On 09/05/12 16:46, Michael S. Tsirkin wrote:
On Wed, May 09, 2012 at 03:24:52PM +0800, Amos Kong wrote:
Boot up a Linux VM with 8 pci block devices which are the 8 functions in one pci slot. | # qemu-kvm ... | -drive file=images/u0,if=none,id=drv0,format=qcow2,cache=none \ | -device virtio-blk-pci,drive=drv0,id=v0,multifunction=on,addr=0x03.0 \ | .... | -drive file=images/u7,if=none,id=drv7,format=qcow2,cache=none \ | -device virtio-blk-pci,drive=drv7,id=v7,multifunction=on,addr=0x03.7 \
Check devices in guest. | vm)# ls /dev/vd* | vda vdb vdc vde vdf vdg vdh | vm)# lspci |grep block | 00:03.0 SCSI storage controller: Red Hat, Inc Virtio block device | ... | 00:03.7 SCSI storage controller: Red Hat, Inc Virtio block device |
Func1~7 still exist in guest after hot-removing the whole slot through qemu monitor. | vm)# lspci |grep block (00:03.0 disappeared) | 00:03.1 SCSI storage controller: Red Hat, Inc Virtio block device (rev ff) | ... | 00:03.7 SCSI storage controller: Red Hat, Inc Virtio block device (rev ff) | vm)# ls /dev/vd* (vda disappeared) | vdb vdc vde vdf vdg vdh | vm)# mkfs /dev/vdb | INFO: task mkfs.ext2:1784 blocked for more than 120 seconds. (task hung)
Currently only func0 is defined in ACPI DSDT table of seabios, and only hot-adding func0 would cause a ACPI event for notification. Other funcs except func0 wouldn't be registered in linux pci driver. (we can only found func0 in slot->funcs list of pci driver).
Isn't this what your patch 'PCI: Can continually add funcs after adding func0' addresses?
This patch fixes the problem that some funcs could not be removed. the question is sending ACPI event for all functions (in same slot) or only function 0.
I found all funcs are defined in ACPI DSDT table in microsoft's example: http://www.microsoft.com/china/whdc/system/pnppwr/hotadd/hotplugpci.mspx#EUH
Is it a useful attestation ?
If yes it's commit f382a086f3129edc152b8044b69ccc6682e637bb in 3.4.
This commit fix the problem that some funcs could not be added.
So let's class the problematic behaviour guest bug and avoid workarounds in bios?