Re: [patch 04/10] KVM: MMU: mode specific sync_page

[Avi Kivity <avi@redhat.com>]

Marcelo Tosatti wrote:
> Examine guest pagetable and bring the shadow back in sync. Caller is responsible
> for local TLB flush before re-entering guest mode.
>
>   

Neat!  We had a gpte snapshot, and I forgot all about it.

> +	for (i = 0; i < PT64_ENT_PER_PAGE; i++) {
> +		if (is_shadow_present_pte(sp->spt[i])) {
>   

if (!is_..())
   continue;

to reduce indentation.

> +			pte_gpa += (i+offset) * sizeof(pt_element_t);
> +
> +			if (kvm_read_guest_atomic(vcpu->kvm, pte_gpa, &gpte,
> +						  sizeof(pt_element_t)))
> +				return -EINVAL;
>   

I guess we want a kvm_map_guest_page_atomic() to speed this up.  Can be 
done later as an optimization, of course.

> +
> +			if (gpte_to_gfn(gpte) != gfn || !(gpte & PT_ACCESSED_MASK)) {
> +				rmap_remove(vcpu->kvm, &sp->spt[i]);
> +				if (is_present_pte(gpte))
> +					sp->spt[i] = shadow_trap_nonpresent_pte;
> +				else
> +					sp->spt[i] = shadow_notrap_nonpresent_pte;
>   

set_shadow_pte()

> +				continue;
> +			}
> +
> +			if (!is_present_pte(gpte)) {
> +				rmap_remove(vcpu->kvm, &sp->spt[i]);
> +				sp->spt[i] = shadow_notrap_nonpresent_pte;
> +				continue;
> +			}
>   

Merge with previous block?

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.