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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA542C433EF for ; Fri, 20 May 2022 15:25:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350825AbiETPZV (ORCPT ); Fri, 20 May 2022 11:25:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350813AbiETPY7 (ORCPT ); Fri, 20 May 2022 11:24:59 -0400 Received: from mail-ej1-x62c.google.com (mail-ej1-x62c.google.com [IPv6:2a00:1450:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 601041790B2; Fri, 20 May 2022 08:24:56 -0700 (PDT) Received: by mail-ej1-x62c.google.com with SMTP id jx22so2789639ejb.12; Fri, 20 May 2022 08:24:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=YELfX0pmeRUgrcCLL0vitmfjUp+FF2g5+k5k9fNku9Y=; b=pKR31M0v6C/YLf4xLrR/H2QGjVd5fR7zibIY7qMC7AxbzZUl02O+jEagoEsrP1OvYY U1ELKH8KmnXSOLc3zivWXuyW3h4xIvGD+6TYrS4zEHglmBz1E3MzfaGKFKqjb/0yKZd3 8vlgaohBPH+/6epiKmYQynin1DPIAsuV1CDY7Id3hjAUGAu4HYQOtBC03sbXe6V7Winm 5Q6uTatnhOjWjktyKdGMFt90zH1mq56n5/teSOHK2C2dXQjcRFtger6iUnky7GQEkK0P usM1DIPiRi8kSvMCpBPWlc5Dy2fjgHVkJjOHfIysA3N5UIt9xG+xrJADm/syXTI4tNB4 j5xA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:message-id:date:mime-version:user-agent :subject:content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=YELfX0pmeRUgrcCLL0vitmfjUp+FF2g5+k5k9fNku9Y=; b=lPTW4Vljpfm5WEBuoGmwcWI0MSYoIkBhh2oPalYh6E2dVxBYbyOThCE4FISdCB2i+t 607srHr5z/5AjHriMcQ7HhJNiKgoj0FR3TgPnHiWX3Cr8nRvgxtpJgW9O7tY3n3tfMEz aHp0E8KqIJZyC30o8GxEcPFpK84bz+fGviCxYd2qV0jve1LLeT1j4iprVsgS4cZn1UbD 7U/xK/I7ehBaONMe/OkFNS4Rex4aE27EXVBCf1R3FDoMicYZu0vQipv8kXLJMcA8Bm6Y QmZe8NX2TahI2ZSE82U+ghogwPbrgGVmaM2JwnF24zt54T8RbeFdNR8c9tQ/WywMQAeE BPLA== X-Gm-Message-State: AOAM533qIQc3DN52h05k6PAhEc3a+ZihZZzaw8Mp/8+CfkMnMoaWvSg8 +f7OYc3Mu6JxVBVOMOVbQtKTL8pKKMDKaQ== X-Google-Smtp-Source: ABdhPJzFUg9+Nw69pvwrhOYP4aLoaeB6c3kLan/f7n6vyz0QQZqAxtBXlGmxunn6uOcH9Df/Ci0gzQ== X-Received: by 2002:a17:907:7e91:b0:6f4:3b93:1f6e with SMTP id qb17-20020a1709077e9100b006f43b931f6emr4434383ejc.91.1653060294829; Fri, 20 May 2022 08:24:54 -0700 (PDT) Received: from ?IPV6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.googlemail.com with ESMTPSA id md17-20020a170906ae9100b006feaf472637sm759468ejb.53.2022.05.20.08.24.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 20 May 2022 08:24:54 -0700 (PDT) Sender: Paolo Bonzini Message-ID: Date: Fri, 20 May 2022 17:24:51 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH v3 6/8] KVM: Fully serialize gfn=>pfn cache refresh via mutex Content-Language: en-US To: Sean Christopherson Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Lai Jiangshan , David Woodhouse , Mingwei Zhang References: <20220429210025.3293691-1-seanjc@google.com> <20220429210025.3293691-7-seanjc@google.com> From: Paolo Bonzini In-Reply-To: <20220429210025.3293691-7-seanjc@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/29/22 23:00, Sean Christopherson wrote: > diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c > index 05cb0bcbf662..eaef31462bbe 100644 > --- a/virt/kvm/pfncache.c > +++ b/virt/kvm/pfncache.c > @@ -157,6 +157,13 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, > if (page_offset + len > PAGE_SIZE) > return -EINVAL; > > + /* > + * If another task is refreshing the cache, wait for it to complete. > + * There is no guarantee that concurrent refreshes will see the same > + * gpa, memslots generation, etc..., so they must be fully serialized. > + */ > + mutex_lock(&gpc->refresh_lock); > + > write_lock_irq(&gpc->lock); > > old_pfn = gpc->pfn; > @@ -248,6 +255,8 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, > out: > write_unlock_irq(&gpc->lock); > > + mutex_unlock(&gpc->refresh_lock); > + > gpc_release_pfn_and_khva(kvm, old_pfn, old_khva); > > return ret; Does kvm_gfn_to_pfn_cache_unmap also need to take the mutex, to avoid the WARN_ON(gpc->valid)? Paolo