On 2016/4/15 18:11, Paolo Bonzini wrote:
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.
In what case we need to decode XSETBV?
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;
}
--
best regards
yang
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