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 X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D3E7DC43381 for ; Fri, 22 Mar 2019 13:04:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AD18A206BA for ; Fri, 22 Mar 2019 13:04:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731631AbfCVNEH (ORCPT ); Fri, 22 Mar 2019 09:04:07 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:42169 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730977AbfCVNEF (ORCPT ); Fri, 22 Mar 2019 09:04:05 -0400 Received: by mail-wr1-f66.google.com with SMTP id g3so2260064wrx.9 for ; Fri, 22 Mar 2019 06:04:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=dzohx9uLBVWg4NAwXMeyvzY5YQucALzki7Y15eX3710=; b=cgWVPfZcJOwGx9Q06MaqYlsD+zrSq+6OfZKnQpX0reP85NDklRmFeWxEOrACars9d0 J6+WlcLMnB1cr+PUCAfPphfmYRzuHInzu6NBL5eU0G6/l4vwZzbGhwY1PejuUU9Iv2HB 0PVDWdslmBxDSOUFiryqM+RECeuiBIzjbdF+6C/g86joKYSqt+8fehMO12XaopplrdBH OlQe9atu/v1AIO/im+YJajZFmmv27wIOP44dbjJrDqIjbjU+qL4UC1WjIacuM7CkYUv9 ZZYsr9OgURCD7VHxxzxaBHLtEeMqqnuqMDtV7nFgbaYBUGZa+yOkP5ovqXyRGDpjSAmq BXdg== X-Gm-Message-State: APjAAAVSOvidQ3CPXlvKZFx7Pw7OvlikAg3w2UQ3Xw/bVVASQApHFBR8 LavgFlnFIazq/899K8OXDhuadTTdmrM= X-Google-Smtp-Source: APXvYqw+LXGuKgpZAnsJvwpuNkIlcQhpZkFKw4Ukuhr5g3UqdujjZrrKnT6afPK2eb5E+1Kj+43BWQ== X-Received: by 2002:a5d:43c9:: with SMTP id v9mr6313895wrr.269.1553259843463; Fri, 22 Mar 2019 06:04:03 -0700 (PDT) Received: from vitty.brq.redhat.com (nat-pool-brq-t.redhat.com. [213.175.37.10]) by smtp.gmail.com with ESMTPSA id 13sm8215249wmj.33.2019.03.22.06.04.01 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 22 Mar 2019 06:04:02 -0700 (PDT) From: Vitaly Kuznetsov To: "Suthikulpanit\, Suravee" Cc: "joro\@8bytes.org" , "pbonzini\@redhat.com" , "rkrcmar\@redhat.com" , "linux-kernel\@vger.kernel.org" , "kvm\@vger.kernel.org" Subject: Re: [PATCH] svm/avic: Fix invalidate logical APIC id entry In-Reply-To: <20190322101706.9377-1-suravee.suthikulpanit@amd.com> References: <20190322101706.9377-1-suravee.suthikulpanit@amd.com> Date: Fri, 22 Mar 2019 14:04:01 +0100 Message-ID: <87ef6zcb7i.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "Suthikulpanit, Suravee" writes: > Only clear the valid bit when invalidate logical APIC id entry. > The current logic clear the valid bit, but also set the rest of > the bits (including reserved bits) to 1. > > Fixes: 98d90582be2e ('svm: Fix AVIC DFR and LDR handling') > Signed-off-by: Suravee Suthikulpanit > --- > arch/x86/kvm/svm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 7a4ce1a22ca0..f4fb766e474c 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -4640,7 +4640,7 @@ static void avic_invalidate_logical_id_entry(struct kvm_vcpu *vcpu) > u32 *entry = avic_get_logical_id_entry(vcpu, svm->ldr_reg, flat); > > if (entry) > - WRITE_ONCE(*entry, (u32) ~AVIC_LOGICAL_ID_ENTRY_VALID_MASK); > + WRITE_ONCE(*entry, (u32)(*entry & ~AVIC_LOGICAL_ID_ENTRY_VALID_MASK)); I'm not sure how important this is, but this change creates a tiny time window between reading from *entry and writing there. Should we use atomic bitops instead? > } > > static int avic_handle_ldr_update(struct kvm_vcpu *vcpu) -- Vitaly