13 18:26:47 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2590 Lines: 73 Currently, if the page is not allowed to write, then it can drop ACC_WRITE_MASK in pte_access, and the direct sp's access is: gw->pt_access & gw->pte_access so, it also removes the write access in the direct sp. There is a problem: if the access of those pages which map thought the same mapping in guest is different in host, it causes host switch direct sp very frequently. Signed-off-by: Xiao Guangrong --- arch/x86/kvm/mmu.c | 4 ++-- arch/x86/kvm/paging_tmpl.h | 11 ++--------- 2 files changed, 4 insertions(+), 11 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 1a953ac..0c5cad0 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1987,6 +1987,8 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, if (host_writable) spte |= SPTE_HOST_WRITEABLE; + else + pte_access &= ~ACC_WRITE_MASK; spte |= (u64)pfn << PAGE_SHIFT; @@ -2226,8 +2228,6 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write, if (iterator.level == level) { unsigned pte_access = ACC_ALL; - if (!map_writable) - pte_access &= ~ACC_WRITE_MASK; mmu_set_spte(vcpu, iterator.sptep, ACC_ALL, pte_access, 0, write, 1, &pt_write, level, gfn, pfn, prefault, map_writable); diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 146b681..6ed2c5e 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -593,9 +593,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code, if (is_error_pfn(pfn)) return kvm_handle_bad_page(vcpu->kvm, walker.gfn, pfn); - if (!map_writable) - walker.pte_access &= ~ACC_WRITE_MASK; - spin_lock(&vcpu->kvm->mmu_lock); if (mmu_notifier_retry(vcpu, mmu_seq)) goto out_unlock; @@ -809,12 +806,8 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) nr_present++; pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte); - if (!(sp->spt[i] & SPTE_HOST_WRITEABLE)) { - pte_access &= ~ACC_WRITE_MASK; - host_writable = 0; - } else { - host_writable = 1; - } + host_writable = !!(sp->spt[i] & SPTE_HOST_WRITEABLE); + set_spte(vcpu, &sp->spt[i], pte_access, 0, 0, is_dirty_gpte(gpte), PT_PAGE_TABLE_LEVEL, gfn, spte_to_pfn(sp->spt[i]), true, false, -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/