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 C2288C6FD1A for ; Tue, 7 Mar 2023 19:28:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234053AbjCGT22 (ORCPT ); Tue, 7 Mar 2023 14:28:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234159AbjCGT2J (ORCPT ); Tue, 7 Mar 2023 14:28:09 -0500 Received: from mail-pj1-x104a.google.com (mail-pj1-x104a.google.com [IPv6:2607:f8b0:4864:20::104a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 37E81B5FEE for ; Tue, 7 Mar 2023 11:14:10 -0800 (PST) Received: by mail-pj1-x104a.google.com with SMTP id pl10-20020a17090b268a00b00239ed042afcso8524445pjb.4 for ; Tue, 07 Mar 2023 11:14:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1678216446; h=cc:to:from:subject:message-id:mime-version:in-reply-to:date:from:to :cc:subject:date:message-id:reply-to; bh=Wt+tMy1RH9zC84sq0to0cY0x7+Xv2yMTzgsmC8ZQ7cM=; b=D+BRUMlsQmhPM7Km19r0cwtSovSQv0WAERIfkRDuEbsEadkI29Rz8sSQqIRpfAPEa/ uCEsFKnPst88VAZKSkPZjffh5S3WZTxUmNU4Xw/KSiy4soV/n0dJgIrEl9OXSPbIfQQK KLOBXvGg6LH2ugOhFB2E2wpPrpDgxCLKWf0LPJlLMfhxqqsHvu6JPcw14TUVTqqyGFlZ BGsXgEkUEMCjAYmlzNQrRRX203Kz1uOE6SMPxmDIVc7khBpDDg6yCWpgZR7rxAtYpjv/ SqkEiQXtopyaQBB3xjjHp9QzaFJ66vn2U3nSuUXKNCqd3tZoY5qhFiJPfWWt4zAY4ldo w8FQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678216446; h=cc:to:from:subject:message-id:mime-version:in-reply-to:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Wt+tMy1RH9zC84sq0to0cY0x7+Xv2yMTzgsmC8ZQ7cM=; b=xwVNkMnf8jx3YCytY24CYvpehNuaea24tPnW5arfMSO3MDJegzWvhR2RiyHcQFI+w1 Jh+qw976ZkvLzR2ZRF07QCpu2cwGZM6dvFqa2kNiT+fOUdN3pJhOaIFZNF+mbCLQPTBW KsB9g6jYZzMApAzqxPGotJNj0fzKaKgwIvoDrD0SdM+qF66COKv67np8Sf8aePgwXIjq iMxQMBs6A1uqQQjF8twIpXMmiQ0VnCmdsLAsrmVYuCKbJ4neUpQtAMhguyD3sQ03L2b2 8qdntVF0nZth4XDaKgW+yd5hBZ/cEQLjSiOgXhJz5NKcWK/130hMAv0ChdvoNQRAWnbG 5qXQ== X-Gm-Message-State: AO0yUKW0BTCYbHB+HbzCcRVyt0K8Waxftd9lytbtHbSPxTovHyln9eZf 2s296qNBBog3Sl0kiS1wvnXZRNnUDbk3Ekf0bg== X-Google-Smtp-Source: AK7set9XmMrWXZ6mpUlbpcFneSpuxawFmXBvqn5A78lIM65RH9bBDorwkD1ukffGVS/euOjwrQaunWK8N4egR11Vkw== X-Received: from ackerleytng-cloudtop.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:1f5f]) (user=ackerleytng job=sendgmr) by 2002:a17:90a:8e83:b0:237:1fe0:b151 with SMTP id f3-20020a17090a8e8300b002371fe0b151mr5483530pjo.8.1678216446569; Tue, 07 Mar 2023 11:14:06 -0800 (PST) Date: Tue, 07 Mar 2023 19:14:05 +0000 In-Reply-To: <20221202061347.1070246-10-chao.p.peng@linux.intel.com> (message from Chao Peng on Fri, 2 Dec 2022 14:13:47 +0800) Mime-Version: 1.0 Message-ID: Subject: Re: [PATCH v10 9/9] KVM: Enable and expose KVM_MEM_PRIVATE From: Ackerley Tng 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, pbonzini@redhat.com, corbet@lwn.net, seanjc@google.