On 10/14/2016 11:50 PM, Alex Williamson wrote:
On Fri, 14 Oct 2016 19:16:59 +0800 Cao jin <caoj.f...@cn.fujitsu.com> wrote:When vfio device is reset(encounter FLR, or bus reset), if need to do bus reset(vfio_pci_hot_reset_one is called), vfio_pci_pre_reset & vfio_pci_post_reset will be called twice. Signed-off-by: Cao jin <caoj.f...@cn.fujitsu.com> --- Also has a little question on vfio_pci_reset. it will be called when encounter bus reset, or FLR. The reset method's priority in this function now is: 1. If has "device specific reset function", then do it 2. If has FLR, then do it. 3. If it can do bus reset(only 1 affected device), then do it 4. If has pm_reset, then do it The question is: why pm reset has low priority than bus reset(if it does can do a bus reset)? why bus reset is not the last choice? In PCI driver of kernel, pls see __pci_dev_reset, we can see, if device support pm reset, it won't do bus reset.The PCI spec doesn't really define what sort of reset is done with a PM reset. My thinking was that if a device advertises an FLR capability then the hardware has made a concerted effort to have a per function reset mechanism available. NoSoftRst- is not terribly common and it's not entirely clear to me that the hardware has made a conscious effort to provide this for the purposes of per function reset mechanism. Therefore I've opt'd to prioritize a bus reset over a PM reset.
I see, thanks for your infomation. -- Yours Sincerely, Cao jin
