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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75CBCC433EF for ; Thu, 18 Nov 2021 17:44:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5CCE661131 for ; Thu, 18 Nov 2021 17:44:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234188AbhKRRq7 (ORCPT ); Thu, 18 Nov 2021 12:46:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234168AbhKRRq6 (ORCPT ); Thu, 18 Nov 2021 12:46:58 -0500 Received: from mail-io1-xd2a.google.com (mail-io1-xd2a.google.com [IPv6:2607:f8b0:4864:20::d2a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 551CDC061574 for ; Thu, 18 Nov 2021 09:43:58 -0800 (PST) Received: by mail-io1-xd2a.google.com with SMTP id v23so9055628iom.12 for ; Thu, 18 Nov 2021 09:43:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=YmWc7qIUDoaNMJwYkB1mdPXNq1GKCmwNkveJmjIq/nI=; b=R0F7nl6l02m98nslLgBmwCrZbMadQE6rGz5kKt+GSzDqAjDbH1NR4MMxMnKMuK7TzF HsWapVtmX4NXV8aL/tIDI6hbpht0fU+iGVI7d0+QR6bI/YCM9yVpETXtZKQBM6uCgRGA xIbj7wkqx4uy1kUvWPoIRKNPYq1oWwsKk5XKKxKyAufAaXU9RMCtIRiM7HQVmnmWCMWT jegAAW2bQe4NA6WoLcJ5fJRuFvzIAKofMwr4z9pq1eNToWiZy/Ov+AZfAY4Ja+p6pAR1 d7F32BpCo9J4iMoAVideuD2tdb7xytbsEiUBG5zsS3UHkIYBNd0YVta/GhxH24XCrbd2 Sj8A== 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=YmWc7qIUDoaNMJwYkB1mdPXNq1GKCmwNkveJmjIq/nI=; b=ozaOzwPQOOYNrUhHECwW6RZeWWth3xrm5s+SIV5LeFplWVBbyH790CPMgv4OyKDUGb jmsKR8eEmmiJDwSDHf9xUu+CqQAo95DG5nvQnvdoq847vprTUa4SKkoF8h2ltDfXjXr4 tsLaguEIlQRZDOvrQYgHk9dmhOegQtoETS2ld1GTJH0YoptLuO+oWLoHA6t4hGkKpOAe s3UXgHEyKBBPrCMQO1DT6//uhucBMw40r9mxi/+hfpqVvF4o9DgKDtNrrYvAftSfgV0E krvLnCJ4NmEvJlYx1mXnWufUIU4kCyVJrwhuf5yN/WBuRXD6wb0uXp1/uqdYYGffl7yN 4hGg== X-Gm-Message-State: AOAM531MV1SYd/HyXlrQn9HfcBO5RRd7ACs28BQRxrXniV8JLEZ8H7X0 7o6enTW/sjn5SVOmO7KcRrwGD45QwM+k4vuFCIFhOw== X-Google-Smtp-Source: ABdhPJy/ex0GEDw34YUwbvewezGGWyJ3Vmks3SCJirwTDPEeVKLHZg8u7glXzPmhRI7m6CtbmqoZ9NM9idVx+dJ5frQ= X-Received: by 2002:a5d:8049:: with SMTP id b9mr620384ior.41.1637257437596; Thu, 18 Nov 2021 09:43:57 -0800 (PST) MIME-Version: 1.0 References: <20211110223010.1392399-1-bgardon@google.com> <20211110223010.1392399-8-bgardon@google.com> In-Reply-To: From: Ben Gardon Date: Thu, 18 Nov 2021 09:43:46 -0800 Message-ID: Subject: Re: [RFC 07/19] KVM: x86/mmu: Factor wrprot for nested PML out of make_spte To: Sean Christopherson Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Paolo Bonzini , Peter Xu , Peter Shier , David Matlack , Mingwei Zhang , Yulei Zhang , Wanpeng Li , Xiao Guangrong , Kai Huang , Keqian Zhu , David Hildenbrand Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 17, 2021 at 6:12 PM Sean Christopherson wrote: > > On Wed, Nov 10, 2021, Ben Gardon wrote: > > When running a nested VM, KVM write protects SPTEs in the EPT/NPT02 > > instead of using PML for dirty tracking. This avoids expensive > > translation later, when emptying the Page Modification Log. In service > > of removing the vCPU pointer from make_spte, factor the check