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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 35656C3DA4A for ; Sat, 27 Jul 2024 00:17:29 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20230601 header.b=0ZGdfqNM; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4WW4vC6SyRz3cBb for ; Sat, 27 Jul 2024 10:17:27 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20230601 header.b=0ZGdfqNM; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=flex--seanjc.bounces.google.com (client-ip=2607:f8b0:4864:20::44a; helo=mail-pf1-x44a.google.com; envelope-from=3dtekzgykdeg2okxtmqyyqvo.mywvsx47zzm-no5vs232.y9vkl2.y1q@flex--seanjc.bounces.google.com; receiver=lists.ozlabs.org) Received: from mail-pf1-x44a.google.com (mail-pf1-x44a.google.com [IPv6:2607:f8b0:4864:20::44a]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4WW4Mz32pGz3dWW for ; Sat, 27 Jul 2024 09:53:51 +1000 (AEST) Received: by mail-pf1-x44a.google.com with SMTP id d2e1a72fcca58-70d19a4137dso1423097b3a.1 for ; Fri, 26 Jul 2024 16:53:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1722038030; x=1722642830; darn=lists.ozlabs.org; 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=Xse5B7AOfcqAOlY7bR5VB/olShqjuvoHnQg+aILML2Y=; b=0ZGdfqNMc7/c0a4qPYlIn0RA4zrXDs7ZAgcYudLFh5TmOCPCr5ZBqiHkyubCaZNZwG Zhq11mzQwc95aUiyZYSZDlpUGrbb+0Xj1I1KLG39TFukqz3SzU6v1eTjyrQCvz6s9QgF /+ZAMwuYzJ46FlCQ27gLX7eYDBwoH6HCFR3OwRUHk38o8RTyovHdw8aW2YwBgL92EO1g iiw8ndiH/2rgaMLELIUFBIKDi6EOsJCxp2kyNGJz4baQcLZmhSXGlR6r4dpc682yRXx2 kG+gUx6b5DZHN4o8ztQhUvM0APnAiRIoilqT+3g01MTW6stko0rcjDBKHXZl8s4JK6vM 54yg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722038030; x=1722642830; 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=Xse5B7AOfcqAOlY7bR5VB/olShqjuvoHnQg+aILML2Y=; b=kxYxojqpEKKLb/GeYnQYWMs6vKweoV2I4WJrv0Fv1GcA1Gqm6nz82S1yBOzTligbSu UoN63hCX/i+qkqfi0G8KiOem+jhrVgP/H7JjucwFl6RUifLxwChxUFrkJ6hyC/7kuFg3 lXEuGXg6/iay7TobvOcLt4qD0ItaRQyEmg09AKKLbse4ZV1wRB7YYWivY8T4/tEWUxG3 HM2T2mD7zuDotHRT8wUuwjVp/EHj1aHDQ2FU1LRJj4Wur5UWwgl0fvmn+wltQC7Eqtk/ 2Dc2TJ5kx1/gsAX4g5o7wJwnf0xwj/caiGCJyfjBnljsYud2esF9JvqfVRF0kxMuE7cR G6ow== X-Forwarded-Encrypted: i=1; AJvYcCVW0wMedGhkv8TO8gxCQi1qk1nFQjG6KpvptFgOPhSwQz0sg8Zn4nleEwv5rkFYwjlFTNSqdyrLgdKjx8H8tt5Oj9sWXpkOCdg+IPmJzA== X-Gm-Message-State: AOJu0YxusEfsIEq0n/oJ2ZkoraUz0xSLKyGeaP7DYteWTJQndwRdreUS 4xswczWdpYAEIfgZtWRbvY63jf3PRBt+ouDqNgsDbvsZe16uFNg9FfLxIbCBArj8DtoiSI8VX6W Orw== X-Google-Smtp-Source: AGHT+IEFcNwoZPtxzQ32cLJ1vxa7gkQJVcgltXDXIuLlGv+WV+Ss10kIc9nwtzcNKm3zIIgT6vAGf5Ndk9o= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6a00:2e2a:b0:70d:9a0e:c13b with SMTP id d2e1a72fcca58-70ece7f0562mr55820b3a.3.1722038029490; Fri, 26 Jul 2024 16:53:49 -0700 (PDT) Date: Fri, 26 Jul 2024 16:51:44 -0700 In-Reply-To: <20240726235234.228822-1-seanjc@google.com> Mime-Version: 1.0 References: <20240726235234.228822-1-seanjc@google.com> X-Mailer: git-send-email 2.46.0.rc1.232.g9752f9e123-goog Message-ID: <20240726235234.228822-36-seanjc@google.com> Subject: [PATCH v12 35/84] KVM: x86: Use kvm_lookup_pfn() to check if retrying #PF is useful From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Sean Christopherson Content-Type: text/plain; charset="UTF-8" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Sean Christopherson Cc: kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, David Matlack , David Stevens , loongarch@lists.linux.dev, kvmarm@lists.linux.dev, linux-riscv@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Use kvm_lookup_pfn() instead of an open coded equivalent when checking to see if KVM should exit to userspace or re-enter the guest after failed instruction emulation triggered by a guest page fault. Note, there is a small functional change as kvm_lookup_pfn() doesn't mark the page as accessed, whereas kvm_release_pfn_clean() does mark the page accessed (if the pfn is backed by a refcounted struct page). Neither behavior is wrong per se, e.g. querying the gfn=>pfn mapping doesn't actually access the page, but the guest _did_ access the gfn, otherwise the fault wouldn't have occurred. That said, either KVM will exit to userspace and the guest will likely be terminated, or KVM will re-enter the guest and, barring weirdness in the guest, the guest will re-access the gfn, and KVM will fault-in the pfn and mark it accessed. Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index af6c8cf6a37a..59501ad6e7f5 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8867,7 +8867,6 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, int emulation_type) { gpa_t gpa = cr2_or_gpa; - kvm_pfn_t pfn; if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF)) return false; @@ -8892,22 +8891,15 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, } /* - * Do not retry the unhandleable instruction if it faults on the - * readonly host memory, otherwise it will goto a infinite loop: + * Do not retry the unhandleable instruction if emulation was triggered + * for emulated MMIO, e.g. by a readonly memslot or lack of a memslot, + * otherwise KVM will send the vCPU into an infinite loop: * retry instruction -> write #PF -> emulation fail -> retry * instruction -> ... */ - pfn = gfn_to_pfn(vcpu->kvm, gpa_to_gfn(gpa)); - - /* - * If the instruction failed on the error pfn, it can not be fixed, - * report the error to userspace. - */ - if (is_error_noslot_pfn(pfn)) + if (is_error_noslot_pfn(kvm_lookup_pfn(vcpu->kvm, gpa_to_gfn(gpa)))) return false; - kvm_release_pfn_clean(pfn); - /* * If emulation may have been triggered by a write to a shadowed page * table, unprotect the gfn (zap any relevant SPTEs) and re-enter the -- 2.46.0.rc1.232.g9752f9e123-goog