This is a note to let you know that I've just added the patch titled
xen/scsiback: use lateeoi irq binding
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xen-scsiback-use-lateeoi-irq-binding.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue Nov 17 12:38:50 PM CET 2020
From: Juergen Gross <jgross@xxxxxxxx>
Date: Tue, 3 Nov 2020 15:29:05 +0100
Subject: xen/scsiback: use lateeoi irq binding
To: stable@xxxxxxxxxxxxxxx
Message-ID: <20201103142911.21980-9-jgross@xxxxxxxx>
From: Juergen Gross <jgross@xxxxxxxx>
commit 86991b6e7ea6c613b7692f65106076943449b6b7 upstream.
In order to reduce the chance for the system becoming unresponsive due
to event storms triggered by a misbehaving scsifront use the lateeoi
irq binding for scsiback and unmask the event channel only just before
leaving the event handling function.
In case of a ring protocol error don't issue an EOI in order to avoid
the possibility to use that for producing an event storm. This at once
will result in no further call of scsiback_irq_fn(), so the ring_error
struct member can be dropped and scsiback_do_cmd_fn() can signal the
protocol error via a negative return value.
This is part of XSA-332.
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Julien Grall <julien@xxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Wei Liu <wl@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/xen/xen-scsiback.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)
--- a/drivers/xen/xen-scsiback.c
+++ b/drivers/xen/xen-scsiback.c
@@ -91,7 +91,6 @@ struct vscsibk_info {
unsigned int irq;
struct vscsiif_back_ring ring;
- int ring_error;
spinlock_t ring_lock;
atomic_t nr_unreplied_reqs;
@@ -721,7 +720,8 @@ static struct vscsibk_pend *prepare_pend
return pending_req;
}
-static int scsiback_do_cmd_fn(struct vscsibk_info *info)
+static int scsiback_do_cmd_fn(struct vscsibk_info *info,
+ unsigned int *eoi_flags)
{
struct vscsiif_back_ring *ring = &info->ring;
struct vscsiif_request ring_req;
@@ -738,11 +738,12 @@ static int scsiback_do_cmd_fn(struct vsc
rc = ring->rsp_prod_pvt;
pr_warn("Dom%d provided bogus ring requests (%#x - %#x = %u). Halting ring processing\n",
info->domid, rp, rc, rp - rc);
- info->ring_error = 1;
- return 0;
+ return -EINVAL;
}
while ((rc != rp)) {
+ *eoi_flags &= ~XEN_EOI_FLAG_SPURIOUS;
+
if (RING_REQUEST_CONS_OVERFLOW(ring, rc))
break;
@@ -801,13 +802,16 @@ static int scsiback_do_cmd_fn(struct vsc
static irqreturn_t scsiback_irq_fn(int irq, void *dev_id)
{
struct vscsibk_info *info = dev_id;
+ int rc;
+ unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS;
- if (info->ring_error)
- return IRQ_HANDLED;
-
- while (scsiback_do_cmd_fn(info))
+ while ((rc = scsiback_do_cmd_fn(info, &eoi_flags)) > 0)
cond_resched();
+ /* In case of a ring error we keep the event channel masked. */
+ if (!rc)
+ xen_irq_lateeoi(irq, eoi_flags);
+
return IRQ_HANDLED;
}
@@ -828,7 +832,7 @@ static int scsiback_init_sring(struct vs
sring = (struct vscsiif_sring *)area;
BACK_RING_INIT(&info->ring, sring, PAGE_SIZE);
- err = bind_interdomain_evtchn_to_irq(info->domid, evtchn);
+ err = bind_interdomain_evtchn_to_irq_lateeoi(info->domid, evtchn);
if (err < 0)
goto unmap_page;
@@ -1251,7 +1255,6 @@ static int scsiback_probe(struct xenbus_
info->domid = dev->otherend_id;
spin_lock_init(&info->ring_lock);
- info->ring_error = 0;
atomic_set(&info->nr_unreplied_reqs, 0);
init_waitqueue_head(&info->waiting_to_free);
info->dev = dev;
Patches currently in stable-queue which might be from jgross@xxxxxxxx are
queue-4.14/xen-blkback-use-lateeoi-irq-binding.patch
queue-4.14/xen-events-block-rogue-events-for-some-time.patch
queue-4.14/xen-pvcallsback-use-lateeoi-irq-binding.patch
queue-4.14/xen-events-fix-race-in-evtchn_fifo_unmask.patch
queue-4.14/xen-events-switch-user-event-channels-to-lateeoi-model.patch
queue-4.14/xen-events-defer-eoi-in-case-of-excessive-number-of-events.patch
queue-4.14/xen-events-add-a-new-late-eoi-evtchn-framework.patch
queue-4.14/xen-events-use-a-common-cpu-hotplug-hook-for-event-channels.patch
queue-4.14/xen-events-avoid-removing-an-event-channel-while-handling-it.patch
queue-4.14/xen-netback-use-lateeoi-irq-binding.patch
queue-4.14/xen-pciback-use-lateeoi-irq-binding.patch
queue-4.14/xen-events-add-a-proper-barrier-to-2-level-uevent-unmasking.patch
queue-4.14/xen-scsiback-use-lateeoi-irq-binding.patch
