On Fri, Jun 16, 2023, Yan Zhao wrote:
> diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
> index b35dd0bc9cad..688748e3a4d2 100644
> --- a/arch/x86/kvm/mtrr.c
> +++ b/arch/x86/kvm/mtrr.c
> @@ -25,6 +25,8 @@
> #define IA32_MTRR_DEF_TYPE_FE (1ULL << 10)
> #define IA32_MTRR_DEF_TYPE_TYPE_MASK (0xff)
>
> +static void kvm_mtrr_zap_gfn_range(struct kvm_vcpu *vcpu,
> + gfn_t gfn_start, gfn_t gfn_end);
> static bool is_mtrr_base_msr(unsigned int msr)
> {
> /* MTRR base MSRs use even numbers, masks use odd numbers. */
> @@ -341,7 +343,7 @@ static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr)
> var_mtrr_range(var_mtrr_msr_to_range(vcpu, msr), &start, &end);
> }
>
> - kvm_zap_gfn_range(vcpu->kvm, gpa_to_gfn(start), gpa_to_gfn(end));
> + kvm_mtrr_zap_gfn_range(vcpu, gpa_to_gfn(start), gpa_to_gfn(end));
> }
>
> static bool var_mtrr_range_is_valid(struct kvm_mtrr_range *range)
> @@ -437,6 +439,11 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
> void kvm_vcpu_mtrr_init(struct kvm_vcpu *vcpu)
> {
> INIT_LIST_HEAD(&vcpu->arch.mtrr_state.head);
> +
> + if (vcpu->vcpu_id == 0) {
Eww. This is actually unsafe, because kvm_arch_vcpu_create() is invoked without
holding kvm->lock. Oh, and vcpu_id is userspace controlled, so it's *very*
unsafe. Just initialize these in kvm_arch_init_vm().
> + spin_lock_init(&vcpu->kvm->arch.mtrr_zap_list_lock);
> + INIT_LIST_HEAD(&vcpu->kvm->arch.mtrr_zap_list);
> + }
> }
