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 4BB07C10F1B for ; Fri, 9 Dec 2022 09:01:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229907AbiLIJBs (ORCPT ); Fri, 9 Dec 2022 04:01:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60542 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229896AbiLIJBo (ORCPT ); Fri, 9 Dec 2022 04:01:44 -0500 Received: from mail-lf1-x131.google.com (mail-lf1-x131.google.com [IPv6:2a00:1450:4864:20::131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 21AF84B9AC for ; Fri, 9 Dec 2022 01:01:43 -0800 (PST) Received: by mail-lf1-x131.google.com with SMTP id bp15so5990073lfb.13 for ; Fri, 09 Dec 2022 01:01:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=tIXPe5cCY7SbH9t4zh9YfRDFW74YXHmGt3mg6nuUHqs=; b=VuB7/NfjD1Ipkn6u998+OqKbvnPKotmUXzEe7tZZDtTXhpIra2DNGiNpGlAB0+OBZk y3/S0P8PzOVuvzxnyBY33MMZ0nNJxQ/eyisHXUR3aYV5eZEnWYQQv8DsXm05t2dxOHMR Xj9w/HPUaq7OR/YEvWakKvQB8QyneguCsgyXe34bwrvjv3omrk3pqd5QMN7ot6NZG+Zu w7f/u+JA+j86+877JSdoaF4vg9uOvswCYYlmAJRZzCYQ6Rw6RgbarL2ydHkbrpAObrZA r6ggnWWYXHFpyxW+Ragom7YL8b16n0M0Cdh8u7nrXWRr75ji43GuvsJlNO9DBVfhE2Yj k3rQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=tIXPe5cCY7SbH9t4zh9YfRDFW74YXHmGt3mg6nuUHqs=; b=khU2d36nownIx/Lh6MdRT6RDIZ3kEszNnpKdiBOIBdcuKCbY1yvsZ3Pqv1BTmlJ0ek 7S1z1Gou6wL1FBlAoeJhJxUPJAm8HFukq9681nO4wRNHcTCi16z9aEvmJKIKnbjxHTm9 BbH6Gxk0BUK8F3DMm/5z+jjNw2HwLE4YKfA43NLKer5Fm7MTQqVh2bv9ePPIFxUlynMu Nnq1/yH2cLiBjUGy/k8Gl2jVSki/2q5dO9o6iL1RD2YP4A6guk4/kM5R9fpTr+U6To4Y H35CcvH+cjHBqLg9qt8KxSkO1hU43/qY8jJYbxfYAUYB5vak8dVz0U701w/7D1Opfphd 3+qA== X-Gm-Message-State: ANoB5plo1ZY7ZIRA9wVyj+PT1LmsMSEGAmcN9S81BQEg0nml1fytS3r4 7w+en81YmmY8ivorWebf6lOScor256gFPEyd7B/94Q== X-Google-Smtp-Source: AA0mqf6hsuR14V3LEbeqAQeYzNj60TICpsoaP0ASgnh6fJfrUOg3ORXgLeEGbpZXkkdwAlP9PKSiDr5FswDqTG/ntYE= X-Received: by 2002:a05:6512:3c99:b0:4b5:5ec5:10c0 with SMTP id h25-20020a0565123c9900b004b55ec510c0mr7959261lfv.355.1670576501107; Fri, 09 Dec 2022 01:01:41 -0800 (PST) MIME-Version: 1.0 References: <20221202061347.1070246-1-chao.p.peng@linux.intel.com> <20221202061347.1070246-9-chao.p.peng@linux.intel.com> In-Reply-To: <20221202061347.1070246-9-chao.p.peng@linux.intel.com> From: Fuad Tabba Date: Fri, 9 Dec 2022 09:01:04 +0000 Message-ID: Subject: Re: [PATCH v10 8/9] KVM: Handle page fault for private memory 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 , Michael Roth , mhocko@suse.com, wei.w.wang@intel.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi, On Fri, Dec 2, 2022 at 6:19 AM 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; > + > 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; nit: As in previous patches, use helpers (for this and other similar shifts in this patch)? > + 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 > With my limited understanding of x86 code: Reviewed-by: Fuad Tabba The common code in kvm_host.h was used in the port to arm64, and the x86 fault handling code was used as a guide to how it should be done in pKVM (with similar code added there). So with these caveats in mind: Tested-by: Fuad Tabba Cheers, /fuad