Commit c8557f1b authored by Dr. David Alan Gilbert's avatar Dr. David Alan Gilbert Committed by Michael S. Tsirkin
Browse files

pcie_root_port: Disable ACS on older machines 



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: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20190730093719.12958-3-dgilbert@redhat.com>
Reviewed-by: default avatarJuan Quintela <quintela@redhat.com>
Reviewed-by: default avatarIgor Mammedov <imammedo@redhat.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent a58dfba2

hw/core/machine.c

+1 −0
Original line number Diff line number Diff line
@@ -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);