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SubjectRe: [PATCH] kvm mmu: reduce 50% memory usage
On 04/29/2010 09:09 PM, Marcelo Tosatti wrote:
>
> You missed quadrant on 4mb large page emulation with shadow (see updated
> patch below).

Good catch.

> Also for some reason i can't understand the assumption
> does not hold for large sptes with TDP, so reverted for now.
>

It's unrelated to TDP, same issue with shadow. I think the calculation
is correct. For example the 4th spte for a level=2 page will yield
gfn=4*512.

> @@ -393,6 +393,27 @@ static void mmu_free_rmap_desc(struct kvm_rmap_desc *rd)
> kfree(rd);
> }
>
> +static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index)
> +{
> + gfn_t gfn;
> +
> + if (!sp->role.direct)
> + return sp->gfns[index];
> +
> + gfn = sp->gfn + index * (1<< (sp->role.level - 1) * PT64_LEVEL_BITS);
> + gfn += sp->role.quadrant<< PT64_LEVEL_BITS;
>

PT64_LEVEL_BITS * level

> +
> + return gfn;
> +}
> +
>
>


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



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