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Message-ID: <Y1Es7JWPNtcK2Qsu@kroah.com>
Date: Thu, 20 Oct 2022 13:11:40 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: wangwenmei168@....com
Cc: mathias.nyman@...el.com, linux-usb@...r.kernel.org,
linux-kernel@...r.kernel.org, gehao <gehao@...inos.cn>
Subject: Re: [RESEND PATCH] xhci: Fix Renesas PCIe controllers passthrough
issue
On Thu, Oct 20, 2022 at 06:39:14PM +0800, wangwenmei168@....com wrote:
> From: gehao <gehao@...inos.cn>
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@...inos.cn>
> ---
> 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
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