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 9F1E0C433F5 for ; Thu, 28 Apr 2022 03:39:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242419AbiD1DnD (ORCPT ); Wed, 27 Apr 2022 23:43:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231929AbiD1DnA (ORCPT ); Wed, 27 Apr 2022 23:43:00 -0400 Received: from mail-yw1-x1135.google.com (mail-yw1-x1135.google.com [IPv6:2607:f8b0:4864:20::1135]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8AFB36FF49; Wed, 27 Apr 2022 20:39:47 -0700 (PDT) Received: by mail-yw1-x1135.google.com with SMTP id 00721157ae682-2f7c424c66cso39701947b3.1; Wed, 27 Apr 2022 20:39:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=mihABchek1Eixq9pTsDEvJD+Zdo5A9r3WorbFfIZpzE=; b=diTUXy8/eVt0YaxdFzg9kwj1y5VW3ZYyIAG1VcXLNwlNPGJISgVE10tKvWxYEWuhk2 vi1EPHKpghMO6o7uuxgxptKqbBG0EGFz1Psijc+IDqg5IkL48Ri8NSPXOvrobrKtokZx hui3skwT7H99rLlyfEunD6715gz3CiVWjxVlhNeJQcGgxyfbMe6q80utgN/ElepuTkHs R5JbVYXeknk+2GILtar3Z+2a+YVwj/6EOVlqquxwO3yXFoe9eoPV1BYHRvUZxJ3FN92A ciAImVCI51fJAeUxQO2VVn1Q/K1HwIwHU3YE1WM/UY3ts2p1zKj6UDLmRl6Nf/cNEvLT j7+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=mihABchek1Eixq9pTsDEvJD+Zdo5A9r3WorbFfIZpzE=; b=1oavkV0Mq5aSOPXB7zb1DXmpPOPQx4hZapucrLTcyjiKM/DzGAyZNDAyYplHn3qiyG j6nMqUvwVyCtwnsRj2jlpQXDth29sxcDF5MRQAEOgdm+0aiI0RCouirk/hEX53jlsLKq AH6iKbPEkcyUOipqtDzTq5mcrbrN4sLct9CdUxFmdtqa3KTIptJAaVit4tLxNfFFpVYQ 21JGp2MrDsxWrD1ELAs0bCupvEkBF86ZQAqeHh6FWQ05rISYr1swboGktGyhaMkzzsGo M9zkldUGA9LT2U4f5xbQTo1mbpPBsymz1OWvPoVkbrS1IfyAgzOvnlvDTfAooQ5n/YPv eoQg== X-Gm-Message-State: AOAM53178izP0QYXVDdmrnv7cyjP9xYvkLHnxR+n9nYRd8kpLPD24xuX oVDky2JbcikvTvMNpq2a+4On7V6/8Mi+JgTLHAs= X-Google-Smtp-Source: ABdhPJz7I6GB+kHu8lN1fpQm1FvM9jKqX1BOGg+joAovqHyJBAjwgZQ/qLAOx3Kk1/UBgKVS9VNdthzKFFV217hUiSo= X-Received: by 2002:a0d:cb41:0:b0:2f7:d205:9c99 with SMTP id n62-20020a0dcb41000000b002f7d2059c99mr22457299ywd.417.1651117186852; Wed, 27 Apr 2022 20:39:46 -0700 (PDT) MIME-Version: 1.0 References: <20220427014004.1992589-1-seanjc@google.com> <20220427014004.1992589-7-seanjc@google.com> In-Reply-To: <20220427014004.1992589-7-seanjc@google.com> From: Lai Jiangshan Date: Thu, 28 Apr 2022 11:39:35 +0800 Message-ID: Subject: Re: [PATCH v2 6/8] KVM: Fix multiple races in gfn=>pfn cache refresh To: Sean Christopherson Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, LKML , David Woodhouse , Mingwei Zhang , Maxim Levitsky Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 27, 2022 at 7:16 PM Sean Christopherson wrote: > @@ -159,10 +249,23 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, > The following code of refresh_in_progress is somewhat like mutex. + mutex_lock(&gpc->refresh_in_progress); // before write_lock_irq(&gpc->lock); Is it fit for the intention? Thanks Lai > write_lock_irq(&gpc->lock); > > + /* > + * 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. > + */ > + while (gpc->refresh_in_progress) { > + write_unlock_irq(&gpc->lock); > + > + cond_resched(); > + > + write_lock_irq(&gpc->lock); > + } > + gpc->refresh_in_progress = true; > + > old_pfn = gpc->pfn; > old_khva = gpc->khva - offset_in_page(gpc->khva); > old_uhva = gpc->uhva; > - old_valid = gpc->valid; >