From nobody Tue Apr 7 07:55:40 2026 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 D7E23C43217 for ; Wed, 12 Oct 2022 18:17:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229867AbiJLSRw (ORCPT ); Wed, 12 Oct 2022 14:17:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44182 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229775AbiJLSRe (ORCPT ); Wed, 12 Oct 2022 14:17:34 -0400 Received: from mail-pg1-x549.google.com (mail-pg1-x549.google.com [IPv6:2607:f8b0:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A80D29816 for ; Wed, 12 Oct 2022 11:17:20 -0700 (PDT) Received: by mail-pg1-x549.google.com with SMTP id y71-20020a638a4a000000b0046014b2258dso6317229pgd.19 for ; Wed, 12 Oct 2022 11:17:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=vUaKgOSrNqA1/LJ+9txEymrprt2AYNUfSfOocHXnnPA=; b=TV0tYpUJlzj2DrhD9CPl8P8ic32L5Cbn5gVvBySQmsBGKCWVfG/vcVj5z05yHAhWrp ApMxT74hLkEBLq0mgx7MSBPwckA2eLstZXh4/ld9M+3YxQmZr4iqyt02J8G1WQGsTkgN Qp0Ed+FCdo0f1eMzfRJp+RWra39O62tVUChPlg+7NaJorCjiNPVPXJ1lJpCmXUCcqPcm R3y4xSbjX/YUgQ4UIr1A6LDN/47mgjF7KcNjK90T0hzJBBv0NMsN+lS28ijCFjYgELv3 jL+I6IIQO7w3Qhwux1iTqvyz7754thhuT4lPavt2CtcEXFsggzpipPE6vNOMnIUgEP4e 6haQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=vUaKgOSrNqA1/LJ+9txEymrprt2AYNUfSfOocHXnnPA=; b=c5FNlX7jm50BOkuyu+ALjDGVfFvdizKYXeGXQFdARz265/uMsxc0Z6rZPqSafLo4G/ Qps8ah3NZdcnu4wX6STJotFtfTN8XoUddVu97ZpaGXCu88YCjvbwBnlRQIsYLQfobZqh VfHqDcgXQo1rvfv/ZeO8thQV7DStRDN2VfizxxNSkrGwZU4s5GeLVbHD4ksXIBriD0Wf Xh57dNYu3+9+TcczfhhsJ/PMVRED4zrBoj7mJYGEjRUB+gi2nZDDwpeO/PfGFzeuguCw D7g8HaZU6GANgp4bcPcmRK6HjFFJ0IOZlJC5kxera1pc0BMVrCQcs/2ydKA7F5kmWeEg N2YQ== X-Gm-Message-State: ACrzQf2ejo6+l7GINxu+2UiSn5z8Ptz9DeIRfRvyGVS9YxL7axSjmFpg AZYbcPakeJcoux3y5vRPg3+RX/m6rkc= X-Google-Smtp-Source: AMsMyM6NLKMVWBVhxXqpNktOPLqijNknlgx85gWq5Yox6xkv3aBfx4K5CAJNFODuB42nFrQQgU5CYvEAXaI= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a17:90b:4b0c:b0:20d:7ffa:4b1b with SMTP id lx12-20020a17090b4b0c00b0020d7ffa4b1bmr6560072pjb.16.1665598637830; Wed, 12 Oct 2022 11:17:17 -0700 (PDT) Reply-To: Sean Christopherson Date: Wed, 12 Oct 2022 18:16:57 +0000 In-Reply-To: <20221012181702.3663607-1-seanjc@google.com> Mime-Version: 1.0 References: <20221012181702.3663607-1-seanjc@google.com> X-Mailer: git-send-email 2.38.0.rc1.362.ged0d419d3c-goog Message-ID: <20221012181702.3663607-7-seanjc@google.com> Subject: [PATCH v4 06/11] KVM: x86/mmu: Handle no-slot faults in kvm_faultin_pfn() From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, David Matlack , Isaku Yamahata Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: David Matlack Handle faults on GFNs that do not have a backing memslot in kvm_faultin_pfn() and drop handle_abnormal_pfn(). This eliminates duplicate code in the various page fault handlers. Opportunistically tweak the comment about handling gfn > host.MAXPHYADDR to reflect that the effect of returning RET_PF_EMULATE at that point is to avoid creating an MMIO SPTE for such GFNs. No functional change intended. Signed-off-by: David Matlack Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu/mmu.c | 56 ++++++++++++++++++---------------- arch/x86/kvm/mmu/paging_tmpl.h | 6 +--- 2 files changed, 31 insertions(+), 31 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 07c3f83b3204..5710be4d328b 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3175,28 +3175,32 @@ static int kvm_handle_error_pfn(struct kvm_page_fau= lt *fault) return -EFAULT; } =20 -static int handle_abnormal_pfn(struct kvm_vcpu *vcpu, struct kvm_page_faul= t *fault, - unsigned int access) +static int kvm_handle_noslot_fault(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault, + unsigned int access) { - if (unlikely(!fault->slot)) { - gva_t gva =3D fault->is_tdp ? 