On Thu, Oct 20, 2022 at 06:39:14PM +0800, wangwenmei168@xxxxxxx wrote: > From: gehao <gehao@xxxxxxxxxx> This does not match your from: line in the email at all, so we can't take this :( Please work with your company's email system to make it possible to send kernel patches if you wish to be able to contribute. > > When we use uPD720201 USB 3.0 Host Controller passthrough to VM > guest os will report follow errors and it can not working. > > xhci_hcd 0000:09:00.0: Host took too long to start, waited 16000 > microseconds. > xhci_hcd 0000:09:00.0: startup error -19. > > Because when we passthroug some device to our guest os, > dev->iommu_group =NULL,so it will return from this function, > Actually it still control by host os. > I think that this condition is not necessary. > > For host os with IOMMU,it is safe. > For host os with noiommu,doing anything when there is no > iommu is definitely. > For guest os,the addresses we can access are restricted. > > After add this path,they all work well. This line isn't needed in a changelog, right? > > Signed-off-by: gehao <gehao@xxxxxxxxxx> > --- > drivers/usb/host/xhci.c | 6 +----- > 1 file changed, 1 insertion(+), 5 deletions(-) > > diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c > index 5176765c4013..e8f4c4ee3ea3 100644 > --- a/drivers/usb/host/xhci.c > +++ b/drivers/usb/host/xhci.c > @@ -241,12 +241,8 @@ static void xhci_zero_64b_regs(struct xhci_hcd *xhci) > * changing the programming leads to extra accesses even if the > * controller is supposed to be halted. The controller ends up with > * a fatal fault, and is then ripe for being properly reset. > - * > - * Special care is taken to only apply this if the device is behind > - * an iommu. Doing anything when there is no iommu is definitely > - * unsafe... How many different systems did you test this on to verify that this is now ok to do? thanks, greg k-h
