pcie: check that slt ctrl changed before deleting

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

View file

@ -107,7 +107,8 @@ void pcie_cap_lnkctl_reset(PCIDevice *dev);
void pcie_cap_slot_init(PCIDevice *dev, uint16_t slot);
void pcie_cap_slot_reset(PCIDevice *dev);
void pcie_cap_slot_write_config(PCIDevice *dev,
void pcie_cap_slot_get(PCIDevice *dev, uint16_t *slot_ctl, uint16_t *slt_sta);
void pcie_cap_slot_write_config(PCIDevice *dev, uint16_t slot_ctl, uint16_t slt_sta,
uint32_t addr, uint32_t val, int len);
int pcie_cap_slot_post_load(void *opaque, int version_id);
void pcie_cap_slot_push_attention_button(PCIDevice *dev);