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Mon, 30 Mar 2020 06:22:32 +0000 From: Ashish Kalra To: pbonzini@redhat.com Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, joro@8bytes.org, bp@suse.de, thomas.lendacky@amd.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, rientjes@google.com, srutherford@google.com, luto@kernel.org, brijesh.singh@amd.com Subject: [PATCH v6 09/14] KVM: x86: Introduce KVM_GET_PAGE_ENC_BITMAP ioctl Date: Mon, 30 Mar 2020 06:22:23 +0000 Message-Id: <388afbf3af3a10cc3101008bc9381491cc7aab2f.1585548051.git.ashish.kalra@amd.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: References: X-ClientProxiedBy: DM5PR04CA0051.namprd04.prod.outlook.com (2603:10b6:3:ef::13) To DM5PR12MB1386.namprd12.prod.outlook.com (2603:10b6:3:77::9) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from ashkalra_ubuntu_server.amd.com (165.204.77.1) by DM5PR04CA0051.namprd04.prod.outlook.com (2603:10b6:3:ef::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2856.20 via Frontend Transport; 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Return the correct bitmap as per the number of pages being requested by the user. Ensure that we only copy bmap->num_pages bytes in the userspace buffer, if bmap->num_pages is not byte aligned we read the trailing bits from the userspace and copy those bits as is. Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Paolo Bonzini Cc: "Radim Krčmář" Cc: Joerg Roedel Cc: Borislav Petkov Cc: Tom Lendacky Cc: x86@kernel.org Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Brijesh Singh Signed-off-by: Ashish Kalra Reviewed-by: Venu Busireddy Reviewed-by: Krish Sadhukhan --- Documentation/virt/kvm/api.rst | 27 +++++++++++++ arch/x86/include/asm/kvm_host.h | 2 + arch/x86/kvm/svm.c | 71 +++++++++++++++++++++++++++++++++ arch/x86/kvm/x86.c | 12 ++++++ include/uapi/linux/kvm.h | 12 ++++++ 5 files changed, 124 insertions(+) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index ebd383fba939..8ad800ebb54f 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -4648,6 +4648,33 @@ This ioctl resets VCPU registers and control structures according to the clear cpu reset definition in the POP. However, the cpu is not put into ESA mode. This reset is a superset of the initial reset. +4.125 KVM_GET_PAGE_ENC_BITMAP (vm ioctl) +--------------------------------------- + +:Capability: basic +:Architectures: x86 +:Type: vm ioctl +:Parameters: struct kvm_page_enc_bitmap (in/out) +:Returns: 0 on success, -1 on error + +/* for KVM_GET_PAGE_ENC_BITMAP */ +struct kvm_page_enc_bitmap { + __u64 start_gfn; + __u64 num_pages; + union { + void __user *enc_bitmap; /* one bit per page */ + __u64 padding2; + }; +}; + +The encrypted VMs have concept of private and shared pages. The private +page is encrypted with the guest-specific key, while shared page may +be encrypted with the hypervisor key. The KVM_GET_PAGE_ENC_BITMAP can +be used to get the bitmap indicating whether the guest page is private +or shared. The bitmap can be used during the guest migration, if the page +is private then userspace need to use SEV migration commands to transmit +the page. + 5. The kvm_run structure ======================== diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 90718fa3db47..27e43e3ec9d8 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1269,6 +1269,8 @@ struct kvm_x86_ops { int (*enable_direct_tlbflush)(struct kvm_vcpu *vcpu); int (*page_enc_status_hc)(struct kvm *kvm, unsigned long gpa, unsigned long sz, unsigned long mode); + int (*get_page_enc_bitmap)(struct kvm *kvm, + struct kvm_page_enc_bitmap *bmap); }; struct kvm_arch_async_pf { diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 