On Thu, Aug 08, 2024, Selvarasu Ganesan wrote:
> This commit addresses an issue where the USB core could access an
> invalid event buffer address during runtime suspend, potentially causing
> SMMU faults and other memory issues. The problem arises from the
> following sequence.
> 1. In dwc3_gadget_suspend, there is a chance of a timeout when
> moving the USB core to the halt state after clearing the
> run/stop bit by software.
> 2. In dwc3_core_exit, the event buffer is cleared regardless of
> the USB core's status, which may lead to an SMMU faults and
This is a workaround to your specific setup behavior. Please document in
the commit message which platforms are impacted.
> other memory issues. if the USB core tries to access the event
> buffer address.
>
> To prevent this issue, this commit ensures that the event buffer address
> is not cleared by software when the USB core is active during runtime
> suspend by checking its status before clearing the buffer address.
>
> Cc: stable@xxxxxxxxxxxxxxx
We can keep the stable tag, but there's no issue with the commit below.
> Fixes: 89d7f9629946 ("usb: dwc3: core: Skip setting event buffers for host only controllers")
> Signed-off-by: Selvarasu Ganesan <selvarasu.g@xxxxxxxxxxx>
> ---
>
> Changes in v2:
> - Added separate check for USB controller status before cleaning the
> event buffer.
> - Link to v1: https://urldefense.com/v3/__https://lore.kernel.org/lkml/20240722145617.537-1-selvarasu.g@xxxxxxxxxxx/__;!!A4F2R9G_pg!cvZmnaxTWtJKR4ZDRZDa-8mvxpvkf5KPx57IwSXTSEtEFIVkPullR7sTYP0AM9de0xFbHLKdM_5jzBUiBL3f9SuioYE$
> ---
> drivers/usb/dwc3/core.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 734de2a8bd21..5b67d9bca71b 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -564,10 +564,15 @@ int dwc3_event_buffers_setup(struct dwc3 *dwc)
> void dwc3_event_buffers_cleanup(struct dwc3 *dwc)
> {
> struct dwc3_event_buffer *evt;
> + u32 reg;
>
> if (!dwc->ev_buf)
> return;
>
Please add comment here why we need this and which platform is impacted
should we need to go back and test.
> + reg = dwc3_readl(dwc->regs, DWC3_DSTS);
> + if (!(reg & DWC3_DSTS_DEVCTRLHLT))
> + return;
> +
> evt = dwc->ev_buf;
>
> evt->lpos = 0;
> --
> 2.17.1
>
Thanks,
Thinh
