[Xen-devel] [PATCH 0/8] xen: don't let keyhandlers block indefinitely on locks

From: Juergen Gross <jgross@suse.com>
To: xen-devel@lists.xenproject.org
Cc: "Juergen Gross" <jgross@suse.com>,
	"Kevin Tian" <kevin.tian@intel.com>,
	"Stefano Stabellini" <sstabellini@kernel.org>,
	"Julien Grall" <julien@xen.org>,
	"Jun Nakajima" <jun.nakajima@intel.com>, "Wei Liu" <wl@xen.org>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	"George Dunlap" <George.Dunlap@eu.citrix.com>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Ian Jackson" <ian.jackson@eu.citrix.com>,
	"Dario Faggioli" <dfaggioli@suse.com>,
	"Ross Lagerwall" <ross.lagerwall@citrix.com>,
	"Meng Xu" <mengxu@cis.upenn.edu>,
	"Jan Beulich" <jbeulich@suse.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: [Xen-devel] [PATCH 0/8] xen: don't let keyhandlers block indefinitely on locks
Date: Thu, 13 Feb 2020 13:54:41 +0100	[thread overview]
Message-ID: <20200213125449.14226-1-jgross@suse.com> (raw)

Keyhandlers dumping hypervisor information to the console often need
to take locks while accessing data. In order to not block in case of
system inconsistencies it is convenient to use trylock variants when
obtaining the locks. On the other hand a busy system might easily
encounter held locks, so this patch series is adding special trylock
variants with a timeout used by keyhandlers.

Only the keyhandlers dumping out data are modified to use those new
lock variants. There might be still some potentially blocking locks
involved (e.g. the console lock for printing), but most critical
cases should be handled by this series.

The timeout per lock is 1 millisecond as default, the value can be
changed by boot and runtime parameter setting.

Patch 1: cleanup (can go in independently of all other patches)
Patch 2: fix in keyhandlers where domlist_read_lock was not taken when
         using for_each_domain() (can go in independently)
Patch 3: cleanup of lock handling in scheduling code (prerequisite
         patch for patch 5)
Patch 4: main infrastructure for trylocks with timeout plus adaption
         of keyhandlers directly in keyhandler.c
Patches 5-8: adaptions of other keyhandlers (split roughly by path)

Juergen Gross (8):
  xen: make rangeset_printk() static
  xen: add using domlist_read_lock in keyhandlers
  xen/sched: don't use irqsave locks in dumping functions
  xen: add locks with timeouts for keyhandlers
  xen/sched: use keyhandler locks when dumping data to console
  xen/common: use keyhandler locks when dumping data to console
  xen/drivers: use keyhandler locks when dumping data to console
  xen/x86: use keyhandler locks when dumping data to console

 docs/misc/xen-command-line.pandoc        |  9 ++++++
 xen/arch/x86/domain.c                    |  9 ++++--
 xen/arch/x86/io_apic.c                   | 53 ++++++++++++++++++++++++--------
 xen/arch/x86/irq.c                       |  5 ++-
 xen/arch/x86/mm/p2m-ept.c                |  4 +++
 xen/arch/x86/msi.c                       |  4 ++-
 xen/arch/x86/numa.c                      | 16 ++++++----
 xen/arch/x86/time.c                      |  5 +++
 xen/common/event_channel.c               |  3 +-
 xen/common/grant_table.c                 | 39 +++++++++++++++++++++--
 xen/common/keyhandler.c                  | 29 ++++++++++++++++-
 xen/common/livepatch.c                   | 11 ++-----
 xen/common/rangeset.c                    | 10 +++---
 xen/common/sched/core.c                  |  7 +++++
 xen/common/sched/cpupool.c               |  4 ++-
 xen/common/sched/credit.c                | 31 ++++++++++++-------
 xen/common/sched/credit2.c               | 20 +++++++-----
 xen/common/sched/null.c                  | 50 +++++++++++++++++-------------
 xen/common/sched/private.h               |  1 +
 xen/common/sched/rt.c                    | 13 ++++----
 xen/common/spinlock.c                    | 18 +++++++++--
 xen/common/timer.c                       | 15 +++++----
 xen/drivers/passthrough/amd/iommu_intr.c | 14 ++++++---
 xen/drivers/passthrough/iommu.c          |  5 +++
 xen/drivers/passthrough/pci.c            | 14 +++++++--
 xen/drivers/vpci/msi.c                   |  5 ++-
 xen/include/xen/keyhandler.h             | 26 ++++++++++++++++
 xen/include/xen/rangeset.h               |  2 --
 xen/include/xen/rwlock.h                 | 37 ++++++++++++++++++++++
 29 files changed, 352 insertions(+), 107 deletions(-)

-- 
2.16.4

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