1d8beaf1bceb..bae783cd396a 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -7686,6 +7686,76 @@ static int svm_page_enc_status_hc(struct kvm *kvm, unsigned long gpa, return ret; } +static int svm_get_page_enc_bitmap(struct kvm *kvm, + struct kvm_page_enc_bitmap *bmap) +{ + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + unsigned long gfn_start, gfn_end; + unsigned long sz, i, sz_bytes; + unsigned long *bitmap; + int ret, n; + + if (!sev_guest(kvm)) + return -ENOTTY; + + gfn_start = bmap->start_gfn; + gfn_end = gfn_start + bmap->num_pages; + + sz = ALIGN(bmap->num_pages, BITS_PER_LONG) / BITS_PER_BYTE; + bitmap = kmalloc(sz, GFP_KERNEL); + if (!bitmap) + return -ENOMEM; + + /* by default all pages are marked encrypted */ + memset(bitmap, 0xff, sz); + + mutex_lock(&kvm->lock); + if (sev->page_enc_bmap) { + i = gfn_start; + for_each_clear_bit_from(i, sev->page_enc_bmap, + min(sev->page_enc_bmap_size, gfn_end)) + clear_bit(i - gfn_start, bitmap); + } + mutex_unlock(&kvm->lock); + + ret = -EFAULT; + + n = bmap->num_pages % BITS_PER_BYTE; + sz_bytes = ALIGN(bmap->num_pages, BITS_PER_BYTE) / BITS_PER_BYTE; + + /* + * Return the correct bitmap as per the number of pages being + * requested by the user. Ensure that we only copy bmap->num_pages + * bytes in the userspace buffer, if bmap->num_pages is not byte + * aligned we read the trailing bits from the userspace and copy + * those bits as is. + */ + + if (n) { + unsigned char *bitmap_kernel = (unsigned char *)bitmap; + unsigned char bitmap_user; + unsigned long offset, mask; + + offset = bmap->num_pages / BITS_PER_BYTE; + if (copy_from_user(&bitmap_user, bmap->enc_bitmap + offset, + sizeof(unsigned char))) + goto out; + + mask = GENMASK(n - 1, 0); + bitmap_user &= ~mask; + bitmap_kernel[offset] &= mask; + bitmap_kernel[offset] |= bitmap_user; + } + + if (copy_to_user(bmap->enc_bitmap, bitmap, sz_bytes)) + goto out; + + ret = 0; +out: + kfree(bitmap); + return ret; +} + static int svm_mem_enc_op(struct kvm *kvm, void __user *argp) { struct kvm_sev_cmd sev_cmd; @@ -8090,6 +8160,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = { .apic_init_signal_blocked = svm_apic_init_signal_blocked, .page_enc_status_hc = svm_page_enc_status_hc, + .get_page_enc_bitmap = svm_get_page_enc_bitmap, }; static int __init svm_init(void) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 68428eef2dde..3c3fea4e20b5 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5226,6 +5226,18 @@ long kvm_arch_vm_ioctl(struct file *filp, case KVM_SET_PMU_EVENT_FILTER: r = kvm_vm_ioctl_set_pmu_event_filter(kvm, argp); break; + case KVM_GET_PAGE_ENC_BITMAP: { + struct kvm_page_enc_bitmap bitmap; + + r = -EFAULT; + if (copy_from_user(&bitmap, argp, sizeof(bitmap))) + goto out; + + r = -ENOTTY; + if (kvm_x86_ops->get_page_enc_bitmap) + r = kvm_x86_ops->get_page_enc_bitmap(kvm, &bitmap); + break; + } default: r = -ENOTTY; } diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 4e80c57a3182..db1ebf85e177 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -500,6 +500,16 @@ struct kvm_dirty_log { }; }; +/* for KVM_GET_PAGE_ENC_BITMAP */ +struct kvm_page_enc_bitmap { + __u64 start_gfn; + __u64 num_pages; + union { + void __user *enc_bitmap; /* one bit per page */ + __u64 padding2; + }; +}; + /* for KVM_CLEAR_DIRTY_LOG */ struct kvm_clear_dirty_log { __u32 slot; @@ -1478,6 +1488,8 @@ struct kvm_enc_region { #define KVM_S390_NORMAL_RESET _IO(KVMIO, 0xc3) #define KVM_S390_CLEAR_RESET _IO(KVMIO, 0xc4) +#define KVM_GET_PAGE_ENC_BITMAP _IOW(KVMIO, 0xc5, struct kvm_page_enc_bitmap) + /* Secure Encrypted Virtualization command */ enum sev_cmd_id { /* Guest initialization commands */