This is a note to let you know that I've just added the patch titled
KVM: x86: expose MSR_TSC_AUX to userspace
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-expose-msr_tsc_aux-to-userspace.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 9dbe6cf941a6fe82933aef565e4095fb10f65023 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Date: Thu, 12 Nov 2015 14:49:17 +0100
Subject: KVM: x86: expose MSR_TSC_AUX to userspace
From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/x86.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -951,7 +951,7 @@ static u32 msrs_to_save[] = {
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_FEATURE_CONTROL, MSR_IA32_BNDCFGS
+ MSR_IA32_FEATURE_CONTROL, MSR_IA32_BNDCFGS, MSR_TSC_AUX,
};
static unsigned num_msrs_to_save;
@@ -4006,16 +4006,17 @@ static void kvm_init_msr_list(void)
/*
* Even MSRs that are valid in the host may not be exposed
- * to the guests in some cases. We could work around this
- * in VMX with the generic MSR save/load machinery, but it
- * is not really worthwhile since it will really only
- * happen with nested virtualization.
+ * to the guests in some cases.
*/
switch (msrs_to_save[i]) {
case MSR_IA32_BNDCFGS:
if (!kvm_x86_ops->mpx_supported())
continue;
break;
+ case MSR_TSC_AUX:
+ if (!kvm_x86_ops->rdtscp_supported())
+ continue;
+ break;
default:
break;
}
Patches currently in stable-queue which might be from pbonzini@xxxxxxxxxx are
queue-4.4/kvm-x86-correctly-print-ac-in-traces.patch
queue-4.4/kvm-x86-expose-msr_tsc_aux-to-userspace.patch
queue-4.4/kvm-x86-fix-vmwrite-to-secondary_vm_exec_control.patch
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