I was seeing a very odd crash on 64 bit in bind_evtchn_to_cpu because
cpu_from_irq(irq) was coming out as -1. I found this was coming direct
from the mk_ipi_info call.
It's not clear to me that this isn't a compiler bug (implicit
initialisation to zero of unsigned shorts in a struct not handled
correctly?).
On the other hand is it true that all event channels start of bound to
CPU 0? If not then -1 might be correct and the various other functions
should cope with this.
Signed-off-by: Ian Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Make sure that irq_enter()/irq_exit() wrap the entire event processing
loop, rather than each individual event invokation. This makes sure
that softirq processing is deferred until the end of event processing,
rather than in the middle with interrupts disabled.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
There should be no need for us to maintain our own bind count for
irqs, since the surrounding irq system should keep track of shared
irqs for us.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Put all irq info into one struct. Also, use a union to keep
event channel type-specific information, rather than overloading the
index field.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Rather than overloading vectors for event channels, take full
responsibility for mapping an event channel to irq directly. With
this patch Xen has its own irq allocator.
When the kernel gets an event channel upcall, it maps the event
channel number to an irq and injects it into the normal interrupt
path.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
By default, the irq_chip.disable operation is a no-op. Explicitly set
it to disable the Xen event channel.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix bootup crash on xen guests
SLAB is not yet up, with earlyprintk it is giving me an Oops in __kmalloc.
Replace call to kmalloc() with alloc_bootmem().
Reported-by: Christophe Saout <christophe@saout.de>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: reduce memory usage.
Reduce this significant gain in the amount of memory used
when NR_CPUS bumped from 128 to 4096 by allocating the
array based on nr_cpu_ids:
65536 +2031616 2097152 +3100% cpu_evtchn_mask(.bss)
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: virtualization@lists.osdl.org
Cc: xen-devel@lists.xensource.com
Impact: reduce memory usage, use new cpumask API.
Replace the affinity and pending_masks with cpumask_var_t's. This adds
to the significant size reduction done with the SPARSE_IRQS changes.
The added functions (init_alloc_desc_masks & init_copy_desc_masks) are
in the include file so they can be inlined (and optimized out for the
!CONFIG_CPUMASKS_OFFSTACK case.) [Naming chosen to be consistent with
the other init*irq functions, as well as the backwards arg declaration
of "from, to" instead of the more common "to, from" standard.]
Includes a slight change to the declaration of struct irq_desc to embed
the pending_mask within ifdef(CONFIG_SMP) to be consistent with other
references, and some small changes to Xen.
Tested: sparse/non-sparse/cpumask_offstack/non-cpumask_offstack/nonuma/nosmp on x86_64
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: virtualization@lists.osdl.org
Cc: xen-devel@lists.xensource.com
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
* 'cpus4096-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (66 commits)
x86: export vector_used_by_percpu_irq
x86: use logical apicid in x2apic_cluster's x2apic_cpu_mask_to_apicid_and()
sched: nominate preferred wakeup cpu, fix
x86: fix lguest used_vectors breakage, -v2
x86: fix warning in arch/x86/kernel/io_apic.c
sched: fix warning in kernel/sched.c
sched: move test_sd_parent() to an SMP section of sched.h
sched: add SD_BALANCE_NEWIDLE at MC and CPU level for sched_mc>0
sched: activate active load balancing in new idle cpus
sched: bias task wakeups to preferred semi-idle packages
sched: nominate preferred wakeup cpu
sched: favour lower logical cpu number for sched_mc balance
sched: framework for sched_mc/smt_power_savings=N
sched: convert BALANCE_FOR_xx_POWER to inline functions
x86: use possible_cpus=NUM to extend the possible cpus allowed
x86: fix cpu_mask_to_apicid_and to include cpu_online_mask
x86: update io_apic.c to the new cpumask code
x86: Introduce topology_core_cpumask()/topology_thread_cpumask()
x86: xen: use smp_call_function_many()
x86: use work_on_cpu in x86/kernel/cpu/mcheck/mce_amd_64.c
...
Fixed up trivial conflict in kernel/time/tick-sched.c manually
Impact: cleanup
all for_each_irq_desc() usage point have !desc check.
then its check can move into for_each_irq_desc() macro.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix crash
Make sure all Xen irqs have an irq_desc.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: change existing irq_chip API
Not much point with gentle transition here: the struct irq_chip's
setaffinity method signature needs to change.
Fortunately, not widely used code, but hits a few architectures.
Note: In irq_select_affinity() I save a temporary in by mangling
irq_desc[irq].affinity directly. Ingo, does this break anything?
(Folded in fix from KOSAKI Motohiro)
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Grant Grundler <grundler@parisc-linux.org>
Acked-by: Ingo Molnar <mingo@redhat.com>
Cc: ralf@linux-mips.org
Cc: grundler@parisc-linux.org
Cc: jeremy@xensource.com
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Impact: new feature
Problem on distro kernels: irq_desc[NR_IRQS] takes megabytes of RAM with
NR_CPUS set to large values. The goal is to be able to scale up to much
larger NR_IRQS value without impacting the (important) common case.
To solve this, we generalize irq_desc[NR_IRQS] to an (optional) array of
irq_desc pointers.
When CONFIG_SPARSE_IRQ=y is used, we use kzalloc_node to get irq_desc,
this also makes the IRQ descriptors NUMA-local (to the site that calls
request_irq()).
This gets rid of the irq_cfg[] static array on x86 as well: irq_cfg now
uses desc->chip_data for x86 to store irq_cfg.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When sparse IRQs are enabled, it is not safe to assume an IRQ descriptor
exists for every possible IRQ. This patch causes init_evtchn_cpu_bindings
to skip initialisation of IRQ descriptors which don't exist.
Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
add CONFIG_HAVE_SPARSE_IRQ to for use condensed array.
Get rid of irq_desc[] array assumptions.
Preallocate 32 irq_desc, and irq_desc() will try to get more.
( No change in functionality is expected anywhere, except the odd build
failure where we missed a code site or where a crossing commit itroduces
new irq_desc[] usage. )
v2: according to Eric, change get_irq_desc() to irq_desc()
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Note the changes from 2.6.18-xen CPU hotplugging:
A vcpu_down request from the remote admin via Xenbus both hotunplugs the
CPU, and disables it by removing it from the cpu_present map, and removing
its entry in /sys.
A vcpu_up request from the remote admin only re-enables the CPU, and does
not immediately bring the CPU up. A udev event is emitted, which can be
caught by the user if he wishes to automatically re-up CPUs when available,
or implement a more complex policy.
Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
A spinlock can be interrupted while spinning, so make sure we preserve
the previous lock of interest if we're taking a lock from within an
interrupt handler.
We also need to deal with the case where the blocking path gets
interrupted between testing to see if the lock is free and actually
blocking. If we get interrupted there and end up in the state where
the lock is free but the irq isn't pending, then we'll block
indefinitely in the hypervisor. This fix is to make sure that any
nested lock-takers will always leave the irq pending if there's any
chance the outer lock became free.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
For some reason I managed to miss a bunch of irq-related functions
which also need to be compiled without -pg when using ftrace. This
patch moves them into their own file, and starts a cleanup process
I've been meaning to do anyway.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: "Alex Nixon (Intern)" <Alex.Nixon@eu.citrix.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The standard ticket spinlocks are very expensive in a virtual
environment, because their performance depends on Xen's scheduler
giving vcpus time in the order that they're supposed to take the
spinlock.
This implements a Xen-specific spinlock, which should be much more
efficient.
The fast-path is essentially the old Linux-x86 locks, using a single
lock byte. The locker decrements the byte; if the result is 0, then
they have the lock. If the lock is negative, then locker must spin
until the lock is positive again.
When there's contention, the locker spin for 2^16[*] iterations waiting
to get the lock. If it fails to get the lock in that time, it adds
itself to the contention count in the lock and blocks on a per-cpu
event channel.
When unlocking the spinlock, the locker looks to see if there's anyone
blocked waiting for the lock by checking for a non-zero waiter count.
If there's a waiter, it traverses the per-cpu "lock_spinners"
variable, which contains which lock each CPU is waiting on. It picks
one CPU waiting on the lock and sends it an event to wake it up.
This allows efficient fast-path spinlock operation, while allowing
spinning vcpus to give up their processor time while waiting for a
contended lock.
[*] 2^16 iterations is threshold at which 98% locks have been taken
according to Thomas Friebel's Xen Summit talk "Preventing Guests from
Spinning Around". Therefore, we'd expect the lock and unlock slow
paths will only be entered 2% of the time.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <clameter@linux-foundation.org>
Cc: Petr Tesarik <ptesarik@suse.cz>
Cc: Virtualization <virtualization@lists.linux-foundation.org>
Cc: Xen devel <xen-devel@lists.xensource.com>
Cc: Thomas Friebel <thomas.friebel@amd.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch is ported one from 534:77db69c38249 of linux-2.6.18-xen.hg.
Use wmb instead of rmb to enforce ordering between
evtchn_upcall_pending and evtchn_pending_sel stores
in xen_evtchn_do_upcall().
Cc: Samuel Thibault <samuel.thibault@eu.citrix.com>
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: the arch/x86 maintainers <x86@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch implements Xen save/restore and migration.
Saving is triggered via xenbus, which is polled in
drivers/xen/manage.c. When a suspend request comes in, the kernel
prepares itself for saving by:
1 - Freeze all processes. This is primarily to prevent any
partially-completed pagetable updates from confusing the suspend
process. If CONFIG_PREEMPT isn't defined, then this isn't necessary.
2 - Suspend xenbus and other devices
3 - Stop_machine, to make sure all the other vcpus are quiescent. The
Xen tools require the domain to run its save off vcpu0.
4 - Within the stop_machine state, it pins any unpinned pgds (under
construction or destruction), performs canonicalizes various other
pieces of state (mostly converting mfns to pfns), and finally
5 - Suspend the domain
Restore reverses the steps used to save the domain, ending when all
the frozen processes are thawed.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Rearrange the tests in unbind_from_irq() so that we can still unbind
an irq even if the underlying event channel is bad. This allows a
device driver to shuffle its irqs on save/restore before the
underlying event channels have been fixed up.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add rebind_evtchn_irq(), which will rebind an device driver's existing
irq to a new event channel on restore. Since the new event channel
will be masked and bound to vcpu0, we update the state accordingly and
unmask the irq once everything is set up.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Define resend_irq_on_evtchn() which ia64/xen uses.
Although it isn't used by current x86/xen code, it's arch generic
so that put it into common code.
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Remove x86 dependency in drivers/xen/events.c for ia64/xen support
introducing include/asm/xen/events.h.
Introduce xen_irqs_disabled() to hide regs->flags
Introduce xen_do_IRQ() to hide regs->orig_ax.
make enum ipi_vector definition arch specific. ia64/xen needs four vectors.
Add one rmb() because on ia64 xchg() isn't barrier.
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
move arch/x86/xen/events.c undedr drivers/xen to share codes
with x86 and ia64. And minor adjustment to compile.
ia64/xen also uses events.c
Signed-off-by: Yaozu (Eddie) Dong <eddie.dong@intel.com>
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Ian Campbell