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Subject[PATCH 3.2 05/87] KVM: x86: expose MSR_TSC_AUX to userspace
3.2.77-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Paolo Bonzini <pbonzini@redhat.com>

commit 9dbe6cf941a6fe82933aef565e4095fb10f65023 upstream.

If we do not do this, it is not properly saved and restored across
migration. Windows notices due to its self-protection mechanisms,
and is very upset about it (blue screen of death).

Cc: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[bwh: Backported to 3.2:
- We didn't yet have the switch() in kvm_init_msr_list as MPX is not
supported at all
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -834,7 +834,8 @@ static u32 msrs_to_save[] = {
#ifdef CONFIG_X86_64
MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR,
#endif
- MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA
+ MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
+ MSR_TSC_AUX,
};

static unsigned num_msrs_to_save;
@@ -3867,6 +3868,20 @@ static void kvm_init_msr_list(void)
for (i = j = KVM_SAVE_MSRS_BEGIN; i < ARRAY_SIZE(msrs_to_save); i++) {
if (rdmsr_safe(msrs_to_save[i], &dummy[0], &dummy[1]) < 0)
continue;
+
+ /*
+ * Even MSRs that are valid in the host may not be exposed
+ * to the guests in some cases.
+ */
+ switch (msrs_to_save[i]) {
+ case MSR_TSC_AUX:
+ if (!kvm_x86_ops->rdtscp_supported())
+ continue;
+ break;
+ default:
+ break;
+ }
+
if (j < i)
msrs_to_save[j] = msrs_to_save[i];
j++;
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