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 B5CAAE7AD77 for ; Tue, 3 Oct 2023 16:56:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240654AbjJCQ4K (ORCPT ); Tue, 3 Oct 2023 12:56:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56048 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240687AbjJCQ4B (ORCPT ); Tue, 3 Oct 2023 12:56:01 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB907C6 for ; Tue, 3 Oct 2023 09:55:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1696352109; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UKz6JlccCVdwAjHFNSIJ5aqOB7SHuX73H5DKrk7P0eA=; b=NV3xFTQqMwgD8KpiFHYzwYJr6yQD76cozrANOUZiW8o04MHxXt56oOihx/QASM0vfLUSAo hT+rV/hS3ibUL7PDLvj4G0pL23m9amLeAEV1iqJNBawnnm3cU4mSBxO69pAJEtXnAU4F87 VI4k8mKxgLTT/mmcZRcy4XBn7Ijb6nc= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-424-gVIMYK-1O5-c0FIvQaxWPg-1; Tue, 03 Oct 2023 12:54:52 -0400 X-MC-Unique: gVIMYK-1O5-c0FIvQaxWPg-1 Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-3fe1521678fso9378915e9.1 for ; Tue, 03 Oct 2023 09:54:52 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696352091; x=1696956891; h=content-transfer-encoding:mime-version:user-agent:references :in-reply-to:date:cc:to:from:subject:message-id:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=UKz6JlccCVdwAjHFNSIJ5aqOB7SHuX73H5DKrk7P0eA=; b=dPKiCPk4e5LWy0+MMDglfdGkI8XPVzbI18z11boGkEgoQpyqQSIJL7FUXKMuZA+z2K 5wY4ayTbB+PqfJq8QsyZpLI49bij/8bCm2I7dg2K51fDW5juDM74h87TF3J1V6utcnNG lXysZsfINn2TbH2820LMt9g5J5/xr5/45Ngb8JKgM9X0IYJapEYVzxrTYx1AvVl6MpKf ede5Ll8OwY1i9l2aBAvvP14PQ9lM/xzjRx4VXugmbNRT07bjuq0IMP3Ia8aAeNqWkWsQ LVJxpPwXuuncpJYYXVVFM5J9kesktiXraeUw/jrvbcJXh6CiquRXuGNubcmhZoyKuWI0 gkwQ== X-Gm-Message-State: AOJu0YzoButjeT3RrYcFARi27VlRD5z2ZPIxt7SeOJddGD6a8PHd8nET Q6ctd57NYWNh3vuYzEg3HL1hUlktkBJP4Ol4GR+lawf6no3C+pP18J6jSYeBy81leCK62KSGa2m oEW42kneI2l3rdvHQlzajCL7j X-Received: by 2002:a5d:46cc:0:b0:31f:8999:c409 with SMTP id g12-20020a5d46cc000000b0031f8999c409mr12798724wrs.66.1696352091205; Tue, 03 Oct 2023 09:54:51 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHEw8GrseodyMNQjRvXwM2R7y7QiATyOCHeguCOnxlPwguiOvboAnAcudNz+gmFlWejG4+qew== X-Received: by 2002:a5d:46cc:0:b0:31f:8999:c409 with SMTP id g12-20020a5d46cc000000b0031f8999c409mr12798708wrs.66.1696352090912; Tue, 03 Oct 2023 09:54:50 -0700 (PDT) Received: from starship ([89.237.100.246]) by smtp.gmail.com with ESMTPSA id c6-20020a5d4cc6000000b00325c7295450sm1977795wrt.3.2023.10.03.09.54.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Oct 2023 09:54:50 -0700 (PDT) Message-ID: Subject: Re: [PATCH v9 5/6] KVM: x86: Migrate to __kvm_follow_pfn From: Maxim Levitsky To: David Stevens , Sean Christopherson Cc: Yu Zhang , Isaku Yamahata , Zhi Wang , kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Date: Tue, 03 Oct 2023 19:54:48 +0300 In-Reply-To: <20230911021637.1941096-6-stevensd@google.com> References: <20230911021637.1941096-1-stevensd@google.com> <20230911021637.1941096-6-stevensd@google.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org У пн, 2023-09-11 у 11:16 +0900, David Stevens пише: > From: David Stevens > > Migrate functions which need access to is_refcounted_page to > __kvm_follow_pfn. The functions which need this are __kvm_faultin_pfn > and reexecute_instruction. The former requires replacing the async > in/out parameter with FOLL_NOWAIT parameter and the KVM_PFN_ERR_NEEDS_IO > return value. Handling non-refcounted pages is complicated, so it will > be done in a followup. The latter is a straightforward refactor. > > APIC related callers do not need to migrate because KVM controls the > memslot, so it will always be regular memory. Prefetch related callers > do not need to be migrated because atomic gfn_to_pfn calls can never > make it to hva_to_pfn_remapped. > > Signed-off-by: David Stevens > --- > arch/x86/kvm/mmu/mmu.c | 43 ++++++++++++++++++++++++++++++++---------- > arch/x86/kvm/x86.c | 12 ++++++++++-- > 2 files changed, 43 insertions(+), 12 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index e1d011c67cc6..e1eca26215e2 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -4254,7 +4254,14 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) > static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) > { > struct kvm_memory_slot *slot = fault->slot; > - bool async; > + struct kvm_follow_pfn foll = { > + .slot = slot, > + .gfn = fault->gfn, > + .flags = fault->write ? FOLL_WRITE : 0, > + .try_map_writable = true, > + .guarded_by_mmu_notifier = true, > + .allow_non_refcounted_struct_page = false, > + }; > > /* > * Retry the page fault if the gfn hit a memslot that is being deleted > @@ -4283,12 +4290,20 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > return RET_PF_EMULATE; > } > > - async = false; > - fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, false, &async, > - fault->write, &fault->map_writable, > - &fault->hva); > - if (!async) > - return RET_PF_CONTINUE; /* *pfn has correct page already */ > + foll.flags |= FOLL_NOWAIT; > + fault->pfn = __kvm_follow_pfn(&foll); > + > + if (!is_error_noslot_pfn(fault->pfn)) > + goto success; Unrelated but I can't say I like the 'is_error_noslot_pfn()' name, I wish it was called something like is_valid_pfn(). > + > + /* > + * If __kvm_follow_pfn() failed because I/O is needed to fault in the > + * page, then either set up an asynchronous #PF to do the I/O, or if > + * doing an async #PF isn't possible, retry __kvm_follow_pfn() with > + * I/O allowed. All other failures are fatal, i.e. retrying won't help. > + */ > + if (fault->pfn != KVM_PFN_ERR_NEEDS_IO) > + return RET_PF_CONTINUE; > > if (!fault->prefetch && kvm_can_do_async_pf(vcpu)) { > trace_kvm_try_async_get_page(fault->addr, fault->gfn); > @@ -4306,9 +4321,17 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > * to wait for IO. Note, gup always bails if it is unable to quickly > * get a page and a fatal signal, i.e. SIGKILL, is pending. > */ > - fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, true, NULL, > - fault->write, &fault->map_writable, > - &fault->hva); > + foll.flags |= FOLL_INTERRUPTIBLE; > + foll.flags &= ~FOLL_NOWAIT; > + fault->pfn = __kvm_follow_pfn(&foll); > + > + if (!is_error_noslot_pfn(fault->pfn)) > + goto success; > + > + return RET_PF_CONTINUE; > +success: > + fault->hva = foll.hva; > + fault->map_writable = foll.writable; > return RET_PF_CONTINUE; > } > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 6c9c81e82e65..2011a7e47296 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -8556,6 +8556,7 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, > { > gpa_t gpa = cr2_or_gpa; > kvm_pfn_t pfn; > + struct kvm_follow_pfn foll; > > if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF)) > return false; > @@ -8585,7 +8586,13 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, > * retry instruction -> write #PF -> emulation fail -> retry > * instruction -> ... > */ > - pfn = gfn_to_pfn(vcpu->kvm, gpa_to_gfn(gpa)); > + foll = (struct kvm_follow_pfn) { > + .slot = gfn_to_memslot(vcpu->kvm, gpa_to_gfn(gpa)), > + .gfn = gpa_to_gfn(gpa), > + .flags = FOLL_WRITE, > + .allow_non_refcounted_struct_page = true, > + }; > + pfn = __kvm_follow_pfn(&foll); > > /* > * If the instruction failed on the error pfn, it can not be fixed, > @@ -8594,7 +8601,8 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, > if (is_error_noslot_pfn(pfn)) > return false; > > - kvm_release_pfn_clean(pfn); > + if (foll.is_refcounted_page) > + kvm_release_page_clean(pfn_to_page(pfn)); > > /* The instructions are well-emulated on direct mmu. */ > if (vcpu->arch.mmu->root_role.direct) { Overall looks good, I might have missed something. Reviewed-by: Maxim Levitsky Best regards, Maxim Levitsky