pci: reserve resources for pcie-pci-bridge to fix regressed hotplug on q35

If QEMU is started with unpopulated pcie-pci-bridge with ACPI PCI
hotplug enabled (default since QEMU-6.1), hotplugging a PCI device
into one of the bridge slots fails due to lack of resources.

once linux guest is booted (test used Fedora 34), hotplug NIC from
QEMU monitor:
  (qemu) device_add rtl8139,bus=pcie-pci-bridge-0,addr=0x2

guest fails hotplug with:
  pci 0000:01:02.0: [10ec:8139] type 00 class 0x020000
  pci 0000:01:02.0: reg 0x10: [io  0x0000-0x00ff]
  pci 0000:01:02.0: reg 0x14: [mem 0x00000000-0x000000ff]
  pci 0000:01:02.0: reg 0x30: [mem 0x00000000-0x0003ffff pref]
  pci 0000:01:02.0: BAR 6: no space for [mem size 0x00040000 pref]
  pci 0000:01:02.0: BAR 6: failed to assign [mem size 0x00040000 pref]
  pci 0000:01:02.0: BAR 0: no space for [io  size 0x0100]
  pci 0000:01:02.0: BAR 0: failed to assign [io  size 0x0100]
  pci 0000:01:02.0: BAR 1: no space for [mem size 0x00000100]
  pci 0000:01:02.0: BAR 1: failed to assign [mem size 0x00000100]
  8139cp: 8139cp: 10/100 PCI Ethernet driver v1.3 (Mar 22, 2004)
  PCI Interrupt Link [GSIG] enabled at IRQ 22
  8139cp 0000:01:02.0: no MMIO resource
  8139cp: probe of 0000:01:02.0 failed with error -5

Reason for this is that commit [1] didn't take into account
pcie-pci-bridge, marking bridge as non hotpluggable instead of
handling it as possibly SHPC capable bridge.
Fix issue by checking if pcie-pci-bridge is SHPC capable and
if it is mark it as hotpluggable.

Fixes regression in QEMU-6.1 and later, since it was switched
to ACPI based PCI hotplug on Q35 by default at that time.

RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=2001732
[1]
Fixes: 3aa31d7d63 ("hw/pci: reserve IO and mem for pci express downstream ports with no devices attached")
Signed-off-by: Igor Mammedov imammedo@redhat.com
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Laurent Vivier <lvivier@redhat.com>
CC: mapfelba@redhat.com
CC: kraxel@redhat.com
CC: mst@redhat.com
CC: lvivier@redhat.com
CC: jusual@redhat.com
This commit is contained in:
Igor Mammedov 2021-11-29 06:48:11 -05:00 committed by Kevin O'Connor
parent fa69276802
commit bba24ef84b
1 changed files with 5 additions and 0 deletions

View File

@ -802,6 +802,10 @@ static int pci_bus_hotplug_support(struct pci_bus *bus, u8 pcie_cap)
pcie_cap + PCI_EXP_FLAGS);
u8 port_type = ((pcie_flags & PCI_EXP_FLAGS_TYPE) >>
(__builtin_ffs(PCI_EXP_FLAGS_TYPE) - 1));
if (port_type == PCI_EXP_TYPE_PCI_BRIDGE)
goto check_shpc;
u8 downstream_port = (port_type == PCI_EXP_TYPE_DOWNSTREAM) ||
(port_type == PCI_EXP_TYPE_ROOT_PORT);
/*
@ -818,6 +822,7 @@ static int pci_bus_hotplug_support(struct pci_bus *bus, u8 pcie_cap)
return downstream_port && slot_implemented;
}
check_shpc:
shpc_cap = pci_find_capability(bus->bus_dev->bdf, PCI_CAP_ID_SHPC, 0);
return !!shpc_cap;
}