From: Tom Lendacky Date: Wed, 21 Feb 2018 19:39:51 +0000 (-0600) Subject: KVM: x86: Add a framework for supporting MSR-based features X-Git-Tag: v4.1.12-124.31.3~614 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=87d95a6c9aa75c5a632ce532c58b3c07403dd495;p=users%2Fjedix%2Flinux-maple.git KVM: x86: Add a framework for supporting MSR-based features Provide a new KVM capability that allows bits within MSRs to be recognized as features. Two new ioctls are added to the /dev/kvm ioctl routine to retrieve the list of these MSRs and then retrieve their values. A kvm_x86_ops callback is used to determine support for the listed MSR-based features. Signed-off-by: Tom Lendacky Signed-off-by: Paolo Bonzini [Tweaked documentation. - Radim] Signed-off-by: Radim Krčmář Orabug: 28220674 CVE: CVE-2018-3646 (cherry picked from commit 801e459a6f3a63af9d447e6249088c76ae16efc4) This was needed in order to backport commit cd28325249a1ca0d771557ce823e0308ad629f98. Signed-off-by: Mihai Carabas Reviewed-by: Darren Kenny Reviewed-by: Boris Ostrovsky Conflicts: arch/x86/include/asm/kvm_host.h arch/x86/kvm/svm.c arch/x86/kvm/vmx.c arch/x86/kvm/x86.c include/uapi/linux/kvm.h Contextual: different content --- diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 9fa2bf8c3f6f..51306df8a12f 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -122,14 +122,15 @@ KVM_CAP_S390_UCONTROL and use the flag KVM_VM_S390_UCONTROL as privileged user (CAP_SYS_ADMIN). -4.3 KVM_GET_MSR_INDEX_LIST +4.3 KVM_GET_MSR_INDEX_LIST, KVM_GET_MSR_FEATURE_INDEX_LIST -Capability: basic +Capability: basic, KVM_CAP_GET_MSR_FEATURES for KVM_GET_MSR_FEATURE_INDEX_LIST Architectures: x86 -Type: system +Type: system ioctl Parameters: struct kvm_msr_list (in/out) Returns: 0 on success; -1 on error Errors: + EFAULT: the msr index list cannot be read from or written to E2BIG: the msr index list is to be to fit in the array specified by the user. @@ -138,16 +139,23 @@ struct kvm_msr_list { __u32 indices[0]; }; -This ioctl returns the guest msrs that are supported. The list varies -by kvm version and host processor, but does not change otherwise. The -user fills in the size of the indices array in nmsrs, and in return -kvm adjusts nmsrs to reflect the actual number of msrs and fills in -the indices array with their numbers. +The user fills in the size of the indices array in nmsrs, and in return +kvm adjusts nmsrs to reflect the actual number of msrs and fills in the +indices array with their numbers. + +KVM_GET_MSR_INDEX_LIST returns the guest msrs that are supported. The list +varies by kvm version and host processor, but does not change otherwise. Note: if kvm indicates supports MCE (KVM_CAP_MCE), then the MCE bank MSRs are not returned in the MSR list, as different vcpus can have a different number of banks, as set via the KVM_X86_SETUP_MCE ioctl. +KVM_GET_MSR_FEATURE_INDEX_LIST returns the list of MSRs that can be passed +to the KVM_GET_MSRS system ioctl. This lets userspace probe host capabilities +and processor features that are exposed via MSRs (e.g., VMX capabilities). +This list also varies by kvm version and host processor, but does not change +otherwise. + 4.4 KVM_CHECK_EXTENSION @@ -457,14 +465,22 @@ Support for this has been removed. Use KVM_SET_GUEST_DEBUG instead. 4.18 KVM_GET_MSRS -Capability: basic +Capability: basic (vcpu), KVM_CAP_GET_MSR_FEATURES (system) Architectures: x86 -Type: vcpu ioctl +Type: system ioctl, vcpu ioctl Parameters: struct kvm_msrs (in/out) -Returns: 0 on success, -1 on error +Returns: number of msrs successfully returned; + -1 on error + +When used as a system ioctl: +Reads the values of MSR-based features that are available for the VM. This +is similar to KVM_GET_SUPPORTED_CPUID, but it returns MSR indices and values. +The list of msr-based features can be obtained using KVM_GET_MSR_FEATURE_INDEX_LIST +in a system ioctl. +When used as a vcpu ioctl: Reads model-specific registers from the vcpu. Supported msr indices can -be obtained using KVM_GET_MSR_INDEX_LIST. +be obtained using KVM_GET_MSR_INDEX_LIST in a system ioctl. struct kvm_msrs { __u32 nmsrs; /* number of msrs in entries */ diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 004c70549d48..b5200f517f61 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -846,6 +846,7 @@ struct kvm_x86_ops { void (*enable_log_dirty_pt_masked)(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t offset, unsigned long mask); + int (*get_msr_feature)(struct kvm_msr_entry *entry); }; struct kvm_arch_async_pf { diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index fd56cdaf6496..f326bb9bc5d1 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -3107,6 +3107,11 @@ static u64 svm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc) svm_scale_tsc(vcpu, host_tsc); } +static int svm_get_msr_feature(struct kvm_msr_entry *msr) +{ + return 1; +} + static int