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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED911C433F5 for ; Sat, 9 Oct 2021 02:15:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D1CAD60FD7 for ; Sat, 9 Oct 2021 02:15:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244166AbhJICR3 (ORCPT ); Fri, 8 Oct 2021 22:17:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38376 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244164AbhJICQz (ORCPT ); Fri, 8 Oct 2021 22:16:55 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C1314C06139D for ; Fri, 8 Oct 2021 19:13:46 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id i21-20020a253b15000000b005b9c0fbba45so15082821yba.20 for ; Fri, 08 Oct 2021 19:13:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=reply-to:date:in-reply-to:message-id:mime-version:references :subject:from:to:cc; bh=va765MwNV8lkPK+fPa+/nQPV7Q6ICFe76wXLuhKBR7k=; b=B5oLyIOK5DCmxdgNe+Nl5/eUZ+1dZvr28zFbfb0yUmRDrQAn6gFu0meDWGbooWcwf+ l+waGmWoLOHDfWujUlJgTIfXQBGxvJYpWrTevNrJNk5M8uz1livq3G0CbLqGnwGl0JPm sNTwBIZ8vWCCI3dUoTv7AkcFha93KYIamIUHSTRqHBmzceqRPtYmNYOCGYVyZvVn3Np/ TL6ymtR5bZm6u0h37kbtwh2/3um/F6VSleLNBRjXkJxQwQ6Tl5usknG2mBtpFmrzjKYA RfxJYCWymoaofgRtrejK3tfUhsfLqLitFSkmp9z1zLeMTRzswrj10R8lRDFv/A07PTzr ihYQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:reply-to:date:in-reply-to:message-id :mime-version:references:subject:from:to:cc; bh=va765MwNV8lkPK+fPa+/nQPV7Q6ICFe76wXLuhKBR7k=; b=tmBOexEoWG1Wrs9qDpUtOnfVYAzej0UlzH37Tmef6vCamd/h85C1RrCP0EmP8h8nmH 1dA/rGY//CtOk9CghrInOU7COUXZLlb1i5FRtDs+DPJ7nFCuQ+qmkcjZKBVOLu2/f6Ce 8p8lGDdWjmlNlLCyt2QsTHtOJPiYMxdWxMCNSV3XMwatxkdCHlaFa3mIyntRhTMyHOhO NY/LuGVT7fLbmYonPzQPL8iyjydk5lQyW6yK3SiPsfDD0R972nvpS1I08fhsAfFJ630n gIzGWOZAVUcgPkySOfwlRPYwTDq+c6ZjuF2upTMPD83sQYqqjRLXrH4AYh3qcyQIojNl hBLQ== X-Gm-Message-State: AOAM5301066ZII2f2dLwGigdCjaq2aC2OCAplySp9i0J1PJeVbl/tARm k+oEw7xXhcTx5pSek8X1aSmKfzlkmig= X-Google-Smtp-Source: ABdhPJxNwqY1vJaMvOgnvL3+QcSM5HrN4+PYEJxKTsdN858kzlppD8XZ0WLvzzYX6ErETJg0fQvQs2GFQ5w= X-Received: from seanjc798194.pdx.corp.google.com ([2620:15c:90:200:e39b:6333:b001:cb]) (user=seanjc job=sendgmr) by 2002:a25:69c7:: with SMTP id e190mr6678164ybc.334.1633745625928; Fri, 08 Oct 2021 19:13:45 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 8 Oct 2021 19:12:19 -0700 In-Reply-To: <20211009021236.4122790-1-seanjc@google.com> Message-Id: <20211009021236.4122790-27-seanjc@google.com> Mime-Version: 1.0 References: <20211009021236.4122790-1-seanjc@google.com> X-Mailer: git-send-email 2.33.0.882.g93a45727a2-goog Subject: [PATCH v2 26/43] KVM: VMX: Read Posted Interrupt "control" exactly once per loop iteration From: Sean Christopherson To: Marc Zyngier , Huacai Chen , Aleksandar Markovic , Paul Mackerras , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Paolo Bonzini Cc: James Morse , Alexandru Elisei , Suzuki K Poulose , Atish Patra , David Hildenbrand , Cornelia Huck , Claudio Imbrenda , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, David Matlack , Oliver Upton , Jing Zhang Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use READ_ONCE() when loading the posted interrupt descriptor control field to ensure "old" and "new" have the same base value. If the compiler emits separate loads, and loads into "new" before "old", KVM could theoretically drop the ON bit if it were set between the loads. Fixes: 28b835d60fcc ("KVM: Update Posted-Interrupts Descriptor when vCPU is preempted") Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/posted_intr.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c index 414ea6972b5c..fea343dcc011 100644 --- a/arch/x86/kvm/vmx/posted_intr.c +++ b/arch/x86/kvm/vmx/posted_intr.c @@ -53,7 +53,7 @@ void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu) /* The full case. */ do { - old.control = new.control = pi_desc->control; + old.control = new.control = READ_ONCE(pi_desc->control); dest = cpu_physical_id(cpu); @@ -104,7 +104,7 @@ static void __pi_post_block(struct kvm_vcpu *vcpu) "Wakeup handler not enabled while the vCPU was blocking"); do { - old.control = new.control = pi_desc->control; + old.control = new.control = READ_ONCE(pi_desc->control); dest = cpu_physical_id(vcpu->cpu); @@ -160,7 +160,7 @@ int pi_pre_block(struct kvm_vcpu *vcpu) "Posted Interrupt Suppress Notification set before blocking"); do { - old.control = new.control = pi_desc->control; + old.control = new.control = READ_ONCE(pi_desc->control); /* set 'NV' to 'wakeup vector' */ new.nv = POSTED_INTR_WAKEUP_VECTOR; -- 2.33.0.882.g93a45727a2-goog