0 : fault->addr; + gva_t gva =3D fault->is_tdp ? 0 : fault->addr; =20 - vcpu_cache_mmio_info(vcpu, gva, fault->gfn, - access & shadow_mmio_access_mask); - /* - * If MMIO caching is disabled, emulate immediately without - * touching the shadow page tables as attempting to install an - * MMIO SPTE will just be an expensive nop. Do not cache MMIO - * whose gfn is greater than host.MAXPHYADDR, any guest that - * generates such gfns is running nested and is being tricked - * by L0 userspace (you can observe gfn > L1.MAXPHYADDR if - * and only if L1's MAXPHYADDR is inaccurate with respect to - * the hardware's). - */ - if (unlikely(!enable_mmio_caching) || - unlikely(fault->gfn > kvm_mmu_max_gfn())) - return RET_PF_EMULATE; - } + vcpu_cache_mmio_info(vcpu, gva, fault->gfn, + access & shadow_mmio_access_mask); + + /* + * If MMIO caching is disabled, emulate immediately without + * touching the shadow page tables as attempting to install an + * MMIO SPTE will just be an expensive nop. + */ + if (unlikely(!enable_mmio_caching)) + return RET_PF_EMULATE; + + /* + * Do not create an MMIO SPTE for a gfn greater than host.MAXPHYADDR, + * any guest that generates such gfns is running nested and is being + * tricked by L0 userspace (you can observe gfn > L1.MAXPHYADDR if and + * only if L1's MAXPHYADDR is inaccurate with respect to the + * hardware's). + */ + if (unlikely(fault->gfn > kvm_mmu_max_gfn())) + return RET_PF_EMULATE; =20 return RET_PF_CONTINUE; } @@ -4197,7 +4201,8 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, s= truct kvm_page_fault *fault return RET_PF_CONTINUE; } =20 -static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *f= ault) +static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *f= ault, + unsigned int access) { int ret; =20 @@ -4211,6 +4216,9 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, str= uct kvm_page_fault *fault) if (unlikely(is_error_pfn(fault->pfn))) return kvm_handle_error_pfn(fault); =20 + if (unlikely(!fault->slot)) + return kvm_handle_noslot_fault(vcpu, fault, access); + return RET_PF_CONTINUE; } =20 @@ -4261,11 +4269,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, = struct kvm_page_fault *fault if (r) return r; =20 - r =3D kvm_faultin_pfn(vcpu, fault); - if (r !=3D RET_PF_CONTINUE) - return r; - - r =3D handle_abnormal_pfn(vcpu, fault, ACC_ALL); + r =3D kvm_faultin_pfn(vcpu, fault, ACC_ALL); if (r !=3D RET_PF_CONTINUE) return r; =20 diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index 30b9d9b6734f..60bd642bbb90 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -837,11 +837,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, st= ruct kvm_page_fault *fault else fault->max_level =3D walker.level; =20 - r =3D kvm_faultin_pfn(vcpu, fault); - if (r !=3D RET_PF_CONTINUE) - return r; - - r =3D handle_abnormal_pfn(vcpu, fault, walker.pte_access); + r =3D kvm_faultin_pfn(vcpu, fault, walker.pte_access); if (r !=3D RET_PF_CONTINUE) return r; =20 --=20 2.38.0.rc1.362.ged0d419d3c-goog