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 906CAEE021E for ; Thu, 14 Sep 2023 03:07:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234244AbjINDHf (ORCPT ); Wed, 13 Sep 2023 23:07:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58456 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234231AbjINDH2 (ORCPT ); Wed, 13 Sep 2023 23:07:28 -0400 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EB7351BD3; Wed, 13 Sep 2023 20:07:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1694660844; x=1726196844; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=hQLGmdNELjYMZnPnnmaVF9DnSi0UkgWqzZbEZVq1o/k=; b=FI9x9MO5qnIqKzGBysp95vNBROi36Q7/V4jPiHVcgspt8vmNYz8klgfq 3CZCTuGPniIWfha733s4sET13N09B2ekEYh+sY4awVSxC94jcck6ZUU0o S9d4kORNFCh6bcMBDei7xLcde4JADeQgnnUsS1e54AGIKaa5vuTDHEt2L 3fH2BsYqqbttb3R7bJSv8KXbXXfYf/tQJhhzyhvMCrYlRxmskLtX0y4qo H0sIU19QQE5d6TU2NQQZ6aZzan5ZAO9tvN5SuMqZDk5oEKjKMEXbyuE5u bfYod9APQN2sBs4JcveKa0dTedprBke5YUFwLSIwO4LJ+YFABiOKtdTuL g==; X-IronPort-AV: E=McAfee;i="6600,9927,10832"; a="382644882" X-IronPort-AV: E=Sophos;i="6.02,144,1688454000"; d="scan'208";a="382644882" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Sep 2023 20:07:23 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10832"; a="747565104" X-IronPort-AV: E=Sophos;i="6.02,144,1688454000"; d="scan'208";a="747565104" Received: from binbinwu-mobl.ccr.corp.intel.com (HELO [10.238.8.84]) ([10.238.8.84]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Sep 2023 20:07:14 -0700 Message-ID: <54d3e6bf-d374-caa5-0920-bb2fe3b7595c@linux.intel.com> Date: Thu, 14 Sep 2023 11:07:12 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [RFC PATCH v12 02/33] KVM: Use gfn instead of hva for mmu_notifier_retry To: Sean Christopherson , Chao Peng Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Paolo Bonzini , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , "Matthew Wilcox (Oracle)" , Andrew Morton , Paul Moore , James Morris , "Serge E. Hallyn" , Fuad Tabba , Jarkko Sakkinen , Anish Moorthy , Yu Zhang , Isaku Yamahata , Xu Yilun , Vlastimil Babka , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" References: <20230914015531.1419405-1-seanjc@google.com> <20230914015531.1419405-3-seanjc@google.com> From: Binbin Wu In-Reply-To: <20230914015531.1419405-3-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 9/14/2023 9:55 AM, Sean Christopherson wrote: > From: Chao Peng > > Currently in mmu_notifier invalidate path, hva range is recorded and > then checked against by mmu_notifier_retry_hva() in the page fault > handling path. However, for the to be introduced private memory, a page > fault may not have a hva associated, checking gfn(gpa) makes more sense. > > For existing hva based shared memory, gfn is expected to also work. The > only downside is when aliasing multiple gfns to a single hva, the > current algorithm of checking multiple ranges could result in a much > larger range being rejected. Such aliasing should be uncommon, so the > impact is expected small. > > Suggested-by: Sean Christopherson > Signed-off-by: Chao Peng > Reviewed-by: Fuad Tabba > Tested-by: Fuad Tabba > [sean: convert vmx_set_apic_access_page_addr() to gfn-based API] > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/mmu/mmu.c | 10 ++++++---- > arch/x86/kvm/vmx/vmx.c | 11 +++++------ > include/linux/kvm_host.h | 33 +++++++++++++++++++++------------ > virt/kvm/kvm_main.c | 40 +++++++++++++++++++++++++++++++--------- > 4 files changed, 63 insertions(+), 31 deletions(-) > [...] > > -void kvm_mmu_invalidate_begin(struct kvm *kvm, unsigned long start, > - unsigned long end) > +void kvm_mmu_invalidate_begin(struct kvm *kvm) > { > + lockdep_assert_held_write(&kvm->mmu_lock); > /* > * The count increase must become visible at unlock time as no > * spte can be established without taking the mmu_lock and > * count is also read inside the mmu_lock critical section. > */ > kvm->mmu_invalidate_in_progress++; > + > + if (likely(kvm->mmu_invalidate_in_progress == 1)) > + kvm->mmu_invalidate_range_start = INVALID_GPA; > +} > + > +void kvm_mmu_invalidate_range_add(struct kvm *kvm, gfn_t start, gfn_t end) > +{ > + lockdep_assert_held_write(&kvm->mmu_lock); > + > + WARN_ON_ONCE(!kvm->mmu_invalidate_in_progress); > + > if (likely(kvm->mmu_invalidate_in_progress == 1)) { > kvm->mmu_invalidate_range_start = start; > kvm->mmu_invalidate_range_end = end; > @@ -771,6 +781,12 @@ void kvm_mmu_invalidate_begin(struct kvm *kvm, unsigned long start, > } > } > > +static bool kvm_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) > +{ > + kvm_mmu_invalidate_range_add(kvm, range->start, range->end); > + return kvm_unmap_gfn_range(kvm, range); > +} > + > static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, > const struct mmu_notifier_range *range) > { > @@ -778,7 +794,7 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, > const struct kvm_mmu_notifier_range hva_range = { > .start = range->start, > .end = range->end, > - .handler = kvm_unmap_gfn_range, > + .handler = kvm_mmu_unmap_gfn_range, > .on_lock = kvm_mmu_invalidate_begin, > .on_unlock = kvm_arch_guest_memory_reclaimed, > .flush_on_ret = true, > @@ -817,8 +833,7 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, > return 0; > } > > -void kvm_mmu_invalidate_end(struct kvm *kvm, unsigned long start, > - unsigned long end) > +void kvm_mmu_invalidate_end(struct kvm *kvm) > { > /* > * This sequence increase will notify the kvm page fault that > @@ -833,6 +848,13 @@ void kvm_mmu_invalidate_end(struct kvm *kvm, unsigned long start, > * in conjunction with the smp_rmb in mmu_invalidate_retry(). > */ > kvm->mmu_invalidate_in_progress--; > + > + /* > + * Assert that at least one range must be added between start() and > + * end(). Not adding a range isn't fatal, but it is a KVM bug. > + */ > + WARN_ON_ONCE(kvm->mmu_invalidate_in_progress && > + kvm->mmu_invalidate_range_start == INVALID_GPA); Should the check happen before the decrease of kvm->mmu_invalidate_in_progress? Otherwise, KVM calls kvm_mmu_invalidate_begin(), then kvm_mmu_invalidate_end() the check will not take effect. > } > > static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn,