On Wed, Jun 20, 2012 at 10:23:06AM +0300, Pekka Enberg wrote:
> On Fri, 15 Jun 2012, Cyrill Gorcunov wrote:
>
> > On Fri, Jun 15, 2012 at 01:34:16PM +0200, Sasha Levin wrote:
> > > We need to set the HYPERVISOR flag to let the kernel know we're running
> > > under a hypervisor.
> > >
> > > This makes the kernel enable all sorts of para-virtualization options
> > > such as kvm-clock.
> > >
> > > Signed-off-by: Sasha Levin <[email protected]>
> >
> > OK, looks good, but please Sasha, add a comment into the code
> > itself about the bitflag enabled (or maybe Pekka would add at
> > merge time).
>
> Sasha?
I think it should be something like below
Cyrill
---
From: Sasha Levin <[email protected]>
Subject: [PATCH] kvm tools: set the HYPERVISOR flag in cpuid
We need to set the HYPERVISOR flag to let the kernel know we're running
under a hypervisor.
This makes the kernel enable all sorts of para-virtualization options
such as kvm-clock.
Signed-off-by: Sasha Levin <[email protected]>
[gorcunov@: Add comments on bits]
Signed-off-by: Cyrill Gorcunov <[email protected]>
---
tools/kvm/x86/cpuid.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
Index: linux-2.6.git/tools/kvm/x86/cpuid.c
===================================================================
--- linux-2.6.git.orig/tools/kvm/x86/cpuid.c
+++ linux-2.6.git/tools/kvm/x86/cpuid.c
@@ -21,8 +21,13 @@ static void filter_cpuid(struct kvm_cpui
struct kvm_cpuid_entry2 *entry = &kvm_cpuid->entries[i];
switch (entry->function) {
+ case 1:
+ /* Set X86_FEATURE_HYPERVISOR */
+ if (entry->index == 0)
+ entry->ecx |= (1 << 31);
+ break;
case 6:
- /* Clear presence of IA32_ENERGY_PERF_BIAS */
+ /* Clear X86_FEATURE_EPB */
entry->ecx = entry->ecx & ~(1 << 3);
break;
case CPUID_FUNC_PERFMON:
--
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