From patchwork Sun Nov 5 16:30:19 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13445993 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 485B2C4167D for ; Sun, 5 Nov 2023 16:33:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=XGnpUdpOGBV/w4gmmQXgjwBYUXVTI09ghmihgyKWsUw=; b=gmcatTw+5R1pao uDZMYb6rlODqajvQCSN7S6ipJs3ge9Ii8XuyXi0XmTS1Bzm1SrqNUGI2+RHnb+ITGrJ4mj3yib72+ sy3ScsW77dNlXzbos1xPn84wP9MlNr50aLn3PO5caEv2E3ArmfeYKyF3mvXDInXihOOZdW0Hcpqh3 GeeDPWDK4PySD2RZavjWcj0U5PjUH+vLN9nDkZiDgAqMINjSa9lDYyVBXsdlm3Q+hCOubaR8HYTii 0lJvT3Qi44FlyI7cwKKO5ulxd49kWM/z4qDLTsqCnRqYDo63vvuHF7IGmuZPhd4r0REzDqUslqnR2 00/1rQQR56Dbb27rk84w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qzg42-00FDPw-2o; Sun, 05 Nov 2023 16:33:30 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qzg3v-00FDGo-22 for linux-riscv@bombadil.infradead.org; Sun, 05 Nov 2023 16:33:23 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:Content-Type :MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Sender:Reply-To:Content-ID:Content-Description; bh=/uJI+ktz023TpGUQ2S26wAEUImlf4SsMQChBB/pSoBc=; b=X+jDg8DUqix4GhrrhL9NDZyrMt fDyYkkCgaZ1soNCHfWXAwicl1f507SoMQdqDfl8gYcnXuz5Y3BqrZy9fsXPHdgzN4BzVCLnZj+ZwR nowKx5tZzLzVtTsZv6SFrHRIxlWYQ9V6qGAg5AXZ/uDnJhWPz6X0bgaKG+xmEHCm08DorLbnHn5ev 0bBWQTUDeey19uSZVz8PFEhw3PI4DMAwhxew3yheHthXan0EW8Tbkbpm/VlhSXID1udtRQU+nuU1P Q0lbQh5GbX/RSSdU6Rzjnt8cCpmUq7TDWqG1UwUwPpfS6brGwJhIBb4wDKUSY1AGyW8EDNG/ANbE5 fRZTYQrQ==; Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by desiato.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qzg3g-009dZX-2Q for linux-riscv@lists.infradead.org; Sun, 05 Nov 2023 16:33:22 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1699201979; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/uJI+ktz023TpGUQ2S26wAEUImlf4SsMQChBB/pSoBc=; b=WHQW2+66oeNaMalcmWBAM4ENIJ6K++16JoOdpEDCXrxeVGEfDStJR5iKKR3CyvYGBBpCcc 5cfaBV70j78NylSVNhFMGV0NLcmj3QNzuMgIHygQqmdrEWxwAe7m3jMd15HjX0Wy+ixk0k uqs+VB6VZz/co5kjiCJJMJHLhP7QhMI= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1699201979; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/uJI+ktz023TpGUQ2S26wAEUImlf4SsMQChBB/pSoBc=; b=WHQW2+66oeNaMalcmWBAM4ENIJ6K++16JoOdpEDCXrxeVGEfDStJR5iKKR3CyvYGBBpCcc 5cfaBV70j78NylSVNhFMGV0NLcmj3QNzuMgIHygQqmdrEWxwAe7m3jMd15HjX0Wy+ixk0k uqs+VB6VZz/co5kjiCJJMJHLhP7QhMI= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-607-8MBsWsOoPKueD2L7R-1tiA-1; Sun, 05 Nov 2023 11:32:56 -0500 X-MC-Unique: 8MBsWsOoPKueD2L7R-1tiA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2F691810FC3; Sun, 5 Nov 2023 16:32:54 +0000 (UTC) Received: from avogadro.redhat.com (unknown [10.39.192.93]) by smtp.corp.redhat.com (Postfix) with ESMTP id 620112166B26; Sun, 5 Nov 2023 16:32:47 +0000 (UTC) From: Paolo Bonzini To: Paolo Bonzini , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Sean Christopherson , Alexander Viro , Christian Brauner , "Matthew Wilcox (Oracle)" , Andrew Morton Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Xiaoyao Li , Xu Yilun , Chao Peng , Fuad Tabba , Jarkko Sakkinen , Anish Moorthy , David Matlack , Yu Zhang , Isaku Yamahata , =?utf-8?q?Micka=C3=ABl_Sala?= =?utf-8?q?=C3=BCn?= , Vlastimil Babka , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A. Shutemov" Subject: [PATCH 16/34] KVM: x86: "Reset" vcpu->run->exit_reason early in KVM_RUN Date: Sun, 5 Nov 2023 17:30:19 +0100 Message-ID: <20231105163040.14904-17-pbonzini@redhat.com> In-Reply-To: <20231105163040.14904-1-pbonzini@redhat.com> References: <20231105163040.14904-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.6 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231105_163308_980439_156BF379 X-CRM114-Status: GOOD ( 11.87 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org From: Sean Christopherson Initialize run->exit_reason to KVM_EXIT_UNKNOWN early in KVM_RUN to reduce the probability of exiting to userspace with a stale run->exit_reason that *appears* to be valid. To support fd-based guest memory (guest memory without a corresponding userspace virtual address), KVM will exit to userspace for various memory related errors, which userspace *may* be able to resolve, instead of using e.g. BUS_MCEERR_AR. And in the more distant future, KVM will also likely utilize the same functionality to let userspace "intercept" and handle memory faults when the userspace mapping is missing, i.e. when fast gup() fails. Because many of KVM's internal APIs related to guest memory use '0' to indicate "success, continue on" and not "exit to userspace", reporting memory faults/errors to userspace will set run->exit_reason and corresponding fields in the run structure fields in conjunction with a a non-zero, negative return code, e.g. -EFAULT or -EHWPOISON. And because KVM already returns -EFAULT in many paths, there's a relatively high probability that KVM could return -EFAULT without setting run->exit_reason, in which case reporting KVM_EXIT_UNKNOWN is much better than reporting whatever exit reason happened to be in the run structure. Note, KVM must wait until after run->immediate_exit is serviced to sanitize run->exit_reason as KVM's ABI is that run->exit_reason is preserved across KVM_RUN when run->immediate_exit is true. Link: https://lore.kernel.org/all/20230908222905.1321305-1-amoorthy@google.com Link: https://lore.kernel.org/all/ZFFbwOXZ5uI%2Fgdaf@google.com Signed-off-by: Sean Christopherson Reviewed-by: Paolo Bonzini Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba Message-Id: <20231027182217.3615211-19-seanjc@google.com> Signed-off-by: Paolo Bonzini Reviewed-by: Xiaoyao Li --- arch/x86/kvm/x86.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8f9d8939b63b..f661acb01c58 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11082,6 +11082,7 @@ static int vcpu_run(struct kvm_vcpu *vcpu) { int r; + vcpu->run->exit_reason = KVM_EXIT_UNKNOWN; vcpu->arch.l1tf_flush_l1d = true; for (;;) {