From: Greg Kroah-Hartman Date: Tue, 29 Apr 2025 07:41:11 +0000 (+0200) Subject: 5.10-stable patches X-Git-Tag: v5.4.293~38 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=1f8ae534f006c46575b766b43d80f8daf59e0ff5;p=thirdparty%2Fkernel%2Fstable-queue.git 5.10-stable patches added patches: s390-virtio_ccw-don-t-allocate-assign-airqs-for-non-existing-queues.patch --- diff --git a/queue-5.10/s390-virtio_ccw-don-t-allocate-assign-airqs-for-non-existing-queues.patch b/queue-5.10/s390-virtio_ccw-don-t-allocate-assign-airqs-for-non-existing-queues.patch new file mode 100644 index 0000000000..33e68ef2f7 --- /dev/null +++ b/queue-5.10/s390-virtio_ccw-don-t-allocate-assign-airqs-for-non-existing-queues.patch @@ -0,0 +1,141 @@ +From 2ccd42b959aaf490333dbd3b9b102eaf295c036a Mon Sep 17 00:00:00 2001 +From: David Hildenbrand +Date: Wed, 2 Apr 2025 22:36:21 +0200 +Subject: s390/virtio_ccw: Don't allocate/assign airqs for non-existing queues + +From: David Hildenbrand + +commit 2ccd42b959aaf490333dbd3b9b102eaf295c036a upstream. + +If we finds a vq without a name in our input array in +virtio_ccw_find_vqs(), we treat it as "non-existing" and set the vq pointer +to NULL; we will not call virtio_ccw_setup_vq() to allocate/setup a vq. + +Consequently, we create only a queue if it actually exists (name != NULL) +and assign an incremental queue index to each such existing queue. + +However, in virtio_ccw_register_adapter_ind()->get_airq_indicator() we +will not ignore these "non-existing queues", but instead assign an airq +indicator to them. + +Besides never releasing them in virtio_ccw_drop_indicators() (because +there is no virtqueue), the bigger issue seems to be that there will be a +disagreement between the device and the Linux guest about the airq +indicator to be used for notifying a queue, because the indicator bit +for adapter I/O interrupt is derived from the queue index. + +The virtio spec states under "Setting Up Two-Stage Queue Indicators": + + ... indicator contains the guest address of an area wherein the + indicators for the devices are contained, starting at bit_nr, one + bit per virtqueue of the device. + +And further in "Notification via Adapter I/O Interrupts": + + For notifying the driver of virtqueue buffers, the device sets the + bit in the guest-provided indicator area at the corresponding + offset. + +For example, QEMU uses in virtio_ccw_notify() the queue index (passed as +"vector") to select the relevant indicator bit. If a queue does not exist, +it does not have a corresponding indicator bit assigned, because it +effectively doesn't have a queue index. + +Using a virtio-balloon-ccw device under QEMU with free-page-hinting +disabled ("free-page-hint=off") but free-page-reporting enabled +("free-page-reporting=on") will result in free page reporting +not working as expected: in the virtio_balloon driver, we'll be stuck +forever in virtballoon_free_page_report()->wait_event(), because the +waitqueue will not be woken up as the notification from the device is +lost: it would use the wrong indicator bit. + +Free page reporting stops working and we get splats (when configured to +detect hung wqs) like: + + INFO: task kworker/1:3:463 blocked for more than 61 seconds. + Not tainted 6.14.0 #4 + "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. + task:kworker/1:3 [...] + Workqueue: events page_reporting_process + Call Trace: + [<000002f404e6dfb2>] __schedule+0x402/0x1640 + [<000002f404e6f22e>] schedule+0x3e/0xe0 + [<000002f3846a88fa>] virtballoon_free_page_report+0xaa/0x110 [virtio_balloon] + [<000002f40435c8a4>] page_reporting_process+0x2e4/0x740 + [<000002f403fd3ee2>] process_one_work+0x1c2/0x400 + [<000002f403fd4b96>] worker_thread+0x296/0x420 + [<000002f403fe10b4>] kthread+0x124/0x290 + [<000002f403f4e0dc>] __ret_from_fork+0x3c/0x60 + [<000002f404e77272>] ret_from_fork+0xa/0x38 + +There was recently a discussion [1] whether the "holes" should be +treated differently again, effectively assigning also non-existing +queues a queue index: that should also fix the issue, but requires other +workarounds to not break existing setups. + +Let's fix it without affecting existing setups for now by properly ignoring +the non-existing queues, so the indicator bits will match the queue +indexes. + +[1] https://lore.kernel.org/all/cover.1720611677.git.mst@redhat.com/ + +Fixes: a229989d975e ("virtio: don't allocate vqs when names[i] = NULL") +Reported-by: Chandra Merla +Cc: stable@vger.kernel.org +Signed-off-by: David Hildenbrand +Tested-by: Thomas Huth +Reviewed-by: Thomas Huth +Reviewed-by: Cornelia Huck +Acked-by: Michael S. Tsirkin +Acked-by: Christian Borntraeger +Link: https://lore.kernel.org/r/20250402203621.940090-1-david@redhat.com +Signed-off-by: Heiko Carstens +Signed-off-by: David Hildenbrand +Signed-off-by: Greg Kroah-Hartman +--- + drivers/s390/virtio/virtio_ccw.c | 16 ++++++++++++---- + 1 file changed, 12 insertions(+), 4 deletions(-) + +--- a/drivers/s390/virtio/virtio_ccw.c ++++ b/drivers/s390/virtio/virtio_ccw.c +@@ -261,11 +261,17 @@ static struct airq_info *new_airq_info(i + static unsigned long get_airq_indicator(struct virtqueue *vqs[], int nvqs, + u64 *first, void **airq_info) + { +- int i, j; ++ int i, j, queue_idx, highest_queue_idx = -1; + struct airq_info *info; + unsigned long indicator_addr = 0; + unsigned long bit, flags; + ++ /* Array entries without an actual queue pointer must be ignored. */ ++ for (i = 0; i < nvqs; i++) { ++ if (vqs[i]) ++ highest_queue_idx++; ++ } ++ + for (i = 0; i < MAX_AIRQ_AREAS && !indicator_addr; i++) { + mutex_lock(&airq_areas_lock); + if (!airq_areas[i]) +@@ -275,7 +281,7 @@ static unsigned long get_airq_indicator( + if (!info) + return 0; + write_lock_irqsave(&info->lock, flags); +- bit = airq_iv_alloc(info->aiv, nvqs); ++ bit = airq_iv_alloc(info->aiv, highest_queue_idx + 1); + if (bit == -1UL) { + /* Not enough vacancies. */ + write_unlock_irqrestore(&info->lock, flags); +@@ -284,8 +290,10 @@ static unsigned long get_airq_indicator( + *first = bit; + *airq_info = info; + indicator_addr = (unsigned long)info->aiv->vector; +- for (j = 0; j < nvqs; j++) { +- airq_iv_set_ptr(info->aiv, bit + j, ++ for (j = 0, queue_idx = 0; j < nvqs; j++) { ++ if (!vqs[j]) ++ continue; ++ airq_iv_set_ptr(info->aiv, bit + queue_idx++, + (unsigned long)vqs[j]); + } + write_unlock_irqrestore(&info->lock, flags); diff --git a/queue-5.10/series b/queue-5.10/series index d01ff2306b..5e157b9b38 100644 --- a/queue-5.10/series +++ b/queue-5.10/series @@ -280,3 +280,4 @@ x86-bugs-don-t-fill-rsb-on-vmexit-with-eibrs-retpoli.patch ext4-make-block-validity-check-resistent-to-sb-bh-co.patch scsi-pm80xx-set-phy_attached-to-zero-when-device-is-.patch md-raid1-add-check-for-missing-source-disk-in-proces.patch +s390-virtio_ccw-don-t-allocate-assign-airqs-for-non-existing-queues.patch