On 15/04/2016 03:55, Yang Zhang wrote:
> The CPL check for XSETBV instruction is done by hardware on VMX.
> It only needs by SVM.
I don't think this is performance-sensitive, hence it's simpler to keep
the code as simple as possible. For example, if one added XSETBV
support to the emulator, your patch would introduce a bug.
Paolo
> Signed-off-by: Yang Zhang <yang.zhang.wz@xxxxxxxxx>
> ---
> arch/x86/kvm/svm.c | 4 +++-
> arch/x86/kvm/x86.c | 3 +--
> 2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 31346a3..14680f5 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -2715,7 +2715,9 @@ static int xsetbv_interception(struct vcpu_svm *svm)
> u64 new_bv = kvm_read_edx_eax(&svm->vcpu);
> u32 index = kvm_register_read(&svm->vcpu, VCPU_REGS_RCX);
>
> - if (kvm_set_xcr(&svm->vcpu, index, new_bv) == 0) {
> + if (svm_get_cpl(&svm->vcpu) != 0)
> + kvm_inject_gp(&svm->vcpu, 0);
> + else if (kvm_set_xcr(&svm->vcpu, index, new_bv) == 0) {
> svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
> skip_emulated_instruction(&svm->vcpu);
> }
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 8f57335..3cfc59f 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -709,8 +709,7 @@ static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32
> index, u64 xcr)
>
> int kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
> {
> - if (kvm_x86_ops->get_cpl(vcpu) != 0 ||
> - __kvm_set_xcr(vcpu, index, xcr)) {
> + if (__kvm_set_xcr(vcpu, index, xcr)) {
> kvm_inject_gp(vcpu, 0);
> return 1;
> }
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