* Michael S. Tsirkin (mst@xxxxxxxxxx) wrote:
> KVM does not virtualize low address bits for memory accesses, so we must
> require that PCI BAR size is a multiple of 4K for passthrough to work
> (this also guarantees that address is 4K aligned).
>
> Users of recent linux kernels can force resource size up to 4K
> using:
>
> commit 32a9a682bef2f6fce7026bd94d1ce20028b0e52d
> Author: Yuji Shimada <shimada-yxb@xxxxxxxxxxxxxxx>
> Date: Mon Mar 16 17:13:39 2009 +0900
> PCI: allow assignment of memory resources with a specified alignment
>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
>
> ---
>
> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
> index 237060f..c2ef31f 100644
> --- a/hw/device-assignment.c
> +++ b/hw/device-assignment.c
> @@ -381,6 +381,14 @@ static int assigned_dev_register_regions(PCIRegion *io_regions,
> int t = cur_region->type & IORESOURCE_PREFETCH
> ? PCI_ADDRESS_SPACE_MEM_PREFETCH
> : PCI_ADDRESS_SPACE_MEM;
> + if (cur_region->size & 0xFFF) {
> + fprintf(stderr, "Unable to assign device: PCI region %d "
> + "at address 0x%llx has size 0x%x, "
> + " which is not a multiple of 4K\n",
> + i, (unsigned long long)cur_region->base_addr,
> + cur_region->size);
> + return -1;
> + }
should render this useless now shouldn't it?
/* add offset */
pci_dev->v_addrs[i].u.r_virtbase +=
(cur_region->base_addr & 0xFFF);
thanks,
-chris
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