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[Qemu-devel] [PATCH v7 07/10] hw/pci-bridge: disable SHPC in PXB
From: |
Laszlo Ersek |
Subject: |
[Qemu-devel] [PATCH v7 07/10] hw/pci-bridge: disable SHPC in PXB |
Date: |
Fri, 19 Jun 2015 04:40:14 +0200 |
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 <address@hidden>
Cc: Marcel Apfelbaum <address@hidden>
Signed-off-by: Laszlo Ersek <address@hidden>
---
Notes:
v7:
- reference "shpc" property by macro PCI_BRIDGE_DEV_PROP_SHPC
v6:
- new in v6 (replaces "hw/pci-bridge: create interrupt-less,
hotplug-less bridge for PXB" from v5) [Michael]
hw/pci-bridge/pci_expander_bridge.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/hw/pci-bridge/pci_expander_bridge.c
b/hw/pci-bridge/pci_expander_bridge.c
index 3d840ef..70708ef 100644
--- a/hw/pci-bridge/pci_expander_bridge.c
+++ b/hw/pci-bridge/pci_expander_bridge.c
@@ -177,6 +177,7 @@ static int pxb_dev_initfn(PCIDevice *dev)
bds = qdev_create(BUS(bus), "pci-bridge");
bds->id = dev_name;
qdev_prop_set_uint8(bds, PCI_BRIDGE_DEV_PROP_CHASSIS_NR, pxb->bus_nr);
+ qdev_prop_set_bit(bds, PCI_BRIDGE_DEV_PROP_SHPC, false);
PCI_HOST_BRIDGE(ds)->bus = bus;
--
1.8.3.1
- [Qemu-devel] [PATCH v7 00/10] PXB changes, Laszlo Ersek, 2015/06/18
- [Qemu-devel] [PATCH v7 02/10] hw/pci-bridge: expose _test parameter in SHPC_VMSTATE(), Laszlo Ersek, 2015/06/18
- [Qemu-devel] [PATCH v7 01/10] migration: introduce VMSTATE_BUFFER_UNSAFE_INFO_TEST(), Laszlo Ersek, 2015/06/18
- [Qemu-devel] [PATCH v7 03/10] hw/pci-bridge: add macro for "chassis_nr" property, Laszlo Ersek, 2015/06/18
- [Qemu-devel] [PATCH v7 05/10] hw/pci: introduce shpc_present() helper function, Laszlo Ersek, 2015/06/18
- [Qemu-devel] [PATCH v7 04/10] hw/pci-bridge: add macro for "msi" property, Laszlo Ersek, 2015/06/18
- [Qemu-devel] [PATCH v7 06/10] hw/pci-bridge: introduce "shpc" property, Laszlo Ersek, 2015/06/18
- [Qemu-devel] [PATCH v7 07/10] hw/pci-bridge: disable SHPC in PXB,
Laszlo Ersek <=
- [Qemu-devel] [PATCH v7 08/10] hw/core: rebase sysbus_get_fw_dev_path() to g_strdup_printf(), Laszlo Ersek, 2015/06/18
- [Qemu-devel] [PATCH v7 09/10] hw/core: explicit OFW unit address callback for SysBusDeviceClass, Laszlo Ersek, 2015/06/18
- [Qemu-devel] [PATCH v7 10/10] hw/pci-bridge: format special OFW unit address for PXB host, Laszlo Ersek, 2015/06/18
- Re: [Qemu-devel] [PATCH v7 10/10] hw/pci-bridge: format special OFW unit address for PXB host, Kevin O'Connor, 2015/06/24