From patchwork Wed Oct 14 18:26:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ben Gardon X-Patchwork-Id: 11838149 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B6CD1921 for ; Wed, 14 Oct 2020 18:28:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8D3F92222C for ; Wed, 14 Oct 2020 18:28:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="G0CBA16R" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389398AbgJNS2A (ORCPT ); Wed, 14 Oct 2020 14:28:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40224 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389409AbgJNS1q (ORCPT ); Wed, 14 Oct 2020 14:27:46 -0400 Received: from mail-qv1-xf49.google.com (mail-qv1-xf49.google.com [IPv6:2607:f8b0:4864:20::f49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A08CAC0613E2 for ; Wed, 14 Oct 2020 11:27:39 -0700 (PDT) Received: by mail-qv1-xf49.google.com with SMTP id k6so94568qvg.9 for ; Wed, 14 Oct 2020 11:27:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=89LrHzVsLlwPBCGn84hGo/p+FJBhRaw2texxmtA4jtA=; b=G0CBA16RiGAumu6zAemSqyOdhCK2t0J6mY2WbIOvQp14LFcD7co9CLm/gSj3d7ou9G XtE2cAaxSEe5Ua17Si2vIdYX7lVuMAei6cqwgXO6puYzYxn3e81DiB8pen/ANenriYWS MQ8HAiCMx2x+8+Ge7jbI98vKWUhOXzsfhAORKXZP76rjJ+BQNRXGXa4/exCXtxqUCxI+ MBcrDurIBPgrBVhTz3yzlEWtcNu1/fqxh+9osjW3AmiiPEO+J8wWZM7eZtPR65BaBhyB 0FOqWx9w2DrlrYhNfql9GH7DSU2FjrjKgWSmGLnPNMSAQPk6s+ePGXMmClf3tubOYaTl kndA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=89LrHzVsLlwPBCGn84hGo/p+FJBhRaw2texxmtA4jtA=; b=aujTsKOxLnlsKO2Vq/D5IkDHv6XAHS8u1ETnfg0OCCI+dpnkMSfsJ/ZCSfVFJlroWT /9A2RSvpnZy8EETTHkiW02u9+4W7ljIM5to/iFQoqNmGFzBCEzWGTihgGXasw+9MfqgS h0XExoNxaS7mK3Dz5jAZIrIr8YO7hbASXpgWT/3Ga0V4vOGc1etgsa75Ct+8xSA+0KsT o6QTknn3Xhx7g1K2ybzliNn988x+PzB8XRnQLhp/RdfTPl0C7eOFLbnTD6qEWSsJpO3W elgR8iz8GFHDjUFll6kqTf5uqZxtwDBzaX/IrJY6RjbK019yXr4lt61CKRjScLQXM/Nq /FsQ== X-Gm-Message-State: AOAM533Xdt42swlXdA4CeXqKxIqDnkLK5e3sikzFgtCrxbZJ55w+Dt0/ by/DfvRJdVzEXgwEHx2gESzcIwjPlnCz X-Google-Smtp-Source: ABdhPJwawAS2Dd68rKKMGCq+qgkWISOp7hkWeeEYdOms1yoISAraLw8ftyqMJBLQy+cDH0TqvBG2hrHKkY7D Sender: "bgardon via sendgmr" X-Received: from bgardon.sea.corp.google.com ([2620:15c:100:202:f693:9fff:fef4:a293]) (user=bgardon job=sendgmr) by 2002:a05:6214:2ed:: with SMTP id h13mr593520qvu.26.1602700058739; Wed, 14 Oct 2020 11:27:38 -0700 (PDT) Date: Wed, 14 Oct 2020 11:26:59 -0700 In-Reply-To: <20201014182700.2888246-1-bgardon@google.com> Message-Id: <20201014182700.2888246-20-bgardon@google.com> Mime-Version: 1.0 References: <20201014182700.2888246-1-bgardon@google.com> X-Mailer: git-send-email 2.28.0.1011.ga647a8990f-goog Subject: [PATCH v2 19/20] kvm: x86/mmu: Don't clear write flooding count for direct roots From: Ben Gardon To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Cannon Matthews , Paolo Bonzini , Peter Xu , Sean Christopherson , Peter Shier , Peter Feiner , Junaid Shahid , Jim Mattson , Yulei Zhang , Wanpeng Li , Vitaly Kuznetsov , Xiao Guangrong , Ben Gardon Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Direct roots don't have a write flooding count because the guest can't affect that paging structure. Thus there's no need to clear the write flooding count on a fast CR3 switch for direct roots. Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell machine. This series introduced no new failures. This series can be viewed in Gerrit at: https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538 Signed-off-by: Ben Gardon --- arch/x86/kvm/mmu/mmu.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 2e8bf8d19c35a..3935c10278736 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4266,7 +4266,13 @@ static void __kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd, */ vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); - __clear_sp_write_flooding_count(to_shadow_page(vcpu->arch.mmu->root_hpa)); + /* + * If this is a direct root page, it doesn't have a write flooding + * count. Otherwise, clear the write flooding count. + */ + if (!new_role.direct) + __clear_sp_write_flooding_count( + to_shadow_page(vcpu->arch.mmu->root_hpa)); } void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd, bool skip_tlb_flush,