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pcie: Allow generic PCIe root port to specify link speed and width

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Allow users to experimentally specify speed and width values for the
generic PCIe root port.  Defaults remain at 2.5GT/s & x1 for
compatiblity with the intent to only support changing defaults via
machine types for now.

Note for libvirt testing that pcie-root-port controllers are given
default names like "pci.7" which don't play well with using the
"-set device.$name.$prop=$value" options accessible to us via
<qemu:commandline> options.  The solution is to add an <alias> to the
pcie-root-port <controller>, for example:

    <controller type='pci' index='7' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='7' port='0x15'/>
      <alias name='ua-gfx0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x5'/>
    </controller>

The "ua-" here is a mandatory prefix.  We can then use:

  <qemu:commandline>
    <qemu:arg value='-set'/>
    <qemu:arg value='device.ua-gfx0.x-speed=8'/>
    <qemu:arg value='-set'/>
    <qemu:arg value='device.ua-gfx0.x-width=16'/>
  </qemu:commandline>

or, without an alias, set globals such as:

  <qemu:commandline>
    <qemu:arg value='-global'/>
    <qemu:arg value='pcie-root-port.x-speed=8'/>
    <qemu:arg value='-global'/>
    <qemu:arg value='pcie-root-port.x-width=16'/>
  </qemu:commandline>

Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Tested-by: Geoffrey McRae <geoff@hostfission.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Alex Williamson 2018-12-12 12:39:43 -07:00 committed by Michael S. Tsirkin
parent 3d67447fe7
commit c2a490e344
1 changed files with 4 additions and 0 deletions
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4
hw/pci-bridge/gen_pcie_root_port.c
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@ -124,6 +124,10 @@ static Property gen_rp_props[] = {
res_reserve.mem_pref_32, -1),
DEFINE_PROP_SIZE("pref64-reserve", GenPCIERootPort,
res_reserve.mem_pref_64, -1),
DEFINE_PROP_PCIE_LINK_SPEED("x-speed", PCIESlot,
speed, PCIE_LINK_SPEED_2_5),
DEFINE_PROP_PCIE_LINK_WIDTH("x-width", PCIESlot,
width, PCIE_LINK_WIDTH_1),
DEFINE_PROP_END_OF_LIST()
};