From be83794210e7020fef98596f4513aafbed659cd1 Mon Sep 17 00:00:00 2001 From: Aaron Lewis Date: Wed, 21 Sep 2022 15:15:21 +0000 Subject: [PATCH] KVM: x86: Disallow the use of KVM_MSR_FILTER_DEFAULT_ALLOW in the kernel Protect the kernel from using the flag KVM_MSR_FILTER_DEFAULT_ALLOW. Its value is 0, and using it incorrectly could have unintended consequences. E.g. prevent someone in the kernel from writing something like this. if (filter.flags & KVM_MSR_FILTER_DEFAULT_ALLOW) and getting confused when it doesn't work. It would be more ideal to remove this flag altogether, but userspace may already be using it, so protecting the kernel is all that can reasonably be done at this point. Suggested-by: Sean Christopherson Signed-off-by: Aaron Lewis Reviewed-by: Sean Christopherson Message-Id: <20220921151525.904162-2-aaronlewis@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/uapi/asm/kvm.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h index 46de10a809ec..73ad693aa653 100644 --- a/arch/x86/include/uapi/asm/kvm.h +++ b/arch/x86/include/uapi/asm/kvm.h @@ -222,7 +222,9 @@ struct kvm_msr_filter_range { #define KVM_MSR_FILTER_MAX_RANGES 16 struct kvm_msr_filter { +#ifndef __KERNEL__ #define KVM_MSR_FILTER_DEFAULT_ALLOW (0 << 0) +#endif #define KVM_MSR_FILTER_DEFAULT_DENY (1 << 0) __u32 flags; struct kvm_msr_filter_range ranges[KVM_MSR_FILTER_MAX_RANGES];