On Thu, Aug 29, 2013 at 12:00:53AM +0200, Alexander Graf wrote:
>
> On 06.08.2013, at 06:16, Paul Mackerras wrote:
>
> > kvm_start_lightweight:
> > + /* Copy registers into shadow vcpu so we can access them in real mode */
> > + GET_SHADOW_VCPU(r3)
> > + bl FUNC(kvmppc_copy_to_svcpu)
>
> This will clobber r3 and r4, no? We need to restore them from the stack here
> I would think.
You're right. We don't need to restore r3 since we don't actually use
it, but we do need to restore r4.
> > #ifdef CONFIG_PPC_BOOK3S_32
> > /* We set segments as unused segments when invalidating them. So
> > * treat the respective fault as segment fault. */
> > - if (svcpu->sr[kvmppc_get_pc(vcpu) >> SID_SHIFT] == SR_INVALID) {
> > - kvmppc_mmu_map_segment(vcpu, kvmppc_get_pc(vcpu));
> > - r = RESUME_GUEST;
> > + {
> > + struct kvmppc_book3s_shadow_vcpu *svcpu;
> > + u32 sr;
> > +
> > + svcpu = svcpu_get(vcpu);
> > + sr = svcpu->sr[kvmppc_get_pc(vcpu) >> SID_SHIFT];
>
> Doesn't this break two concurrently running guests now that we don't copy the
> shadow vcpu anymore? Just move the sr array to a kmalloc'ed area until the
> whole vcpu is kmalloc'ed. Then you can get rid of all shadow vcpu code.
This is 32-bit only... the svcpu is already kmalloc'ed, so I'm not
sure what you're asking for here or why you think this would break
with multiple guests.
Paul.
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