Re: [Xen-devel] [v3][PATCH 1/1] xen:vtd: missing RMRR mapping while share EPT

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.07.14 at 08:47, <tiejun.chen@xxxxxxxxx> wrote:
>>  So I think it would be prudent to at least try to detect a clash here
>> and return an error.
> 
> Could we check if this pte already present like this?
> 
> @@ -1870,6 +1872,16 @@ static int rmrr_identity_mapping(struct domain *d,
>           if ( iommu_use_hap_pt(d) )
>           {
>               ASSERT(!iommu_passthrough || !is_hardware_domain(d));
> +            /* get last level pte */
> +            pg_maddr = addr_to_dma_page_maddr(d, ((paddr_t)gfn << 
> PAGE_SHIFT_4K), 0);
> +            page = (struct dma_pte *)map_vtd_domain_page(pg_maddr);
> +            pte = page + address_level_offset(addr, 1);
> +            if ( dma_pte_present(*pte) )
> +            {
> +                printk(XENLOG_ERR VTDPREFIX
> +                       "Overlapping RMRRs at %"PRIx64".\n", 
> (paddr_t)base_gfn);
> +                return -1;
> +            }
>               if ( set_mmio_p2m_entry(d, base_pfn, _mfn(base_pfn)) )
>                   return -1;
>           }

I think you'd be better off using P2M functions here, even more so
considering that you're in an iommu_use_hap_pt() guarded code
section.

Jan


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