svm_get_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 *data) { struct vcpu_svm *svm = to_svm(vcpu); @@ -4449,6 +4454,7 @@ static struct kvm_x86_ops svm_x86_ops = { .vcpu_put = svm_vcpu_put, .update_db_bp_intercept = update_bp_intercept, + .get_msr_feature = svm_get_msr_feature, .get_msr = svm_get_msr, .set_msr = svm_set_msr, .get_segment_base = svm_get_segment_base, diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index dbaf710c605c..6087eb0a7e4f 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2810,6 +2810,11 @@ static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata) return 0; } +static int vmx_get_msr_feature(struct kvm_msr_entry *msr) +{ + return 1; +} + /* * Reads an msr value (of 'msr_index') into 'pdata'. * Returns 0 on success, non-0 otherwise. @@ -10599,6 +10604,7 @@ static struct kvm_x86_ops vmx_x86_ops = { .vcpu_put = vmx_vcpu_put, .update_db_bp_intercept = update_exception_bitmap, + .get_msr_feature = vmx_get_msr_feature, .get_msr = vmx_get_msr, .set_msr = vmx_set_msr, .get_segment_base = vmx_get_segment_base, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b05535b2871c..debb9ec67875 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -965,6 +965,28 @@ static const u32 emulated_msrs[] = { MSR_IA32_MCG_CTL, }; +/* + * List of msr numbers which are used to expose MSR-based features that + * can be used by a hypervisor to validate requested CPU features. + */ +static u32 msr_based_features[] = { +}; + +static unsigned int num_msr_based_features; + +static int do_get_msr_feature(struct kvm_vcpu *vcpu, unsigned index, u64 *data) +{ + struct kvm_msr_entry msr; + + msr.index = index; + if (kvm_x86_ops->get_msr_feature(&msr)) + return 1; + + *data = msr.data; + + return 0; +} + bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer) { if (efer & efer_reserved_bits) @@ -2725,13 +2747,11 @@ static int __msr_io(struct kvm_vcpu *vcpu, struct kvm_msrs *msrs, int (*do_msr)(struct kvm_vcpu *vcpu, unsigned index, u64 *data)) { - int i, idx; + int i; - idx = srcu_read_lock(&vcpu->kvm->srcu); for (i = 0; i < msrs->nmsrs; ++i) if (do_msr(vcpu, entries[i].index, &entries[i].data)) break; - srcu_read_unlock(&vcpu->kvm->srcu, idx); return i; } @@ -2827,6 +2847,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_ASSIGN_DEV_IRQ: case KVM_CAP_PCI_2_3: #endif + case KVM_CAP_GET_MSR_FEATURES: r = 1; break; case KVM_CAP_COALESCED_MMIO: @@ -2931,6 +2952,31 @@ long kvm_arch_dev_ioctl(struct file *filp, goto out; r = 0; break; + case KVM_GET_MSR_FEATURE_INDEX_LIST: { + struct kvm_msr_list __user *user_msr_list = argp; + struct kvm_msr_list msr_list; + unsigned int n; + + r = -EFAULT; + if (copy_from_user(&msr_list, user_msr_list, sizeof(msr_list))) + goto out; + n = msr_list.nmsrs; + msr_list.nmsrs = num_msr_based_features; + if (copy_to_user(user_msr_list, &msr_list, sizeof(msr_list))) + goto out; + r = -E2BIG; + if (n < msr_list.nmsrs) + goto out; + r = -EFAULT; + if (copy_to_user(user_msr_list->indices, &msr_based_features, + num_msr_based_features * sizeof(u32))) + goto out; + r = 0; + break; + } + case KVM_GET_MSRS: + r = msr_io(NULL, argp, do_get_msr_feature, 1); + break; } default: r = -EINVAL; @@ -3483,12 +3529,18 @@ long kvm_arch_vcpu_ioctl(struct file *filp, r = 0; break; } - case KVM_GET_MSRS: + case KVM_GET_MSRS: { + int idx = srcu_read_lock(&vcpu->kvm->srcu); r = msr_io(vcpu, argp, kvm_get_msr, 1); + srcu_read_unlock(&vcpu->kvm->srcu, idx); break; - case KVM_SET_MSRS: + } + case KVM_SET_MSRS: { + int idx = srcu_read_lock(&vcpu->kvm->srcu); r = msr_io(vcpu, argp, do_set_msr, 0); + srcu_read_unlock(&vcpu->kvm->srcu, idx); break; + } case KVM_TPR_ACCESS_REPORTING: { struct kvm_tpr_access_ctl tac; @@ -4168,6 +4220,19 @@ static void kvm_init_msr_list(void) j++; } num_msrs_to_save = j; + + for (i = j = 0; i < ARRAY_SIZE(msr_based_features); i++) { + struct kvm_msr_entry msr; + + msr.index = msr_based_features[i]; + if (kvm_x86_ops->get_msr_feature(&msr)) + continue; + + if (j < i) + msr_based_features[j] = msr_based_features[i]; + j++; + } + num_msr_based_features = j; } static int vcpu_mmio_write(struct kvm_vcpu *vcpu, gpa_t addr, int len, diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 4b60056776d1..4f79eb2724b4 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -678,6 +678,7 @@ struct kvm_ppc_smmu_info { #define KVM_TRACE_PAUSE __KVM_DEPRECATED_MAIN_0x07 #define KVM_TRACE_DISABLE __KVM_DEPRECATED_MAIN_0x08 #define KVM_GET_EMULATED_CPUID _IOWR(KVMIO, 0x09, struct kvm_cpuid2) +#define KVM_GET_MSR_FEATURE_INDEX_LIST _IOWR(KVMIO, 0x0a, struct kvm_msr_list) /* * Extension capability list. @@ -814,6 +815,9 @@ struct kvm_ppc_smmu_info { #define KVM_CAP_S390_INJECT_IRQ 113 #define KVM_CAP_S390_IRQ_STATE 114 #define KVM_CAP_PPC_HWRNG 115 +#define KVM_CAP_PPC_GET_CPU_CHAR 151 +#define KVM_CAP_S390_BPB 152 +#define KVM_CAP_GET_MSR_FEATURES 153 #ifdef KVM_CAP_IRQ_ROUTING