for nested > > PML out of the function. > > Aha! The dependency on @vcpu can be avoided without having to take a flag from > the caller. The shadow page has everything we need. The check is really "is this > a page for L2 EPT". The kvm_x86_ops.cpu_dirty_log_size gets us the EPT part, and > kvm_mmu_page.guest_mode gets us the L2 part. Haha that's way cleaner than what I was doing! Seems like an obvious solution in retrospect. I'll include this in the next version of the series I send out unless Paolo beats me and just merges it directly. Happy to give this my reviewed-by. > > Compile tested only... > > From 773414e4fd7010c38ac89221d16089f3dcc57467 Mon Sep 17 00:00:00 2001 > From: Sean Christopherson > Date: Wed, 17 Nov 2021 18:08:42 -0800 > Subject: [PATCH] KVM: x86/mmu: Use shadow page role to detect PML-unfriendly > pages for L2 > > Rework make_spte() to query the shadow page's role, specifically whether > or not it's a guest_mode page, a.k.a. a page for L2, when determining if > the SPTE is compatible with PML. This eliminates a dependency on @vcpu, > with a future goal of being able to create SPTEs without a specific vCPU. > > Signed-off-by: Sean Christopherson Reviewed-by: Ben Gardon > --- > arch/x86/kvm/mmu/mmu_internal.h | 7 +++---- > arch/x86/kvm/mmu/spte.c | 2 +- > 2 files changed, 4 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h > index 8ede43a826af..03882b2624c8 100644 > --- a/arch/x86/kvm/mmu/mmu_internal.h > +++ b/arch/x86/kvm/mmu/mmu_internal.h > @@ -109,7 +109,7 @@ static inline int kvm_mmu_page_as_id(struct kvm_mmu_page *sp) > return kvm_mmu_role_as_id(sp->role); > } > > -static inline bool kvm_vcpu_ad_need_write_protect(struct kvm_vcpu *vcpu) > +static inline bool kvm_mmu_page_ad_need_write_protect(struct kvm_mmu_page *sp) > { > /* > * When using the EPT page-modification log, the GPAs in the CPU dirty > @@ -117,10 +117,9 @@ static inline bool kvm_vcpu_ad_need_write_protect(struct kvm_vcpu *vcpu) > * on write protection to record dirty pages, which bypasses PML, since > * writes now result in a vmexit. Note, the check on CPU dirty logging > * being enabled is mandatory as the bits used to denote WP-only SPTEs > - * are reserved for NPT w/ PAE (32-bit KVM). > + * are reserved for PAE paging (32-bit KVM). > */ > - return vcpu->arch.mmu == &vcpu->arch.guest_mmu && > - kvm_x86_ops.cpu_dirty_log_size; > + return kvm_x86_ops.cpu_dirty_log_size && sp->role.guest_mode; > } > > int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, > diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c > index 0c76c45fdb68..84e64dbdd89e 100644 > --- a/arch/x86/kvm/mmu/spte.c > +++ b/arch/x86/kvm/mmu/spte.c > @@ -101,7 +101,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, > > if (sp->role.ad_disabled) > spte |= SPTE_TDP_AD_DISABLED_MASK; > - else if (kvm_vcpu_ad_need_write_protect(vcpu)) > + else if (kvm_mmu_page_ad_need_write_protect(sp)) > spte |= SPTE_TDP_AD_WRPROT_ONLY_MASK; > > /* > --