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Subject[PATCH v4 7/7] x86: KVM: svm: eliminate hardcoded RIP advancement from vmrun_interception()
Date
Just like we do with other intercepts, in vmrun_interception() we should be
doing kvm_skip_emulated_instruction() and not just RIP += 3. Also, it is
wrong to increment RIP before nested_svm_vmrun() as it can result in
kvm_inject_gp().

We can't call kvm_skip_emulated_instruction() after nested_svm_vmrun() so
move it inside.

Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/kvm/svm.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 51c39b608ef7..8473cbea7e8b 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3588,7 +3588,7 @@ static void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,

static int nested_svm_vmrun(struct vcpu_svm *svm)
{
- int rc;
+ int ret;
struct vmcb *nested_vmcb;
struct vmcb *hsave = svm->nested.hsave;
struct vmcb *vmcb = svm->vmcb;
@@ -3597,13 +3597,16 @@ static int nested_svm_vmrun(struct vcpu_svm *svm)

vmcb_gpa = svm->vmcb->save.rax;

- rc = kvm_vcpu_map(&svm->vcpu, gpa_to_gfn(vmcb_gpa), &map);
- if (rc) {
- if (rc == -EINVAL)
- kvm_inject_gp(&svm->vcpu, 0);
+ ret = kvm_vcpu_map(&svm->vcpu, gpa_to_gfn(vmcb_gpa), &map);
+ if (ret == EINVAL) {
+ kvm_inject_gp(&svm->vcpu, 0);
return 1;
+ } else if (ret) {
+ return kvm_skip_emulated_instruction(&svm->vcpu);
}

+ ret = kvm_skip_emulated_instruction(&svm->vcpu);
+
nested_vmcb = map.hva;

if (!nested_vmcb_checks(nested_vmcb)) {
@@ -3614,7 +3617,7 @@ static int nested_svm_vmrun(struct vcpu_svm *svm)

kvm_vcpu_unmap(&svm->vcpu, &map, true);

- return 1;
+ return ret;
}

trace_kvm_nested_vmrun(svm->vmcb->save.rip, vmcb_gpa,
@@ -3667,7 +3670,7 @@ static int nested_svm_vmrun(struct vcpu_svm *svm)
nested_svm_vmexit(svm);
}

- return 1;
+ return ret;
}

static void nested_svm_vmloadsave(struct vmcb *from_vmcb, struct vmcb *to_vmcb)
@@ -3743,9 +3746,6 @@ static int vmrun_interception(struct vcpu_svm *svm)
if (nested_svm_check_permissions(svm))
return 1;

- /* Save rip after vmrun instruction */
- kvm_rip_write(&svm->vcpu, kvm_rip_read(&svm->vcpu) + 3);
-
return nested_svm_vmrun(svm);
}

--
2.20.1
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