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, arnd@arndb.de, naoya.horiguchi@nec.com, linmiaohe@huawei.com, x86@kernel.org, hpa@zytor.com, hughd@google.com, jlayton@kernel.org, bfields@fieldses.org, akpm@linux-foundation.org, shuah@kernel.org, rppt@kernel.org, steven.price@arm.com, mail@maciej.szmigiero.name, vbabka@suse.cz, vannapurve@google.com, yu.c.zhang@linux.intel.com, chao.p.peng@linux.intel.com, kirill.shutemov@linux.intel.com, 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, qperret@google.com, tabba@google.com, michael.roth@amd.com, mhocko@suse.com, wei.w.wang@intel.com Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org Chao Peng writes: > Register/unregister private memslot to fd-based memory backing store > restrictedmem and implement the callbacks for restrictedmem_notifier: > - invalidate_start()/invalidate_end() to zap the existing memory > mappings in the KVM page table. > - error() to request KVM_REQ_MEMORY_MCE and later exit to userspace > with KVM_EXIT_SHUTDOWN. > Expose KVM_MEM_PRIVATE for memslot and KVM_MEMORY_ATTRIBUTE_PRIVATE for > KVM_GET_SUPPORTED_MEMORY_ATTRIBUTES to userspace but either are > controlled by kvm_arch_has_private_mem() which should be rewritten by > architecture code. Could we perhaps rename KVM_MEM_PRIVATE to KVM_MEM_PROTECTED, to be in line with KVM_X86_PROTECTED_VM? I feel that a memslot that has the KVM_MEM_PRIVATE flag need not always be private; It can sometimes be providing memory that is shared and also accessible from the host. KVM_MEMORY_ATTRIBUTE_PRIVATE is fine as-is because this flag is set when the guest memory is meant to be backed by private memory. KVM_MEMORY_EXIT_FLAG_PRIVATE is also okay because the flag is used to indicate when the memory error is caused by a private access (as opposed to a shared access). kvm_slot_can_be_private() could perhaps be renamed kvm_is_protected_slot()? > Co-developed-by: Yu Zhang > Signed-off-by: Yu Zhang > Signed-off-by: Chao Peng > Reviewed-by: Fuad Tabba > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/x86.c | 13 +++ > include/linux/kvm_host.h | 3 + > virt/kvm/kvm_main.c | 179 +++++++++++++++++++++++++++++++- > 4 files changed, 191 insertions(+), 5 deletions(-) > diff --git a/arch/x86/include/asm/kvm_host.h > b/arch/x86/include/asm/kvm_host.h > index 7772ab37ac89..27ef31133352 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -114,6 +114,7 @@ > KVM_ARCH_REQ_FLAGS(31, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) > #define KVM_REQ_HV_TLB_FLUSH \ > KVM_ARCH_REQ_FLAGS(32, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) > +#define KVM_REQ_MEMORY_MCE KVM_ARCH_REQ(33) > #define CR0_RESERVED_BITS \ > (~(unsigned long)(X86_CR0_PE | X86_CR0_MP | X86_CR0_EM | X86_CR0_TS \ > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 5aefcff614d2..c67e22f3e2ee 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -6587,6 +6587,13 @@ int kvm_arch_pm_notifier(struct kvm *kvm, unsigned > long state) > } > #endif /* CONFIG_HAVE_KVM_PM_NOTIFIER */ > +#ifdef CONFIG_HAVE_KVM_RESTRICTED_MEM > +void kvm_arch_memory_mce(struct kvm *kvm) > +{ > + kvm_make_all_cpus_request(kvm, KVM_REQ_MEMORY_MCE); > +} > +#endif > + > static int kvm_vm_ioctl_get_clock(struct kvm *kvm, void __user *argp) > { > struct kvm_clock_data data = { 0 }; > @@ -10357,6 +10364,12 @@ static int vcpu_enter_guest(struct kvm_vcpu > *vcpu) > if (kvm_check_request(KVM_REQ_UPDATE_CPU_DIRTY_LOGGING, vcpu)) > static_call(kvm_x86_update_cpu_dirty_logging)(vcpu); > + > + if (kvm_check_request(KVM_REQ_MEMORY_MCE, vcpu)) { > + vcpu->run->exit_reason = KVM_EXIT_SHUTDOWN; > + r = 0; > + goto out; > + } > } > if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win || > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 153842bb33df..f032d878e034 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -590,6 +590,7 @@ struct kvm_memory_slot { > struct file *restricted_file; > loff_t restricted_offset; > struct restrictedmem_notifier notifier; > + struct kvm *kvm; > }; > static inline bool kvm_slot_can_be_private(const struct kvm_memory_slot > *slot) > @@ -2363,6 +2364,8 @@ static inline int kvm_restricted_mem_get_pfn(struct > kvm_memory_slot *slot, > *pfn = page_to_pfn(page); > return ret; > } > + > +void kvm_arch_memory_mce(struct kvm *kvm); > #endif /* CONFIG_HAVE_KVM_RESTRICTED_MEM */ > #endif > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index e107afea32f0..ac835fc77273 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -936,6 +936,121 @@ static int kvm_init_mmu_notifier(struct kvm *kvm) > #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */ > +#ifdef CONFIG_HAVE_KVM_RESTRICTED_MEM > +static bool restrictedmem_range_is_valid(struct kvm_memory_slot *slot, > + pgoff_t start, pgoff_t end, > + gfn_t *gfn_start, gfn_t *gfn_end) > +{ > + unsigned long base_pgoff = slot->restricted_offset >> PAGE_SHIFT; > + > + if (start > base_pgoff) > + *gfn_start = slot->base_gfn + start - base_pgoff; > + else > + *gfn_start = slot->base_gfn; > + > + if (end < base_pgoff + slot->npages) > + *gfn_end = slot->base_gfn + end - base_pgoff; > + else > + *gfn_end = slot->base_gfn + slot->npages; > + > + if (*gfn_start >= *gfn_end) > + return false; > + > + return true; > +} > + > +static void kvm_restrictedmem_invalidate_begin(struct > restrictedmem_notifier *notifier, > + pgoff_t start, pgoff_t end) > +{ > + struct kvm_memory_slot *slot = container_of(notifier, > + struct kvm_memory_slot, > + notifier); > + struct kvm *kvm = slot->kvm; > + gfn_t gfn_start, gfn_end; > + struct kvm_gfn_range gfn_range; > + int idx; > + > + if (!restrictedmem_range_is_valid(slot, start, end, > + &gfn_start, &gfn_end)) > + return; > + > + gfn_range.start = gfn_start; > + gfn_range.end = gfn_end; > + gfn_range.slot = slot; > + gfn_range.pte = __pte(0); > + gfn_range.may_block = true; > + > + idx = srcu_read_lock(&kvm->srcu); > + KVM_MMU_LOCK(kvm); > + > + kvm_mmu_invalidate_begin(kvm); > + kvm_mmu_invalidate_range_add(kvm, gfn_start, gfn_end); > + if (kvm_unmap_gfn_range(kvm, &gfn_range)) > + kvm_flush_remote_tlbs(kvm); > + > + KVM_MMU_UNLOCK(kvm); > + srcu_read_unlock(&kvm->srcu, idx); > +} > + > +static void kvm_restrictedmem_invalidate_end(struct > restrictedmem_notifier *notifier, > + pgoff_t start, pgoff_t end) > +{ > + struct kvm_memory_slot *slot = container_of(notifier, > + struct kvm_memory_slot, > + notifier); > + struct kvm *kvm = slot->kvm; > + gfn_t gfn_start, gfn_end; > + > + if (!restrictedmem_range_is_valid(slot, start, end, > + &gfn_start, &gfn_end)) > + return; > + > + KVM_MMU_LOCK(kvm); > + kvm_mmu_invalidate_end(kvm); > + KVM_MMU_UNLOCK(kvm); > +} > + > +static void kvm_restrictedmem_error(struct restrictedmem_notifier > *notifier, > + pgoff_t start, pgoff_t end) > +{ > + struct kvm_memory_slot *slot = container_of(notifier, > + struct kvm_memory_slot, > + notifier); > + kvm_arch_memory_mce(slot->kvm); > +} > + > +static struct restrictedmem_notifier_ops kvm_restrictedmem_notifier_ops > = { > + .invalidate_start = kvm_restrictedmem_invalidate_begin, > + .invalidate_end = kvm_restrictedmem_invalidate_end, > + .error = kvm_restrictedmem_error, > +}; > + > +static inline void kvm_restrictedmem_register(struct kvm_memory_slot > *slot) > +{ > + slot->notifier.ops = &kvm_restrictedmem_notifier_ops; > + restrictedmem_register_notifier(slot->restricted_file, &slot->notifier); > +} > + > +static inline void kvm_restrictedmem_unregister(struct kvm_memory_slot > *slot) > +{ > + restrictedmem_unregister_notifier(slot->restricted_file, > + &slot->notifier); > +} > + > +#else /* !CONFIG_HAVE_KVM_RESTRICTED_MEM */ > + > +static inline void kvm_restrictedmem_register(struct kvm_memory_slot > *slot) > +{ > + WARN_ON_ONCE(1); > +} > + > +static inline void kvm_restrictedmem_unregister(struct kvm_memory_slot > *slot) > +{ > + WARN_ON_ONCE(1); > +} > + > +#endif /* CONFIG_HAVE_KVM_RESTRICTED_MEM */ > + > #ifdef CONFIG_HAVE_KVM_PM_NOTIFIER > static int kvm_pm_notifier_call(struct notifier_block *bl, > unsigned long state, > @@ -980,6 +1095,11 @@ static void kvm_destroy_dirty_bitmap(struct > kvm_memory_slot *memslot) > /* This does not remove the slot from struct kvm_memslots data > structures */ > static void kvm_free_memslot(struct kvm *kvm, struct kvm_memory_slot > *slot) > { > + if (slot->flags & KVM_MEM_PRIVATE) { > + kvm_restrictedmem_unregister(slot); > + fput(slot->restricted_file); > + } > + > kvm_destroy_dirty_bitmap(slot); > kvm_arch_free_memslot(kvm, slot); > @@ -1551,10 +1671,14 @@ static void kvm_replace_memslot(struct kvm *kvm, > } > } > -static int check_memory_region_flags(const struct kvm_user_mem_region > *mem) > +static int check_memory_region_flags(struct kvm *kvm, > + const struct kvm_user_mem_region *mem) > { > u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES; > + if (kvm_arch_has_private_mem(kvm)) > + valid_flags |= KVM_MEM_PRIVATE; > + > #ifdef __KVM_HAVE_READONLY_MEM > valid_flags |= KVM_MEM_READONLY; > #endif > @@ -1630,6 +1754,9 @@ static int kvm_prepare_memory_region(struct kvm > *kvm, > { > int r; > + if (change == KVM_MR_CREATE && new->flags & KVM_MEM_PRIVATE) > + kvm_restrictedmem_register(new); > + > /* > * If dirty logging is disabled, nullify the bitmap; the old bitmap > * will be freed on "commit". If logging is enabled in both old and > @@ -1658,6 +1785,9 @@ static int kvm_prepare_memory_region(struct kvm > *kvm, > if (r && new && new->dirty_bitmap && (!old || !old->dirty_bitmap)) > kvm_destroy_dirty_bitmap(new); > + if (r && change == KVM_MR_CREATE && new->flags & KVM_MEM_PRIVATE) > + kvm_restrictedmem_unregister(new); > + > return r; > } > @@ -1963,7 +2093,7 @@ int __kvm_set_memory_region(struct kvm *kvm, > int as_id, id; > int r; > - r = check_memory_region_flags(mem); > + r = check_memory_region_flags(kvm, mem); > if (r) > return r; > @@ -1982,6 +2112,10 @@ int __kvm_set_memory_region(struct kvm *kvm, > !access_ok((void __user *)(unsigned long)mem->userspace_addr, > mem->memory_size)) > return -EINVAL; > + if (mem->flags & KVM_MEM_PRIVATE && > + (mem->restricted_offset & (PAGE_SIZE - 1) || > + mem->restricted_offset > U64_MAX - mem->memory_size)) > + return -EINVAL; > if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM) > return -EINVAL; > if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr) > @@ -2020,6 +2154,9 @@ int __kvm_set_memory_region(struct kvm *kvm, > if ((kvm->nr_memslot_pages + npages) < kvm->nr_memslot_pages) > return -EINVAL; > } else { /* Modify an existing slot. */ > + /* Private memslots are immutable, they can only be deleted. */ > + if (mem->flags & KVM_MEM_PRIVATE) > + return -EINVAL; > if ((mem->userspace_addr != old->userspace_addr) || > (npages != old->npages) || > ((mem->flags ^ old->flags) & KVM_MEM_READONLY)) > @@ -2048,10 +2185,28 @@ int __kvm_set_memory_region(struct kvm *kvm, > new->npages = npages; > new->flags = mem->flags; > new->userspace_addr = mem->userspace_addr; > + if (mem->flags & KVM_MEM_PRIVATE) { > + new->restricted_file = fget(mem->restricted_fd); > + if (!new->restricted_file || > + !file_is_restrictedmem(new->restricted_file)) { > + r = -EINVAL; > + goto out; > + } > + new->restricted_offset = mem->restricted_offset; > + } > + > + new->kvm = kvm; > r = kvm_set_memslot(kvm, old, new, change); > if (r) > - kfree(new); > + goto out; > + > + return 0; > + > +out: > + if (new->restricted_file) > + fput(new->restricted_file); > + kfree(new); > return r; > } > EXPORT_SYMBOL_GPL(__kvm_set_memory_region); > @@ -2351,6 +2506,8 @@ static int kvm_vm_ioctl_clear_dirty_log(struct kvm > *kvm, > #ifdef CONFIG_HAVE_KVM_MEMORY_ATTRIBUTES > static u64 kvm_supported_mem_attributes(struct kvm *kvm) > { > + if (kvm_arch_has_private_mem(kvm)) > + return KVM_MEMORY_ATTRIBUTE_PRIVATE; > return 0; > } > @@ -4822,16 +4979,28 @@ static long kvm_vm_ioctl(struct file *filp, > } > case KVM_SET_USER_MEMORY_REGION: { > struct kvm_user_mem_region mem; > - unsigned long size = sizeof(struct kvm_userspace_memory_region); > + unsigned int flags_offset = offsetof(typeof(mem), flags); > + unsigned long size; > + u32 flags; > kvm_sanity_check_user_mem_region_alias(); > + memset(&mem, 0, sizeof(mem)); > + > r = -EFAULT; > + if (get_user(flags, (u32 __user *)(argp + flags_offset))) > + goto out; > + > + if (flags & KVM_MEM_PRIVATE) > + size = sizeof(struct kvm_userspace_memory_region_ext); > + else > + size = sizeof(struct kvm_userspace_memory_region); > + > if (copy_from_user(&mem, argp, size)) > goto out; > r = -EINVAL; > - if (mem.flags & KVM_MEM_PRIVATE) > + if ((flags ^ mem.flags) & KVM_MEM_PRIVATE) > goto out; > r = kvm_vm_ioctl_set_memory_region(kvm, &mem);