linux-stable.git/drivers/xen, branch v5.4.151

xen/balloon: fix balloon kthread freezing

2021-09-30T08:09:26+00:00

commit 96f5bd03e1be606987644b71899ea56a8d05f825 upstream.

Commit 8480ed9c2bbd56 ("xen/balloon: use a kernel thread instead a
workqueue") switched the Xen balloon driver to use a kernel thread.
Unfortunately the patch omitted to call try_to_freeze() or to use
wait_event_freezable_timeout(), causing a system suspend to fail.

Fixes: 8480ed9c2bbd56 ("xen/balloon: use a kernel thread instead a workqueue")
Signed-off-by: Juergen Gross 
Reviewed-by: Boris Ostrovsky 
Link: https://lore.kernel.org/r/20210920100345.21939-1-jgross@suse.com
Signed-off-by: Juergen Gross 
Signed-off-by: Greg Kroah-Hartman

xen/balloon: use a kernel thread instead a workqueue

2021-09-30T08:09:25+00:00

[ Upstream commit 8480ed9c2bbd56fc86524998e5f2e3e22f5038f6 ]

Today the Xen ballooning is done via delayed work in a workqueue. This
might result in workqueue hangups being reported in case of large
amounts of memory are being ballooned in one go (here 16GB):

BUG: workqueue lockup - pool cpus=6 node=0 flags=0x0 nice=0 stuck for 64s!
Showing busy workqueues and worker pools:
workqueue events: flags=0x0
  pwq 12: cpus=6 node=0 flags=0x0 nice=0 active=2/256 refcnt=3
    in-flight: 229:balloon_process
    pending: cache_reap
workqueue events_freezable_power_: flags=0x84
  pwq 12: cpus=6 node=0 flags=0x0 nice=0 active=1/256 refcnt=2
    pending: disk_events_workfn
workqueue mm_percpu_wq: flags=0x8
  pwq 12: cpus=6 node=0 flags=0x0 nice=0 active=1/256 refcnt=2
    pending: vmstat_update
pool 12: cpus=6 node=0 flags=0x0 nice=0 hung=64s workers=3 idle: 2222 43

This can easily be avoided by using a dedicated kernel thread for doing
the ballooning work.

Reported-by: Jan Beulich 
Signed-off-by: Juergen Gross 
Reviewed-by: Boris Ostrovsky 
Link: https://lore.kernel.org/r/20210827123206.15429-1-jgross@suse.com
Signed-off-by: Juergen Gross 
Signed-off-by: Sasha Levin

xen/events: Fix race in set_evtchn_to_irq

2021-08-18T06:57:01+00:00

[ Upstream commit 88ca2521bd5b4e8b83743c01a2d4cb09325b51e9 ]

There is a TOCTOU issue in set_evtchn_to_irq. Rows in the evtchn_to_irq
mapping are lazily allocated in this function. The check whether the row
is already present and the row initialization is not synchronized. Two
threads can at the same time allocate a new row for evtchn_to_irq and
add the irq mapping to the their newly allocated row. One thread will
overwrite what the other has set for evtchn_to_irq[row] and therefore
the irq mapping is lost. This will trigger a BUG_ON later in
bind_evtchn_to_cpu:

