Re: [PATCH 2/2] KVM: SVM: Emulate next_rip svm feature

From: Avi Kivity
Date: Tue Jul 27 2010 - 14:32:48 EST


On 07/27/2010 07:14 PM, Joerg Roedel wrote:
This patch implements the emulations of the svm next_rip
feature in the nested svm implementation in kvm.

Signed-off-by: Joerg Roedel<joerg.roedel@xxxxxxx>
---
arch/x86/kvm/svm.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 7d10f2c..b44c9cc 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1919,6 +1919,7 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
nested_vmcb->control.exit_info_2 = vmcb->control.exit_info_2;
nested_vmcb->control.exit_int_info = vmcb->control.exit_int_info;
nested_vmcb->control.exit_int_info_err = vmcb->control.exit_int_info_err;
+ nested_vmcb->control.next_rip = vmcb->control.next_rip;


Can it be really this simple? Suppose we emulate a nested guest instruction just before vmexit, doesn't that invalidate vmcb->control.next_rip? Can that happen?

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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