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