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=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 472BAC433B4 for ; Fri, 23 Apr 2021 08:13:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 13CE76128A for ; Fri, 23 Apr 2021 08:13:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241428AbhDWINt (ORCPT ); Fri, 23 Apr 2021 04:13:49 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:46488 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241361AbhDWINr (ORCPT ); Fri, 23 Apr 2021 04:13:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619165590; 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=JV8lxB5jxKaMLebE0kj34sple4uhf5PyGZQen4ktIWM=; b=LDz91TX5E08jq4PvBHjAAmeNhVuzOJpP2I+AlgYMgcXhJP5ychacd+buwwUkA1q9y/DIHn elV3qE9Z+WqQwod+eNb56F32CtxMzlFEixaW0qY8vN/jCMG1Tc+l5EeSw7x+B5T6wPbBrV m7GXp92o5N0zw74YkH+H1xesbOZ3snw= Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-244-X8GxsUdhMfehJZ0A0CoyAA-1; Fri, 23 Apr 2021 04:13:09 -0400 X-MC-Unique: X8GxsUdhMfehJZ0A0CoyAA-1 Received: by mail-ed1-f69.google.com with SMTP id f1-20020a0564021941b02903850806bb32so12263003edz.9 for ; Fri, 23 Apr 2021 01:13:08 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=JV8lxB5jxKaMLebE0kj34sple4uhf5PyGZQen4ktIWM=; b=RdIH6CUhcNRzmlM4lbksCbdgmzoh2UgdLpwXqrggdEzKuicnsqxwEMYaeRm721yWu0 0jyQ/JYxqcuhAvSD0cBjLh97hVKPecKwt7qIvvrwTuBHNnpWKON3zWRnBPyx2fvhAcWO LFG67onjmdEQ/ODq4RLQ8QVYI7gqkq0Woep1oUAJUTGuWs8lJHSPqT6JmCrIawJqxyB4 JsPWe/NPQAuQvKhMPtoeY7Xo5h021SxIEU0i7C4PBB8XZTdpEqIoQvZwXh4ud4as18qb exmxorrjf8Zi+1Fed+tdpe/iZk+vU98Bj4gWEMle+YOmLQcFzVtDtpBBw0IXC91dQajc U4ug== X-Gm-Message-State: AOAM531u9pE9CWa/N/wQLD88yhA9Hl1Gu1Cvrk5AONS7isbzaMLauDcj HCSUwLv8YjVrfT8CUK4oJ6lUmkdEB0KBcKrOXB3XHivSDMFuXSUCsvBMlOlfRhi0QW/YhRhYoib a+VRAhQ8OhhhsEHj9na0ovL5d X-Received: by 2002:a17:906:80d1:: with SMTP id a17mr2940524ejx.55.1619165587543; Fri, 23 Apr 2021 01:13:07 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwmHJI1X+H7hKlvBNxRQOwhvUiNXWScEBXZM+Kc2dHSs2YT40KOzysDXFu7gbrM6y/ENjHjaw== X-Received: by 2002:a17:906:80d1:: with SMTP id a17mr2940509ejx.55.1619165587397; Fri, 23 Apr 2021 01:13:07 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id f19sm3521662ejc.54.2021.04.23.01.13.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 23 Apr 2021 01:13:06 -0700 (PDT) Subject: Re: [PATCH] KVM: x86/xen: Take srcu lock when accessing kvm_memslots() To: Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel References: <1619161883-5963-1-git-send-email-wanpengli@tencent.com> From: Paolo Bonzini Message-ID: Date: Fri, 23 Apr 2021 10:13:05 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <1619161883-5963-1-git-send-email-wanpengli@tencent.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23/04/21 09:11, Wanpeng Li wrote: > From: Wanpeng Li > > kvm_memslots() will be called by kvm_write_guest_offset_cached() so > take the srcu lock. > > Signed-off-by: Wanpeng Li Good catch. But I would pull it from kvm_steal_time_set_preempted to kvm_arch_vcpu_put instead. Paolo > --- > arch/x86/kvm/xen.c | 18 ++++++++++++++---- > 1 file changed, 14 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c > index ae17250..d0df782 100644 > --- a/arch/x86/kvm/xen.c > +++ b/arch/x86/kvm/xen.c > @@ -96,6 +96,7 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) > struct kvm_vcpu_xen *vx = &v->arch.xen; > uint64_t state_entry_time; > unsigned int offset; > + int idx; > > kvm_xen_update_runstate(v, state); > > @@ -133,10 +134,16 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) > BUILD_BUG_ON(sizeof(((struct compat_vcpu_runstate_info *)0)->state_entry_time) != > sizeof(state_entry_time)); > > + /* > + * Take the srcu lock as memslots will be accessed to check the gfn > + * cache generation against the memslots generation. > + */ > + idx = srcu_read_lock(&v->kvm->srcu); > + > if (kvm_write_guest_offset_cached(v->kvm, &v->arch.xen.runstate_cache, > &state_entry_time, offset, > sizeof(state_entry_time))) > - return; > + goto out; > smp_wmb(); > > /* > @@ -154,7 +161,7 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) > &vx->current_runstate, > offsetof(struct vcpu_runstate_info, state), > sizeof(vx->current_runstate))) > - return; > + goto out; > > /* > * Write the actual runstate times immediately after the > @@ -173,7 +180,7 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) > &vx->runstate_times[0], > offset + sizeof(u64), > sizeof(vx->runstate_times))) > - return; > + goto out; > > smp_wmb(); > > @@ -186,7 +193,10 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) > if (kvm_write_guest_offset_cached(v->kvm, &v->arch.xen.runstate_cache, > &state_entry_time, offset, > sizeof(state_entry_time))) > - return; > + goto out; > + > +out: > + srcu_read_unlock(&v->kvm->srcu, idx); > } > > int __kvm_xen_has_interrupt(struct kvm_vcpu *v) >