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[2620:137:e000::1:20]) by mx.google.com with ESMTP id h13-20020a05640250cd00b004616acd9cbcsi771183edb.360.2022.12.08.22.06.32; Thu, 08 Dec 2022 22:06:51 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b=gfFjkSIK; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229634AbiLIFpf (ORCPT + 73 others); Fri, 9 Dec 2022 00:45:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33004 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229564AbiLIFpb (ORCPT ); Fri, 9 Dec 2022 00:45:31 -0500 Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B088A1FCE9; Thu, 8 Dec 2022 21:45:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1670564729; x=1702100729; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=bZyUarVu5cC9rT3cKg1cvVFj+lccGuAW9FbqD11ds+I=; b=gfFjkSIKEfWi7MAhdWCayEWjriLubZPtNfeh0/dDcfkHxFSKc6ND//9t RxU8YNK9yiAWSyU+NHvO61cVD817SeAO1Y11jcT6L5etdfQW0eLJxxcM9 t8FicbIHK6j+Y9R8nlz7OBaN/eeNXaUKMKp4FzCe7H1aaKylUhwoZJ+Xn NgfY27Mm9iKKUn6HWBMvOoLrV7GLG4sM1o76H68lUb5SeQL17kexyvfaD 1tKfX1PbFn8iepigVk68JO4JelJ3fqsxkCK1zvrmWBSpkdBJSgTJvoEsR ghZq/gkgW3KCWHljkPCSrOkD4hVBNiiO6N3qZoIQwgSaOliUJmk4h5XbW Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10555"; a="297738640" X-IronPort-AV: E=Sophos;i="5.96,230,1665471600"; d="scan'208";a="297738640" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Dec 2022 21:45:28 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10555"; a="640911691" X-IronPort-AV: E=Sophos;i="5.96,230,1665471600"; d="scan'208";a="640911691" Received: from yy-desk-7060.sh.intel.com (HELO localhost) ([10.239.159.76]) by orsmga007.jf.intel.com with ESMTP; 08 Dec 2022 21:45:18 -0800 Date: Fri, 9 Dec 2022 13:45:17 +0800 From: Yuan Yao To: Chao Peng Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, Paolo Bonzini , Jonathan Corbet , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Arnd Bergmann , Naoya Horiguchi , Miaohe Lin , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Shuah Khan , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , tabba@google.com, Michael Roth , mhocko@suse.com, wei.w.wang@intel.com Subject: Re: [PATCH v10 8/9] KVM: Handle page fault for private memory Message-ID: <20221209054517.okw2epqx5s3yjnfp@yy-desk-7060> References: <20221202061347.1070246-1-chao.p.peng@linux.intel.com> <20221202061347.1070246-9-chao.p.peng@linux.intel.com> <20221208022918.fbddl3bflsip4ivg@yy-desk-7060> <20221208112346.GD1304936@chaop.bj.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221208112346.GD1304936@chaop.bj.intel.com> User-Agent: NeoMutt/20171215 X-Spam-Status: No, score=-4.3 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 08, 2022 at 07:23:46PM +0800, Chao Peng wrote: > On Thu, Dec 08, 2022 at 10:29:18AM +0800, Yuan Yao wrote: > > On Fri, Dec 02, 2022 at 02:13:46PM +0800, Chao Peng wrote: > > > A KVM_MEM_PRIVATE memslot can include both fd-based private memory and > > > hva-based shared memory. Architecture code (like TDX code) can tell > > > whether the on-going fault is private or not. This patch adds a > > > 'is_private' field to kvm_page_fault to indicate this and architecture > > > code is expected to set it. > > > > > > To handle page fault for such memslot, the handling logic is different > > > depending on whether the fault is private or shared. KVM checks if > > > 'is_private' matches the host's view of the page (maintained in > > > mem_attr_array). > > > - For a successful match, private pfn is obtained with > > > restrictedmem_get_page() and shared pfn is obtained with existing > > > get_user_pages(). > > > - For a failed match, KVM causes a KVM_EXIT_MEMORY_FAULT exit to > > > userspace. Userspace then can convert memory between private/shared > > > in host's view and retry the fault. > > > > > > Co-developed-by: Yu Zhang > > > Signed-off-by: Yu Zhang > > > Signed-off-by: Chao Peng > > > --- > > > arch/x86/kvm/mmu/mmu.c | 63 +++++++++++++++++++++++++++++++-- > > > arch/x86/kvm/mmu/mmu_internal.h | 14 +++++++- > > > arch/x86/kvm/mmu/mmutrace.h | 1 + > > > arch/x86/kvm/mmu/tdp_mmu.c | 2 +- > > > include/linux/kvm_host.h | 30 ++++++++++++++++ > > > 5 files changed, 105 insertions(+), 5 deletions(-) > > > > > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > > > index 2190fd8c95c0..b1953ebc012e 100644 > > > --- a/arch/x86/kvm/mmu/mmu.c > > > +++ b/arch/x86/kvm/mmu/mmu.c > > > @@ -3058,7 +3058,7 @@ static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, > > > > > > int kvm_mmu_max_mapping_level(struct kvm *kvm, > > > const struct kvm_memory_slot *slot, gfn_t gfn, > > > - int max_level) > > > + int max_level, bool is_private) > > > { > > > struct kvm_lpage_info *linfo; > > > int host_level; > > > @@ -3070,6 +3070,9 @@ int kvm_mmu_max_mapping_level(struct kvm *kvm, > > > break; > > > } > > > > > > + if (is_private) > > > + return max_level; > > > > lpage mixed information already saved, so is that possible > > to query info->disallow_lpage without care 'is_private' ? > > Actually we already queried info->disallow_lpage just before this > sentence. The check is needed because later in the function we call > host_pfn_mapping_level() which is shared memory specific. You're right. We can't get mapping level info for private page from host_pfn_mapping_level(). > > Thanks, > Chao > > > > > + > > > if (max_level == PG_LEVEL_4K) > > > return PG_LEVEL_4K; > > > > > > @@ -3098,7 +3101,8 @@ void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > > > * level, which will be used to do precise, accurate accounting. > > > */ > > > fault->req_level = kvm_mmu_max_mapping_level(vcpu->kvm, slot, > > > - fault->gfn, fault->max_level); > > > + fault->gfn, fault->max_level, > > > + fault->is_private); > > > if (fault->req_level == PG_LEVEL_4K || fault->huge_page_disallowed) > > > return; > > > > > > @@ -4178,6 +4182,49 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) > > > kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, 0, true); > > > } > > > > > > +static inline u8 order_to_level(int order) > > > +{ > > > + BUILD_BUG_ON(KVM_MAX_HUGEPAGE_LEVEL > PG_LEVEL_1G); > > > + > > > + if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_1G)) > > > + return PG_LEVEL_1G; > > > + > > > + if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_2M)) > > > + return PG_LEVEL_2M; > > > + > > > + return PG_LEVEL_4K; > > > +} > > > + > > > +static int kvm_do_memory_fault_exit(struct kvm_vcpu *vcpu, > > > + struct kvm_page_fault *fault) > > > +{ > > > + vcpu->run->exit_reason = KVM_EXIT_MEMORY_FAULT; > > > + if (fault->is_private) > > > + vcpu->run->memory.flags = KVM_MEMORY_EXIT_FLAG_PRIVATE; > > > + else > > > + vcpu->run->memory.flags = 0; > > > + vcpu->run->memory.gpa = fault->gfn << PAGE_SHIFT; > > > + vcpu->run->memory.size = PAGE_SIZE; > > > + return RET_PF_USER; > > > +} > > > + > > > +static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu, > > > + struct kvm_page_fault *fault) > > > +{ > > > + int order; > > > + struct kvm_memory_slot *slot = fault->slot; > > > + > > > + if (!kvm_slot_can_be_private(slot)) > > > + return kvm_do_memory_fault_exit(vcpu, fault); > > > + > > > + if (kvm_restricted_mem_get_pfn(slot, fault->gfn, &fault->pfn, &order)) > > > + return RET_PF_RETRY; > > > + > > > + fault->max_level = min(order_to_level(order), fault->max_level); > > > + fault->map_writable = !(slot->flags & KVM_MEM_READONLY); > > > + return RET_PF_CONTINUE; > > > +} > > > + > > > static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) > > > { > > > struct kvm_memory_slot *slot = fault->slot; > > > @@ -4210,6 +4257,12 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) > > > return RET_PF_EMULATE; > > > } > > > > > > + if (fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) > > > + return kvm_do_memory_fault_exit(vcpu, fault); > > > + > > > + if (fault->is_private) > > > + return kvm_faultin_pfn_private(vcpu, fault); > > > + > > > async = false; > > > fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, false, &async, > > > fault->write, &fault->map_writable, > > > @@ -5599,6 +5652,9 @@ int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 err > > > return -EIO; > > > } > > > > > > + if (r == RET_PF_USER) > > > + return 0; > > > + > > > if (r < 0) > > > return r; > > > if (r != RET_PF_EMULATE) > > > @@ -6452,7 +6508,8 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm, > > > */ > > > if (sp->role.direct && > > > sp->role.level < kvm_mmu_max_mapping_level(kvm, slot, sp->gfn, > > > - PG_LEVEL_NUM)) { > > > + PG_LEVEL_NUM, > > > + false)) { > > > kvm_zap_one_rmap_spte(kvm, rmap_head, sptep); > > > > > > if (kvm_available_flush_tlb_with_range()) > > > diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h > > > index dbaf6755c5a7..5ccf08183b00 100644 > > > --- a/arch/x86/kvm/mmu/mmu_internal.h > > > +++ b/arch/x86/kvm/mmu/mmu_internal.h > > > @@ -189,6 +189,7 @@ struct kvm_page_fault { > > > > > > /* Derived from mmu and global state. */ > > > const bool is_tdp; > > > + const bool is_private; > > > const bool nx_huge_page_workaround_enabled; > > > > > > /* > > > @@ -237,6 +238,7 @@ int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); > > > * RET_PF_RETRY: let CPU fault again on the address. > > > * RET_PF_EMULATE: mmio page fault, emulate the instruction directly. > > > * RET_PF_INVALID: the spte is invalid, let the real page fault path update it. > > > + * RET_PF_USER: need to exit to userspace to handle this fault. > > > * RET_PF_FIXED: The faulting entry has been fixed. > > > * RET_PF_SPURIOUS: The faulting entry was already fixed, e.g. by another vCPU. > > > * > > > @@ -253,6 +255,7 @@ enum { > > > RET_PF_RETRY, > > > RET_PF_EMULATE, > > > RET_PF_INVALID, > > > + RET_PF_USER, > > > RET_PF_FIXED, > > > RET_PF_SPURIOUS, > > > }; > > > @@ -310,7 +313,7 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, > > > > > > int kvm_mmu_max_mapping_level(struct kvm *kvm, > > > const struct kvm_memory_slot *slot, gfn_t gfn, > > > - int max_level); > > > + int max_level, bool is_private); > > > void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); > > > void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level); > > > > > > @@ -319,4 +322,13 @@ void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc); > > > void track_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp); > > > void untrack_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp); > > > > > > +#ifndef CONFIG_HAVE_KVM_RESTRICTED_MEM > > > +static inline int kvm_restricted_mem_get_pfn(struct kvm_memory_slot *slot, > > > + gfn_t gfn, kvm_pfn_t *pfn, int *order) > > > +{ > > > + WARN_ON_ONCE(1); > > > + return -EOPNOTSUPP; > > > +} > > > +#endif /* CONFIG_HAVE_KVM_RESTRICTED_MEM */ > > > + > > > #endif /* __KVM_X86_MMU_INTERNAL_H */ > > > diff --git a/arch/x86/kvm/mmu/mmutrace.h b/arch/x86/kvm/mmu/mmutrace.h > > > index ae86820cef69..2d7555381955 100644 > > > --- a/arch/x86/kvm/mmu/mmutrace.h > > > +++ b/arch/x86/kvm/mmu/mmutrace.h > > > @@ -58,6 +58,7 @@ TRACE_DEFINE_ENUM(RET_PF_CONTINUE); > > > TRACE_DEFINE_ENUM(RET_PF_RETRY); > > > TRACE_DEFINE_ENUM(RET_PF_EMULATE); > > > TRACE_DEFINE_ENUM(RET_PF_INVALID); > > > +TRACE_DEFINE_ENUM(RET_PF_USER); > > > TRACE_DEFINE_ENUM(RET_PF_FIXED); > > > TRACE_DEFINE_ENUM(RET_PF_SPURIOUS); > > > > > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > > > index 771210ce5181..8ba1a4afc546 100644 > > > --- a/arch/x86/kvm/mmu/tdp_mmu.c > > > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > > > @@ -1768,7 +1768,7 @@ static void zap_collapsible_spte_range(struct kvm *kvm, > > > continue; > > > > > > max_mapping_level = kvm_mmu_max_mapping_level(kvm, slot, > > > - iter.gfn, PG_LEVEL_NUM); > > > + iter.gfn, PG_LEVEL_NUM, false); > > > if (max_mapping_level < iter.level) > > > continue; > > > > > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > > > index 25099c94e770..153842bb33df 100644 > > > --- a/include/linux/kvm_host.h > > > +++ b/include/linux/kvm_host.h > > > @@ -2335,4 +2335,34 @@ static inline void kvm_arch_set_memory_attributes(struct kvm *kvm, > > > } > > > #endif /* __KVM_HAVE_ARCH_SET_MEMORY_ATTRIBUTES */ > > > > > > +#ifdef CONFIG_HAVE_KVM_MEMORY_ATTRIBUTES > > > +static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn) > > > +{ > > > + return xa_to_value(xa_load(&kvm->mem_attr_array, gfn)) & > > > + KVM_MEMORY_ATTRIBUTE_PRIVATE; > > > +} > > > +#else > > > +static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn) > > > +{ > > > + return false; > > > +} > > > + > > > +#endif /* CONFIG_HAVE_KVM_MEMORY_ATTRIBUTES */ > > > + > > > +#ifdef CONFIG_HAVE_KVM_RESTRICTED_MEM > > > +static inline int kvm_restricted_mem_get_pfn(struct kvm_memory_slot *slot, > > > + gfn_t gfn, kvm_pfn_t *pfn, int *order) > > > +{ > > > + int ret; > > > + struct page *page; > > > + pgoff_t index = gfn - slot->base_gfn + > > > + (slot->restricted_offset >> PAGE_SHIFT); > > > + > > > + ret = restrictedmem_get_page(slot->restricted_file, index, > > > + &page, order); > > > + *pfn = page_to_pfn(page); > > > + return ret; > > > +} > > > +#endif /* CONFIG_HAVE_KVM_RESTRICTED_MEM */ > > > + > > > #endif > > > -- > > > 2.25.1 > > > > > >