Re: [PATCH] Improve the current FLR logic

[Yosuke Iwamatsu <y-iwamatsu@ab.jp.nec.com>]

Hi,

Cui, Dexuan wrote:
> [PATCH3] do_FLR_in_control_panel.patch:  the improved FLR logic in
> Control Panel: 1) If the device is PCIe endpoint and supports PCIe FLR,
> we use that; 2) Else, if the device is PCIe endpoint, and all functions
> on the device are assigned to the same guest, we use the immediate
> parent bus's Secondary Bus Reset to reset all functions of the device
> (here, actually we require all the functions of the device be assigned
> to the same guest); 3) Else, if the device is PCI endpoint and is on a
> host bus (e.g. integrated devices) and if the device supports PCI
> Advanced Capabilities, we use that for FLR; 4) Else, we use the
> Secondary Bus Reset (if the PCI device is behind a PCI/PCI-X bridge,
> then all devices behind the uppermost such PCI/PCI-X bridge above this
> device must be co-assigned)

In case 2) or 4), I think multfunction devices or sibling devices need
not be actually assigned to the same guest, if they are just owned by
pciback and not used by other guests.

> [PATCH4] list_assignable_devices.patch: a command "xm
> pci-list-assignable-devices" which can list all the assignable devices
> in the system. It is useful for end users.

It looks like xm_pci_list_assignable_devices() directly accesses to
sysfs and invokes hypercall without going through xend. Since xm
commands can be executed by a remote server through xmlrpc, most of
this function should be implemented in xend.
Also please note that test_assign_device() excludes the case of
non-iommu device assignment for pv.

Thanks,
-- Yosuke Iwamatsu