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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C1302EE0213 for ; Thu, 14 Sep 2023 03:17:43 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=T/RmXvPb; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4RmMvV2ytfz3dHv for ; Thu, 14 Sep 2023 13:17:42 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=T/RmXvPb; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=linux.intel.com (client-ip=134.134.136.65; helo=mgamail.intel.com; envelope-from=binbin.wu@linux.intel.com; receiver=lists.ozlabs.org) Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4RmMgk09gvz3dFn for ; Thu, 14 Sep 2023 13:07:27 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1694660850; x=1726196850; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=hQLGmdNELjYMZnPnnmaVF9DnSi0UkgWqzZbEZVq1o/k=; b=T/RmXvPb3T9yQJqfVRcPAswmgau3k4FfgNnkMQfb8xKLF2QroAPFsVP5 zmtEqkp5cerWUQCa4wPXjVakPtttnYCC5oLoh4Eh5iRIxI0BCAwKiCzwk M7ccTrB4o5BFn8CrGzllp3bdVX+8CsidoAE3uTconmG4rgk1I5v4BRPE6 MNiuW6CHzgag0SrZFnvCNWh8Far9jVg6MQi0N6obfVOUuWtQxvopYs8BS xWcwGo1iIpap/4Xg7oQL/JsvdtC48UB3JbqSeQ9+Ek4M+nlQ8PnEVDdkI Phj564WejTY4fMAY2WmRshltvxAoukfgIHSlNRu/+tVCDXH9OpHeI0ECp A==; X-IronPort-AV: E=McAfee;i="6600,9927,10832"; a="382644873" X-IronPort-AV: E=Sophos;i="6.02,144,1688454000"; d="scan'208";a="382644873" 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 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 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, David Hildenbrand , Yu Zhang , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, Isaku Yamahata , Paul Moore , Marc Zyngier , Huacai Chen , James Morris , "Matthew Wilcox \(Oracle\)" , Wang , Fuad Tabba , Jarkko Sakkinen , "Serge E. Hallyn" , Maciej Szmigiero , Albert Ou , Vlastimil Babka , Michael Roth , Ackerley Tng , Paul Walmsley , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, Isaku Yamahata , Quentin Perret , Liam Merwick , linux-mips@vger.kernel.org, Oliv er Upton , linux-security-module@vger.kernel.org, Palmer Dabbelt , "Kirill A . Shutemov" , kvm-riscv@lists.infradead.org, Anup Patel , linux-fsdevel@vger.kernel.org, Paolo Bonzini , Andrew Morton , Vishal Annapurve , linuxppc-dev@lists.ozlabs.org, Xu Yilun , Anish Moorthy Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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,