2023-09-22 12:50:23

by Prashanth K

Subject: [PATCH] xhci: Keep interrupt disabled in initialization until host is running.

From: Hongyu Xie <[email protected]>

[ Upstream commit 808925075fb750804a60ff0710614466c396db4 ]

irq is disabled in xhci_quiesce(called by xhci_halt, with bit:2 cleared
in USBCMD register), but xhci_run(called by usb_add_hcd) re-enable it.
It's possible that you will receive thousands of interrupt requests
after initialization for 2.0 roothub. And you will get a lot of
warning like, "xHCI dying, ignoring interrupt. Shouldn't IRQs be
disabled?". This amount of interrupt requests will cause the entire
system to freeze.
This problem was first found on a device with ASM2142 host controller
on it.

[tidy up old code while moving it, reword header -Mathias]

Cc: [email protected]
Signed-off-by: Hongyu Xie <[email protected]>
Signed-off-by: Mathias Nyman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/usb/host/xhci.c | 34 +++++++++++++++++++++-------------
1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 541fe4d..7ee747e 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -607,8 +607,27 @@ static int xhci_init(struct usb_hcd *hcd)

static int xhci_run_finished(struct xhci_hcd *xhci)
{
+ unsigned long flags;
+ u32 temp;
+
+ /*
+ * Enable interrupts before starting the host (xhci 4.2 and 5.5.2).
+ * Protect the short window before host is running with a lock
+ */
+ spin_lock_irqsave(&xhci->lock, flags);
+
+ xhci_dbg_trace(xhci, trace_xhci_dbg_init, "Enable interrupts");
+ temp = readl(&xhci->op_regs->command);
+ temp |= (CMD_EIE);
+ writel(temp, &xhci->op_regs->command);
+
+ xhci_dbg_trace(xhci, trace_xhci_dbg_init, "Enable primary interrupter");
+ temp = readl(&xhci->ir_set->irq_pending);
+ writel(ER_IRQ_ENABLE(temp), &xhci->ir_set->irq_pending);
+
if (xhci_start(xhci)) {
xhci_halt(xhci);
+ spin_unlock_irqrestore(&xhci->lock, flags);
return -ENODEV;
}
xhci->shared_hcd->state = HC_STATE_RUNNING;
@@ -619,6 +638,8 @@ static int xhci_run_finished(struct xhci_hcd *xhci)

xhci_dbg_trace(xhci, trace_xhci_dbg_init,
"Finished xhci_run for USB3 roothub");
+
+ spin_unlock_irqrestore(&xhci->lock, flags);
return 0;
}

@@ -667,19 +688,6 @@ int xhci_run(struct usb_hcd *hcd)
temp |= (xhci->imod_interval / 250) & ER_IRQ_INTERVAL_MASK;
writel(temp, &xhci->ir_set->irq_control);

- /* Set the HCD state before we enable the irqs */
- temp = readl(&xhci->op_regs->command);
- temp |= (CMD_EIE);
- xhci_dbg_trace(xhci, trace_xhci_dbg_init,
- "// Enable interrupts, cmd = 0x%x.", temp);
- writel(temp, &xhci->op_regs->command);
-
- temp = readl(&xhci->ir_set->irq_pending);
- xhci_dbg_trace(xhci, trace_xhci_dbg_init,
- "// Enabling event ring interrupter %p by writing 0x%x to irq_pending",
- xhci->ir_set, (unsigned int) ER_IRQ_ENABLE(temp));
- writel(ER_IRQ_ENABLE(temp), &xhci->ir_set->irq_pending);
-
if (xhci->quirks & XHCI_NEC_HOST) {
struct xhci_command *command;

--
2.7.4

2023-09-22 14:16:47

by Greg Kroah-Hartman

Subject: Re: [PATCH] xhci: Keep interrupt disabled in initialization until host is running.

On Fri, Sep 22, 2023 at 04:03:26PM +0530, Prashanth K wrote:
>
>
> On 22-09-23 04:00 pm, Greg Kroah-Hartman wrote:
> > On Fri, Sep 22, 2023 at 02:51:41PM +0530, Prashanth K wrote:
> > > From: Hongyu Xie <[email protected]>
> > >
> > > [ Upstream commit 808925075fb750804a60ff0710614466c396db4 ]
> > >
> > > irq is disabled in xhci_quiesce(called by xhci_halt, with bit:2 cleared
> > > in USBCMD register), but xhci_run(called by usb_add_hcd) re-enable it.
> > > It's possible that you will receive thousands of interrupt requests
> > > after initialization for 2.0 roothub. And you will get a lot of
> > > warning like, "xHCI dying, ignoring interrupt. Shouldn't IRQs be
> > > disabled?". This amount of interrupt requests will cause the entire
> > > system to freeze.
> > > This problem was first found on a device with ASM2142 host controller
> > > on it.
> > >
> > > [tidy up old code while moving it, reword header -Mathias]
> > >
> > > Cc: [email protected]
> > > Signed-off-by: Hongyu Xie <[email protected]>
> > > Signed-off-by: Mathias Nyman <[email protected]>
> > > Link: https://lore.kernel.org/r/[email protected]
> > > Signed-off-by: Greg Kroah-Hartman <[email protected]>
> > > ---
> > > drivers/usb/host/xhci.c | 34 +++++++++++++++++++++-------------
> > > 1 file changed, 21 insertions(+), 13 deletions(-)
> >
> > What stable kernel(s) are you asking this to be applied to?
> >
> > greg k-h
> Need this patch on v5.15, I had cc'ed "[email protected] # 5.15", but looks
> like it didn't work. Should I resend this with SOB and CC tags?

Yes please.

thanks,

greg k-h