On Mon, Aug 05, 2013 at 08:03:31AM -0400, Paolo Bonzini wrote:
>
>
> ----- Original Message -----
> > From: "Arthur Chunqi Li" <[email protected]>
> > To: [email protected]
> > Cc: "jan kiszka" <[email protected]>, [email protected], [email protected],
> > "Arthur Chunqi Li" <[email protected]>
> > Sent: Monday, August 5, 2013 1:18:13 PM
> > Subject: [PATCH v2] KVM: nVMX: Advertise IA32_PAT in VM exit control
> >
> > Advertise VM_EXIT_SAVE_IA32_PAT and VM_EXIT_LOAD_IA32_PAT.
> >
> > Signed-off-by: Arthur Chunqi Li <[email protected]>
> > ---
> >
> > ChangeLog to v1:
> > Add host features check. Format is the same as "entry controls".
> >
> > arch/x86/kvm/vmx.c | 10 ++++++----
> > 1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> > index 396572d..fd451c1 100644
> > --- a/arch/x86/kvm/vmx.c
> > +++ b/arch/x86/kvm/vmx.c
> > @@ -2191,14 +2191,16 @@ static __init void nested_vmx_setup_ctls_msrs(void)
> > * If bit 55 of VMX_BASIC is off, bits 0-8 and 10, 11, 13, 14, 16 and
> > * 17 must be 1.
> > */
> > + rdmsr(MSR_IA32_VMX_EXIT_CTLS,
> > + nested_vmx_exit_ctls_low, nested_vmx_exit_ctls_high);
> > nested_vmx_exit_ctls_low = VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR;
> > + nested_vmx_exit_ctls_high &=
> > + VM_EXIT_LOAD_IA32_PAT | VM_EXIT_SAVE_IA32_PAT;
> > + nested_vmx_exit_ctls_high |= VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR;
> > /* Note that guest use of VM_EXIT_ACK_INTR_ON_EXIT is not supported. */
> > #ifdef CONFIG_X86_64
> > - nested_vmx_exit_ctls_high = VM_EXIT_HOST_ADDR_SPACE_SIZE;
> > -#else
> > - nested_vmx_exit_ctls_high = 0;
> > + nested_vmx_exit_ctls_high |= VM_EXIT_HOST_ADDR_SPACE_SIZE;
>
> I think you should clear the bit if !X86_64 (and not do anything if
> X86_64, the bit should be already set in MSR_IA32_VMX_EXIT_CTLS).
>
Yes, we do not support 64 bit guests on 32bit host. It means that 32 bit
host is essentially "processors that do not support Intel 64 architecture",
so the control should be zero.
--
Gleb.
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