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pcie: check that slt ctrl changed before deleting

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During boot, linux would sometimes overwrites control of a powered off
slot before powering it on. Unfortunately QEMU interprets that as a
power off request and ejects the device.

For example:

/x86_64-softmmu/qemu-system-x86_64 -enable-kvm -S -machine q35  \
    -device pcie-root-port,id=pcie_root_port_0,slot=2,chassis=2,addr=0x2,bus=pcie.0 \
    -monitor stdio disk.qcow2
(qemu)device_add virtio-balloon-pci,id=balloon,bus=pcie_root_port_0
(qemu)cont

Balloon is deleted during guest boot.

To fix, save control beforehand and check that power
or led state actually change before ejecting.

Note: this is more a hack than a solution, ideally we'd
find a better way to detect ejects, or move away
from ejects completely and instead monitor whether
it's safe to delete device due to e.g. its power state.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Tested-by: Igor Mammedov <imammedo@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2019-06-21 00:12:22 -04:00
parent 861dc73518
commit 2841ab435b
4 changed files with 22 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

14
hw/pci/pcie.c
View file

@ -594,7 +594,15 @@ void pcie_cap_slot_reset(PCIDevice *dev)
hotplug_event_update_event_status(dev);
}
void pcie_cap_slot_write_config(PCIDevice *dev,
void pcie_cap_slot_get(PCIDevice *dev, uint16_t *slt_ctl, uint16_t *slt_sta)
{
uint32_t pos = dev->exp.exp_cap;
uint8_t *exp_cap = dev->config + pos;
*slt_ctl = pci_get_word(exp_cap + PCI_EXP_SLTCTL);
*slt_sta = pci_get_word(exp_cap + PCI_EXP_SLTSTA);
}
void pcie_cap_slot_write_config(PCIDevice *dev, uint16_t slt_ctl, uint16_t slt_sta,
uint32_t addr, uint32_t val, int len)
{
uint32_t pos = dev->exp.exp_cap;
@ -623,7 +631,9 @@ void pcie_cap_slot_write_config(PCIDevice *dev,
* controller is off, it is safe to detach the devices.
*/
if ((sltsta & PCI_EXP_SLTSTA_PDS) && (val & PCI_EXP_SLTCTL_PCC) &&
((val & PCI_EXP_SLTCTL_PIC_OFF) == PCI_EXP_SLTCTL_PIC_OFF)) {
(val & PCI_EXP_SLTCTL_PIC_OFF) == PCI_EXP_SLTCTL_PIC_OFF &&
(!(slt_ctl & PCI_EXP_SLTCTL_PCC) ||
(slt_ctl & PCI_EXP_SLTCTL_PIC_OFF) != PCI_EXP_SLTCTL_PIC_OFF)) {
PCIBus *sec_bus = pci_bridge_get_sec_bus(PCI_BRIDGE(dev));
pci_for_each_device(sec_bus, pci_bus_num(sec_bus),
pcie_unplug_device, NULL);