  INFO: pci 0000:1a:15.4: [1d0f:8061] type 00 class 0x010802
  INFO: nvme 0000:1a:12.1: enabling device (0000 -> 0002)
  INFO: nvme nvme77: 1/0/0 default/read/poll queues
  CRIT: kernel BUG at drivers/xen/events/events_base.c:427!
  WARN: invalid opcode: 0000 [#1] SMP NOPTI
  WARN: Workqueue: nvme-reset-wq nvme_reset_work [nvme]
  WARN: RIP: e030:bind_evtchn_to_cpu+0xc2/0xd0
  WARN: Call Trace:
  WARN:  set_affinity_irq+0x121/0x150
  WARN:  irq_do_set_affinity+0x37/0xe0
  WARN:  irq_setup_affinity+0xf6/0x170
  WARN:  irq_startup+0x64/0xe0
  WARN:  __setup_irq+0x69e/0x740
  WARN:  ? request_threaded_irq+0xad/0x160
  WARN:  request_threaded_irq+0xf5/0x160
  WARN:  ? nvme_timeout+0x2f0/0x2f0 [nvme]
  WARN:  pci_request_irq+0xa9/0xf0
  WARN:  ? pci_alloc_irq_vectors_affinity+0xbb/0x130
  WARN:  queue_request_irq+0x4c/0x70 [nvme]
  WARN:  nvme_reset_work+0x82d/0x1550 [nvme]
  WARN:  ? check_preempt_wakeup+0x14f/0x230
  WARN:  ? check_preempt_curr+0x29/0x80
  WARN:  ? nvme_irq_check+0x30/0x30 [nvme]
  WARN:  process_one_work+0x18e/0x3c0
  WARN:  worker_thread+0x30/0x3a0
  WARN:  ? process_one_work+0x3c0/0x3c0
  WARN:  kthread+0x113/0x130
  WARN:  ? kthread_park+0x90/0x90
  WARN:  ret_from_fork+0x3a/0x50

This patch sets evtchn_to_irq rows via a cmpxchg operation so that they
will be set only once. The row is now cleared before writing it to
evtchn_to_irq in order to not create a race once the row is visible for
other threads.

While at it, do not require the page to be zeroed, because it will be
overwritten with -1's in clear_evtchn_to_irq_row anyway.

Signed-off-by: Maximilian Heyne 
Fixes: d0b075ffeede ("xen/events: Refactor evtchn_to_irq array to be dynamically allocated")
Link: https://lore.kernel.org/r/20210812130930.127134-1-mheyne@amazon.de
Reviewed-by: Boris Ostrovsky 
Signed-off-by: Boris Ostrovsky 
Signed-off-by: Sasha Levin

xen/events: reset active flag for lateeoi events later

2021-07-11T10:52:08+00:00

commit 3de218ff39b9e3f0d453fe3154f12a174de44b25 upstream.

In order to avoid a race condition for user events when changing
cpu affinity reset the active flag only when EOI-ing the event.

This is working fine as all user events are lateeoi events. Note that
lateeoi_ack_mask_dynirq() is not modified as there is no explicit call
to xen_irq_lateeoi() expected later.

Cc: stable@vger.kernel.org
Reported-by: Julien Grall 
Fixes: b6622798bc50b62 ("xen/events: avoid handling the same event on two cpus at the same time")
Tested-by: Julien Grall 
Signed-off-by: Juergen Gross 
Reviewed-by: Boris Ostrovsky 
Link: https://lore.kernel.org/r/20210623130913.9405-1-jgross@suse.com
Signed-off-by: Juergen Gross 
Signed-off-by: Greg Kroah-Hartman

xen-pciback: redo VF placement in the virtual topology

2021-06-10T11:37:16+00:00

The commit referenced below was incomplete: It merely affected what
would get written to the vdev- xenstore node. The guest would still
find the function at the original function number as long as
__xen_pcibk_get_pci_dev() wouldn't be in sync. The same goes for AER wrt
__xen_pcibk_get_pcifront_dev().

Undo overriding the function to zero and instead make sure that VFs at
function zero remain alone in their slot. This has the added benefit of
improving overall capacity, considering that there's only a total of 32
slots available right now (PCI segment and bus can both only ever be
zero at present).

This is upstream commit 4ba50e7c423c29639878c00573288869aa627068.

Fixes: 8a5248fe10b1 ("xen PV passthru: assign SR-IOV virtual functions to 
separate virtual slots")
Signed-off-by: Jan Beulich 
Reviewed-by: Boris Ostrovsky 
Link: https://lore.kernel.org/r/8def783b-404c-3452-196d-3f3fd4d72c9e@suse.com
Signed-off-by: Juergen Gross 
Signed-off-by: Greg Kroah-Hartman

xen-pciback: reconfigure also from backend watch handler

2021-05-26T10:05:18+00:00

commit c81d3d24602540f65256f98831d0a25599ea6b87 upstream.

