Re: [PATCH] Fix sysenter migration issue on AMD CPUs

[Andre Przywara <andre.przywara@amd.com>]

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Thomas Besser wrote:
> Andre Przywara wrote:
>> Stephane, Thomas: Can you verify this?
> 
> I'm not very familiar with compiling kvm-mod from git sources. And your
> patch does not apply to svm.c shipped with kernel 2.6.30.5
You shouldn't have seen any problems with 2.6.30.5, since the code in 
question (sysenter/syscall emulation) is not in here.

> 
> So at the moment I have no clue, how to verify. Is there any short howto out
> there, how to get kvm module from git source?
You can use the attached patch, which applies against 
kvm-kmod-devel-88.tar.gz

If that does not help, tell me with what tree or tarball you are usually 
generating the KVM kernel modules. I use Avi's latest git tree, which is 
regularly synced with 2.6.31.rc<x>. The patch from Friday should apply 
against this one.
$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/avi/kvm.git
You will have to build your whole kernel with this tree, if you build 
only the modules from here they will certainly mismatch your running kernel.

Regards,
Andre.

-- 
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 448 3567 12
----to satisfy European Law for business letters:
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Registergericht Muenchen, HRB Nr. 43632

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diff --git a/x86/svm.c b/x86/svm.c
index fb29061..75d18bf 100644
--- a/x86/svm.c
+++ b/x86/svm.c
@@ -117,7 +117,6 @@ struct vcpu_svm {
 	unsigned long vmcb_pa;
 	struct svm_cpu_data *svm_data;
 	uint64_t asid_generation;
-	uint64_t sysenter_cs;
 	uint64_t sysenter_esp;
 	uint64_t sysenter_eip;
 
@@ -436,8 +435,6 @@ static void svm_vcpu_init_msrpm(u32 *msrpm)
 #endif
 	set_msr_interception(msrpm, MSR_K6_STAR, 1, 1);
 	set_msr_interception(msrpm, MSR_IA32_SYSENTER_CS, 1, 1);
-	set_msr_interception(msrpm, MSR_IA32_SYSENTER_ESP, 1, 1);
-	set_msr_interception(msrpm, MSR_IA32_SYSENTER_EIP, 1, 1);
 }
 
 static void svm_enable_lbrv(struct vcpu_svm *svm)
@@ -2062,7 +2059,7 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 *data)
 		break;
 #endif
 	case MSR_IA32_SYSENTER_CS:
-		*data = svm->sysenter_cs;
+		*data = svm->vmcb->save.sysenter_cs;
 		break;
 	case MSR_IA32_SYSENTER_EIP:
 		*data = svm->sysenter_eip;
@@ -2151,13 +2148,15 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 data)
 		break;
 #endif
 	case MSR_IA32_SYSENTER_CS:
-		svm->sysenter_cs = data;
+		svm->vmcb->save.sysenter_cs = data;
 		break;
 	case MSR_IA32_SYSENTER_EIP:
 		svm->sysenter_eip = data;
+		svm->vmcb->save.sysenter_eip = data;
 		break;
 	case MSR_IA32_SYSENTER_ESP:
 		svm->sysenter_esp = data;
+		svm->vmcb->save.sysenter_esp = data;
 		break;
 	case MSR_IA32_DEBUGCTLMSR:
 		if (!svm_has(SVM_FEATURE_LBRV)) {