linux-toradex.git/drivers/xen/manage.c, branch v4.9.121

xen: don't print error message in case of missing Xenstore entry

2017-11-08T09:08:37+00:00

[ Upstream commit 4e93b6481c87ea5afde944a32b4908357ec58992 ]

When registering for the Xenstore watch of the node control/sysrq the
handler will be called at once. Don't issue an error message if the
Xenstore node isn't there, as it will be created only when an event
is being triggered.

Signed-off-by: Juergen Gross 
Reviewed-by: Boris Ostrovsky 
Signed-off-by: Juergen Gross 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

xen/manage: correct return value check on xenbus_scanf()

2017-11-08T09:08:35+00:00

[ Upstream commit 4fed1b125eb6252bde478665fc05d4819f774fa8 ]

A negative return value indicates an error; in fact the function at
present won't ever return zero.

Signed-off-by: Jan Beulich 
Reviewed-by: Juergen Gross 
Signed-off-by: Boris Ostrovsky 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

xenbus: advertise control feature flags

2016-10-24T14:48:40+00:00

The Xen docs specify several flags which a guest can set to advertise
which values of the xenstore control/shutdown key it will recognize.
This patch adds code to write all the relevant feature-flag keys.

Based-on-patch-by: Paul Durrant 
Signed-off-by: Juergen Gross 
Reviewed-by: David Vrabel 
Reviewed-by: Paul Durrant 
Signed-off-by: David Vrabel

xen: Use correctly the Xen memory terminologies

2015-09-08T17:03:49+00:00

Based on include/xen/mm.h [1], Linux is mistakenly using MFN when GFN
is meant, I suspect this is because the first support for Xen was for
PV. This resulted in some misimplementation of helpers on ARM and
confused developers about the expected behavior.

For instance, with pfn_to_mfn, we expect to get an MFN based on the name.
Although, if we look at the implementation on x86, it's returning a GFN.

For clarity and avoid new confusion, replace any reference to mfn with
gfn in any helpers used by PV drivers. The x86 code will still keep some
reference of pfn_to_mfn which may be used by all kind of guests
No changes as been made in the hypercall field, even
though they may be invalid, in order to keep the same as the defintion
in xen repo.

Note that page_to_mfn has been renamed to xen_page_to_gfn to avoid a
name to close to the KVM function gfn_to_page.

Take also the opportunity to simplify simple construction such
as pfn_to_mfn(page_to_pfn(page)) into xen_page_to_gfn. More complex clean up
will come in follow-up patches.

[1] http://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=e758ed14f390342513405dd766e874934573e6cb

Signed-off-by: Julien Grall 
Reviewed-by: Stefano Stabellini 
Acked-by: Dmitry Torokhov 
Acked-by: Wei Liu 
Signed-off-by: David Vrabel

xen: Include xen/page.h rather than asm/xen/page.h

2015-06-17T15:14:18+00:00

Using xen/page.h will be necessary later for using common xen page
helpers.

As xen/page.h already include asm/xen/page.h, always use the later.

Signed-off-by: Julien Grall 
Reviewed-by: David Vrabel 
Cc: Stefano Stabellini 
Cc: Ian Campbell 
Cc: Wei Liu 
Cc: Konrad Rzeszutek Wilk 
Cc: Boris Ostrovsky 
Cc: netdev@vger.kernel.org
Signed-off-by: David Vrabel

xen: Suspend ticks on all CPUs during suspend

2015-04-29T16:10:05+00:00

Commit 77e32c89a711 ("clockevents: Manage device's state separately for
the core") decouples clockevent device's modes from states. With this
change when a Xen guest tries to resume, it won't be calling its
set_mode op which needs to be done on each VCPU in order to make the
hypervisor aware that we are in oneshot mode.

This happens because clockevents_tick_resume() (which is an intermediate
step of resuming ticks on a processor) doesn't call clockevents_set_state()
anymore and because during suspend clockevent devices on all VCPUs (except
for the one doing the suspend) are left in ONESHOT state. As result, during
resume the clockevents state machine will assume that device is already
where it should be and doesn't need to be updated.

To avoid this problem we should suspend ticks on all VCPUs during
suspend.

Signed-off-by: Boris Ostrovsky 
Signed-off-by: David Vrabel

xen/manage: Fix USB interaction issues when resuming

2015-02-06T15:49:09+00:00

Commit 61a734d305e1 ("xen/manage: Always freeze/thaw processes when
suspend/resuming") ensured that userspace processes were always frozen
before suspending to reduce interaction issues when resuming devices.
However, freeze_processes() does not freeze kernel threads.  Freeze
kernel threads as well to prevent deadlocks with the khubd thread when
resuming devices.

This is what native suspend and resume does.

Example deadlock:
[ 7279.648010]  [] ? xen_poll_irq_timeout+0x3e/0x50
[ 7279.648010]  [] xen_poll_irq+0x10/0x20
[ 7279.648010]  [] xen_lock_spinning+0xb3/0x120
[ 7279.648010]  [] __raw_callee_save_xen_lock_spinning+0x11/0x20
[ 7279.648010]  [] ? usb_control_msg+0xe6/0x120
[ 7279.648010]  [] ? _raw_spin_lock_irq+0x50/0x60
[ 7279.648010]  [] wait_for_completion+0xac/0x160
[ 7279.648010]  [] ? try_to_wake_up+0x2c0/0x2c0
[ 7279.648010]  [] dpm_wait+0x32/0x40
[ 7279.648010]  [] device_resume+0x90/0x210
[ 7279.648010]  [] dpm_resume+0x121/0x250
[ 7279.648010]  [] ? xenbus_dev_request_and_reply+0xc0/0xc0
[ 7279.648010]  [] dpm_resume_end+0x15/0x30
[ 7279.648010]  [] do_suspend+0x10a/0x200
[ 7279.648010]  [] ? xen_pre_suspend+0x20/0x20
[ 7279.648010]  [] shutdown_handler+0x120/0x150
[ 7279.648010]  [] xenwatch_thread+0x9f/0x160
[ 7279.648010]  [] ? finish_wait+0x80/0x80
[ 7279.648010]  [] kthread+0xc9/0xe0
[ 7279.648010]  [] ? flush_kthread_worker+0x80/0x80
[ 7279.648010]  [] ret_from_fork+0x7c/0xb0
[ 7279.648010]  [] ? flush_kthread_worker+0x80/0x80

[ 7441.216287] INFO: task khubd:89 blocked for more than 120 seconds.
[ 7441.219457]       Tainted: G            X 3.13.11-ckt12.kz #1
[ 7441.222176] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 7441.225827] khubd           D ffff88003f433440     0    89      2 0x00000000
[ 7441.229258]  ffff88003ceb9b98 0000000000000046 ffff88003ce83000 0000000000013440
[ 7441.232959]  ffff88003ceb9fd8 0000000000013440 ffff88003cd13000 ffff88003ce83000
[ 7441.236658]  0000000000000286 ffff88003d3e0000 ffff88003ceb9bd0 00000001001aa01e
[ 7441.240415] Call Trace:
[ 7441.241614]  [] schedule+0x29/0x70
[ 7441.243930]  [] schedule_timeout+0x166/0x2c0
[ 7441.246681]  [] ? call_timer_fn+0x110/0x110
[ 7441.249339]  [] schedule_timeout_uninterruptible+0x1e/0x20
[ 7441.252644]  [] msleep+0x20/0x30
[ 7441.254812]  [] hub_port_reset+0xf0/0x580
[ 7441.257400]  [] hub_port_init+0x75/0xb40
[ 7441.259981]  [] ? update_autosuspend+0x39/0x60
[ 7441.262817]  [] ? pm_runtime_set_autosuspend_delay+0x50/0xa0
[ 7441.266212]  [] hub_thread+0x71a/0x1750
[ 7441.268728]  [] ? finish_wait+0x80/0x80
[ 7441.271272]  [] ? usb_port_resume+0x670/0x670
[ 7441.274067]  [] kthread+0xc9/0xe0
[ 7441.276305]  [] ? flush_kthread_worker+0x80/0x80
[ 7441.279131]  [] ret_from_fork+0x7c/0xb0
[ 7441.281659]  [] ? flush_kthread_worker+0x80/0x80

Signed-off-by: Ross Lagerwall 
Cc: stable@vger.kernel.org
Signed-off-by: David Vrabel

xen/manage: Always freeze/thaw processes when suspend/resuming

2014-09-02T14:36:59+00:00

Always freeze processes when suspending and thaw processes when resuming
to prevent a race noticeable with HVM guests.

This prevents a deadlock where the khubd kthread (which is designed to
be freezable) acquires a usb device lock and then tries to allocate
memory which requires the disk which hasn't been resumed yet.
Meanwhile, the xenwatch thread deadlocks waiting for the usb device
lock.

Freezing processes fixes this because the khubd thread is only thawed
after the xenwatch thread finishes resuming all the devices.

Signed-off-by: Ross Lagerwall 
Signed-off-by: David Vrabel 
Cc: stable@vger.kernel.org

xen/manage: fix potential deadlock when resuming the console

2014-07-03T10:02:28+00:00

Calling xen_console_resume() in xen_suspend() causes a warning because
it locks irq_mapping_update_lock (a mutex) and this may sleep.  If a
userspace process is using the evtchn device then this mutex may be
locked at the point of the stop_machine() call and
xen_console_resume() would then deadlock.

Resuming the console after stop_machine() returns avoids this
deadlock.

Signed-off-by: David Vrabel 
Reviewed-by: Boris Ostrovsky 
Cc:

xen: refactor suspend pre/post hooks

2014-05-12T16:19:56+00:00

New architectures currently have to provide implementations of 5 different
functions: xen_arch_pre_suspend(), xen_arch_post_suspend(),
xen_arch_hvm_post_suspend(), xen_mm_pin_all(), and xen_mm_unpin_all().

Refactor the suspend code to only require xen_arch_pre_suspend() and
xen_arch_post_suspend().

Signed-off-by: David Vrabel 
Reviewed-by: Boris Ostrovsky