When multiple PCI devices get assigned to a guest right at boot, libxl
incrementally populates the backend tree. The writes for the first of
the devices trigger the backend watch. In turn xen_pcibk_setup_backend()
will set the XenBus state to Initialised, at which point no further
reconfigures would happen unless a device got hotplugged. Arrange for
reconfigure to also get triggered from the backend watch handler.

Signed-off-by: Jan Beulich 
Cc: stable@vger.kernel.org
Reviewed-by: Boris Ostrovsky 
Link: https://lore.kernel.org/r/2337cbd6-94b9-4187-9862-c03ea12e0c61@suse.com
Signed-off-by: Juergen Gross 
Signed-off-by: Greg Kroah-Hartman

xen/events: fix setting irq affinity

2021-04-16T09:46:39+00:00

The backport of upstream patch 25da4618af240fbec61 ("xen/events: don't
unmask an event channel when an eoi is pending") introduced a
regression for stable kernels 5.10 and older: setting IRQ affinity for
IRQs related to interdomain events would no longer work, as moving the
IRQ to its new cpu was not included in the irq_ack callback for those
events.

Fix that by adding the needed call.

Note that kernels 5.11 and later don't need the explicit moving of the
IRQ to the target cpu in the irq_ack callback, due to a rework of the
affinity setting in kernel 5.11.

Signed-off-by: Juergen Gross 
Signed-off-by: Greg Kroah-Hartman

xen/evtchn: Change irq_info lock to raw_spinlock_t

2021-04-14T06:24:10+00:00

commit d120198bd5ff1d41808b6914e1eb89aff937415c upstream.

Unmask operation must be called with interrupt disabled,
on preempt_rt spin_lock_irqsave/spin_unlock_irqrestore
don't disable/enable interrupts, so use raw_* implementation
and change lock variable in struct irq_info from spinlock_t
to raw_spinlock_t

Cc: stable@vger.kernel.org
Fixes: 25da4618af24 ("xen/events: don't unmask an event channel when an eoi is pending")
Signed-off-by: Luca Fancellu 
Reviewed-by: Julien Grall 
Reviewed-by: Wei Liu 
Link: https://lore.kernel.org/r/20210406105105.10141-1-luca.fancellu@arm.com
Signed-off-by: Boris Ostrovsky 
Signed-off-by: Greg Kroah-Hartman

xen/events: avoid handling the same event on two cpus at the same time

2021-03-17T16:03:58+00:00

commit b6622798bc50b625a1e62f82c7190df40c1f5b21 upstream.

When changing the cpu affinity of an event it can happen today that
(with some unlucky timing) the same event will be handled on the old
and the new cpu at the same time.

Avoid that by adding an "event active" flag to the per-event data and
call the handler only if this flag isn't set.

Cc: stable@vger.kernel.org
Reported-by: Julien Grall 
Signed-off-by: Juergen Gross 
Reviewed-by: Julien Grall 
Link: https://lore.kernel.org/r/20210306161833.4552-4-jgross@suse.com
Signed-off-by: Boris Ostrovsky 
Signed-off-by: Greg Kroah-Hartman

xen/events: don't unmask an event channel when an eoi is pending

2021-03-17T16:03:58+00:00

commit 25da4618af240fbec6112401498301a6f2bc9702 upstream.

An event channel should be kept masked when an eoi is pending for it.
When being migrated to another cpu it might be unmasked, though.

In order to avoid this keep three different flags for each event channel
to be able to distinguish "normal" masking/unmasking from eoi related
masking/unmasking and temporary masking. The event channel should only
be able to generate an interrupt if all flags are cleared.

Cc: stable@vger.kernel.org
Fixes: 54c9de89895e ("xen/events: add a new "late EOI" evtchn framework")
Reported-by: Julien Grall 
Signed-off-by: Juergen Gross 
Reviewed-by: Julien Grall 
Reviewed-by: Boris Ostrovsky 
Tested-by: Ross Lagerwall 
Link: https://lore.kernel.org/r/20210306161833.4552-3-jgross@suse.com

[boris -- corrected Fixed tag format]

Signed-off-by: Boris Ostrovsky 
Signed-off-by: Greg Kroah-Hartman