Re: [Xen-devel] [V0 PATCH 1/6] AMD-PVH: construct vmcb changes

[Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>]

On Mon, 18 Aug 2014 20:59:00 -0400
Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:

> On 08/18/2014 07:46 PM, Mukesh Rathor wrote:
> > On Mon, 18 Aug 2014 11:10:54 +0200
> > Roger Pau Monnà <roger.pau@xxxxxxxxxx> wrote:
> >
> >> On 16/08/14 03:53, Mukesh Rathor wrote:
> >>> PVH guest starts in Long 64bit paging mode. This patch modifies
> >>> construct_vmcb for that.
> >>>
> >>> Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
> >>> ---
> >>>   xen/arch/x86/hvm/svm/vmcb.c | 18 +++++++++++++++---
> >>>   1 file changed, 15 insertions(+), 3 deletions(-)
> >>>
> >>> diff --git a/xen/arch/x86/hvm/svm/vmcb.c
> >>> b/xen/arch/x86/hvm/svm/vmcb.c index 21292bb..5df5f36 100644
> >>> --- a/xen/arch/x86/hvm/svm/vmcb.c
> >>> +++ b/xen/arch/x86/hvm/svm/vmcb.c
> >>> @@ -138,6 +138,8 @@ static int construct_vmcb(struct vcpu *v)
> >>>   
> >>>       /* Guest EFER. */
> >>>       v->arch.hvm_vcpu.guest_efer = 0;
> >>> +    if ( is_pvh_vcpu(v) )
> >>> +        v->arch.hvm_vcpu.guest_efer |= EFER_LMA;   /* PVH
> >>> 32bitfixme */ hvm_update_guest_efer(v);
> > ....
> >>
> >> I know this is already done on Intel in order to boot PVH guests,
> >> but now that we know what we need to modify in both Intel and AMD
> >> HVM code, do you think it would we suitable to add another
> >> parameter to vcpu_initialise in order to tell it to setup the vcpu
> >> to boot into long (or protected if we support 32bit PVH guests)
> >> mode (and prevent adding more is_pvh_vcpu)?
> > Well, we can defer adding parameter to vcpu_initialise to when 32bit
> > work gets done. For now, we could move common hvm fields
> > initialization to hvm_vcpu_initialise.. that way, we'd have fewer
> > is_pvh. I can submit a patch if Jan is ok with that.
> 
> Setting LMA bit for PVH guest is in fact already done by 
> hvm_vcpu_initialise()  so the change above is unnecessary.

yeah, that one we can leave out, but there still remains 

+    if ( is_pvh_vcpu(v) )
+        v->arch.hvm_vcpu.guest_cr[0] |= X86_CR0_PG;

and

+    v->arch.hvm_vcpu.guest_cr[4] = is_pvh_vcpu(v) ? X86_CR4_PAE : 0;

that could be moved to hvm_vcpu_initialise()

-Mukesh



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