On Tue, 30 Jul 2019 10:37:19 +0100
"Dr. David Alan Gilbert (git)" <dgilb...@redhat.com> wrote:
> From: "Dr. David Alan Gilbert" <dgilb...@redhat.com>
>
> ACS got added in 4.0 unconditionally, that broke older<->4.0 migration
> where there was a PCIe root port.
> Fix this by turning it off for 3.1 and older machines; note this
> fixes compatibility for older QEMUs but breaks compatibility with 4.0
> for older machine types.
>
> machine type source qemu dest qemu
> 3.1 3.1 4.0 broken
> 3.1 3.1 4.1rc2 broken
> 3.1 3.1 4.1+this OK ++
> 3.1 4.0 4.1rc2 OK
> 3.1 4.0 4.1+this broken --
> 4.0 4.0 4.1rc2 OK
> 4.0 4.0 4.1+this OK
>
> So we gain and lose; the consensus seems to be treat this as a
> fix for older machine types.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
Reviewed-by: Igor Mammedov <imamm...@redhat.com>
> ---
> hw/core/machine.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index c58a8e594e..26a5f30e6d 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -52,6 +52,7 @@ GlobalProperty hw_compat_3_1[] = {
> { "virtio-blk-device", "discard", "false" },
> { "virtio-blk-device", "write-zeroes", "false" },
> { "virtio-balloon-device", "qemu-4-0-config-size", "false" },
> + { "pcie-root-port-base", "disable-acs", "true" }, /* Added in 4.1 */
> };
> const size_t hw_compat_3_1_len = G_N_ELEMENTS(hw_compat_3_1);
>
