From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2A92C433F5 for ; Tue, 23 Nov 2021 09:34:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233877AbhKWJhq (ORCPT ); Tue, 23 Nov 2021 04:37:46 -0500 Received: from out30-44.freemail.mail.aliyun.com ([115.124.30.44]:46518 "EHLO out30-44.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230286AbhKWJhq (ORCPT ); Tue, 23 Nov 2021 04:37:46 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R791e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=laijs@linux.alibaba.com;NM=1;PH=DS;RN=14;SR=0;TI=SMTPD_---0UxueP3J_1637660074; Received: from 30.22.113.103(mailfrom:laijs@linux.alibaba.com fp:SMTPD_---0UxueP3J_1637660074) by smtp.aliyun-inc.com(127.0.0.1); Tue, 23 Nov 2021 17:34:35 +0800 Message-ID: <31a86235-dd24-5215-907b-c05e356dee38@linux.alibaba.com> Date: Tue, 23 Nov 2021 17:34:34 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.2.1 Subject: Re: [PATCH 17/15] KVM: X86: Ensure pae_root to be reconstructed for shadow paging if the guest PDPTEs is changed Content-Language: en-US To: Lai Jiangshan , linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" References: <20211108124407.12187-1-jiangshanlai@gmail.com> <20211111144634.88972-1-jiangshanlai@gmail.com> From: Lai Jiangshan In-Reply-To: <20211111144634.88972-1-jiangshanlai@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hello, Paolo any thought/concern about this one? Thanks Lai On 2021/11/11 22:46, Lai Jiangshan wrote: > From: Lai Jiangshan > > For shadow paging, the pae_root needs to be reconstructed before the > coming VMENTER if the guest PDPTEs is changed. > > But not all paths that call load_pdptrs() will cause the pae_root to be > reconstructed. Normally, kvm_mmu_reset_context() and kvm_mmu_free_roots() > are used to launch later reconstruction. > > The commit d81135a57aa6("KVM: x86: do not reset mmu if CR0.CD and > CR0.NW are changed") skips kvm_mmu_reset_context() after load_pdptrs() > when changing CR0.CD and CR0.NW. > > The commit 21823fbda552("KVM: x86: Invalidate all PGDs for the current > PCID on MOV CR3 w/ flush") skips kvm_mmu_free_roots() after > load_pdptrs() when rewriting the CR3 with the same value. > > The commit a91a7c709600("KVM: X86: Don't reset mmu context when > toggling X86_CR4_PGE") skips kvm_mmu_reset_context() after > load_pdptrs() when changing CR4.PGE. > > Normally, the guest doesn't change the PDPTEs before doing only the > above operation without touching other bits that can force pae_root to > be reconstructed. Guests like linux would keep the PDPTEs unchaged > for every instance of pagetable. > > Fixes: d81135a57aa6("KVM: x86: do not reset mmu if CR0.CD and CR0.NW are changed") > Fixes: 21823fbda552("KVM: x86: Invalidate all PGDs for the current PCID on MOV CR3 w/ flush") > Fixes: a91a7c709600("KVM: X86: Don't reset mmu context when toggling X86_CR4_PGE") > Signed-off-by: Lai Jiangshan > --- > arch/x86/kvm/x86.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 0176eaa86a35..cfba337e46ab 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -832,8 +832,14 @@ int load_pdptrs(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, unsigned long cr3) > if (memcmp(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs))) { > memcpy(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs)); > kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR); > - /* Ensure the dirty PDPTEs to be loaded. */ > - kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu); > + /* > + * Ensure the dirty PDPTEs to be loaded for VMX with EPT > + * enabled or pae_root to be reconstructed for shadow paging. > + */ > + if (tdp_enabled) > + kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu); > + else > + kvm_mmu_free_roots(vcpu, vcpu->arch.mmu, KVM_MMU_ROOT_CURRENT); > } > vcpu->arch.pdptrs_from_userspace = false; > >