aboutsummaryrefslogtreecommitdiff
path: root/bt-vhci.c
diff options
context:
space:
mode:
authorLaszlo Ersek <lersek@redhat.com>2015-06-19 04:40:14 +0200
committerMichael S. Tsirkin <mst@redhat.com>2015-06-23 22:57:49 +0200
commitd10dda2d60c8c225a89a53d53add799b69f6bb46 (patch)
tree29b537a75f19258269d7fb8c3c4446e90ba8fe0e /bt-vhci.c
parent4e5c9bfecf5da13e8e0f790002a55bb1cc0437b1 (diff)
hw/pci-bridge: disable SHPC in PXB
OVMF downloads the ACPI linker/loader script from QEMU when the edk2 PCI Bus driver globally signals the firmware that PCI enumeration and resource allocation have completed. At this point QEMU regenerates the ACPI payload in an fw_cfg read callback, and this is when the PXB's _CRS gets populated. Unfortunately, when this happens, the PCI_COMMAND_MEMORY bit is clear in the root bus's command register, *unlike* under SeaBIOS. The consequences unfold as follows: - When build_crs() fetches dev->io_regions[i].addr, it is all-bits-one, because pci_update_mappings() --> pci_bar_address() calculated it as PCI_BAR_UNMAPPED, due to the PCI_COMMAND_MEMORY bit being clear. - Consequently, the SHPC MMIO BAR (bar 0) of the bridge is not added to the _CRS, *despite* having been programmed in PCI config space. - Similarly, the SHPC MMIO BAR of the PXB is not removed from the main root bus's DWordMemory descriptor. - Guest OSes (Linux and Windows alike) notice the pre-programmed SHPC BAR within the PXB's config space, and notice that it conflicts with the main root bus's memory resource descriptors. Linux reports pci 0000:04:00.0: BAR 0: can't assign mem (size 0x100) pci 0000:04:00.0: BAR 0: trying firmware assignment [mem 0x88200000-0x882000ff 64bit] pci 0000:04:00.0: BAR 0: [mem 0x88200000-0x882000ff 64bit] conflicts with PCI Bus 0000:00 [mem 0x88200000-0xfebfffff] While Windows Server 2012 R2 reports https://technet.microsoft.com/en-us/library/cc732199%28v=ws.10%29.aspx This device cannot find enough free resources that it can use. If you want to use this device, you will need to disable one of the other devices on this system. (Code 12) This issue was apparently encountered earlier, see the "hack" in: https://lists.nongnu.org/archive/html/qemu-devel/2015-01/msg02983.html and the current hole-punching logic in build_crs() and build_ssdt() is probably supposed to remedy exactly that problem -- however, for OVMF they don't work, because at the end of the PCI enumeration and resource allocation, which cues the ACPI linker/loader client, the command register is clear. The "shpc" property of "pci-bridge", introduced in the previous patches, allows us to disable the standard hotplug controller cleanly, eliminating the SHPC bar and the conflict. Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Marcel Apfelbaum <marcel@redhat.com> Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'bt-vhci.c')
0 files changed, 0 insertions, 0 deletions