diff options
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 4 | ||||
| -rw-r--r-- | arch/x86/include/uapi/asm/kvm.h | 3 | ||||
| -rw-r--r-- | arch/x86/kvm/xen.c | 9 |
3 files changed, 16 insertions, 0 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 2b52eb77e29c..5fe84f2427b5 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -1000,6 +1000,10 @@ blobs in userspace. When the guest writes the MSR, kvm copies one page of a blob (32- or 64-bit, depending on the vcpu mode) to guest memory. +The MSR index must be in the range [0x40000000, 0x4fffffff], i.e. must reside +in the range that is unofficially reserved for use by hypervisors. The min/max +values are enumerated via KVM_XEN_MSR_MIN_INDEX and KVM_XEN_MSR_MAX_INDEX. + :: struct kvm_xen_hvm_config { diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h index 9e75da97bce0..460306b35a4b 100644 --- a/arch/x86/include/uapi/asm/kvm.h +++ b/arch/x86/include/uapi/asm/kvm.h @@ -559,6 +559,9 @@ struct kvm_x86_mce { #define KVM_XEN_HVM_CONFIG_PVCLOCK_TSC_UNSTABLE (1 << 7) #define KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA (1 << 8) +#define KVM_XEN_MSR_MIN_INDEX 0x40000000u +#define KVM_XEN_MSR_MAX_INDEX 0x4fffffffu + struct kvm_xen_hvm_config { __u32 flags; __u32 msr; diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index a909b817b9c0..5b94825001a7 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -1324,6 +1324,15 @@ int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc) xhc->blob_size_32 || xhc->blob_size_64)) return -EINVAL; + /* + * Restrict the MSR to the range that is unofficially reserved for + * synthetic, virtualization-defined MSRs, e.g. to prevent confusing + * KVM by colliding with a real MSR that requires special handling. + */ + if (xhc->msr && + (xhc->msr < KVM_XEN_MSR_MIN_INDEX || xhc->msr > KVM_XEN_MSR_MAX_INDEX)) + return -EINVAL; + mutex_lock(&kvm->arch.xen.xen_lock); if (xhc->msr && !kvm->arch.xen_hvm_config.msr) |