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These handlers are all referenced from assembler stubs, so need
to be visible.
The handlers without arguments become asmlinkage, the others __visible
to not force regparms(0) on x86-32.
I put it all into a single patch, please let me know if you want
it it split up.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1375740170-7446-4-git-send-email-andi@firstfloor.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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Reschedule vector tracepoints may be called in cpu idle state.
This causes lockdep check warning below.
The tracepoint requires rcu but for accuracy it also
requires irq_enter() (tracepoints record the irq context), thus,
the tracepoint interrupt handler should be calling irq_enter()
and not rcu_irq_enter() (irq_enter() calls rcu_irq_enter()).
So, add irq_enter/exit() to smp_trace_reschedule_interrupt()
with common pre/post processing functions, smp_entering_irq()
and exiting_irq() (exiting_irq() calls just irq_exit()
in arch/x86/include/asm/apic.h),
because these can be shared among reschedule, call_function,
and call_function_single vectors.
[ 50.720557] Testing event reschedule_exit:
[ 50.721349]
[ 50.721502] ===============================
[ 50.721835] [ INFO: suspicious RCU usage. ]
[ 50.722169] 3.10.0-rc6-00004-gcf910e8 #190 Not tainted
[ 50.722582] -------------------------------
[ 50.722915] /c/kernel-tests/src/linux/arch/x86/include/asm/trace/irq_vectors.h:50 suspicious rcu_dereference_check() usage!
[ 50.723770]
[ 50.723770] other info that might help us debug this:
[ 50.723770]
[ 50.724385]
[ 50.724385] RCU used illegally from idle CPU!
[ 50.724385] rcu_scheduler_active = 1, debug_locks = 0
[ 50.725232] RCU used illegally from extended quiescent state!
[ 50.725690] no locks held by swapper/0/0.
[ 50.726010]
[ 50.726010] stack backtrace:
[...]
Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/51CDCFA3.9080101@hds.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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[Purpose of this patch]
As Vaibhav explained in the thread below, tracepoints for irq vectors
are useful.
http://www.spinics.net/lists/mm-commits/msg85707.html
<snip>
The current interrupt traces from irq_handler_entry and irq_handler_exit
provide when an interrupt is handled. They provide good data about when
the system has switched to kernel space and how it affects the currently
running processes.
There are some IRQ vectors which trigger the system into kernel space,
which are not handled in generic IRQ handlers. Tracing such events gives
us the information about IRQ interaction with other system events.
The trace also tells where the system is spending its time. We want to
know which cores are handling interrupts and how they are affecting other
processes in the system. Also, the trace provides information about when
the cores are idle and which interrupts are changing that state.
<snip>
On the other hand, my usecase is tracing just local timer event and
getting a value of instruction pointer.
I suggested to add an argument local timer event to get instruction pointer before.
But there is another way to get it with external module like systemtap.
So, I don't need to add any argument to irq vector tracepoints now.
[Patch Description]
Vaibhav's patch shared a trace point ,irq_vector_entry/irq_vector_exit, in all events.
But there is an above use case to trace specific irq_vector rather than tracing all events.
In this case, we are concerned about overhead due to unwanted events.
So, add following tracepoints instead of introducing irq_vector_entry/exit.
so that we can enable them independently.
- local_timer_vector
- reschedule_vector
- call_function_vector
- call_function_single_vector
- irq_work_entry_vector
- error_apic_vector
- thermal_apic_vector
- threshold_apic_vector
- spurious_apic_vector
- x86_platform_ipi_vector
Also, introduce a logic switching IDT at enabling/disabling time so that a time penalty
makes a zero when tracepoints are disabled. Detailed explanations are as follows.
- Create trace irq handlers with entering_irq()/exiting_irq().
- Create a new IDT, trace_idt_table, at boot time by adding a logic to
_set_gate(). It is just a copy of original idt table.
- Register the new handlers for tracpoints to the new IDT by introducing
macros to alloc_intr_gate() called at registering time of irq_vector handlers.
- Add checking, whether irq vector tracing is on/off, into load_current_idt().
This has to be done below debug checking for these reasons.
- Switching to debug IDT may be kicked while tracing is enabled.
- On the other hands, switching to trace IDT is kicked only when debugging
is disabled.
In addition, the new IDT is created only when CONFIG_TRACING is enabled to avoid being
used for other purposes.
Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/51C323ED.5050708@hds.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
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When implementing tracepoints in interrupt handers, if the tracepoints are
simply added in the performance sensitive path of interrupt handers,
it may cause potential performance problem due to the time penalty.
To solve the problem, an idea is to prepare non-trace/trace irq handers and
switch their IDTs at the enabling/disabling time.
So, let's introduce entering_irq()/exiting_irq() for pre/post-
processing of each irq handler.
A way to use them is as follows.
Non-trace irq handler:
smp_irq_handler()
{
entering_irq(); /* pre-processing of this handler */
__smp_irq_handler(); /*
* common logic between non-trace and trace handlers
* in a vector.
*/
exiting_irq(); /* post-processing of this handler */
}
Trace irq_handler:
smp_trace_irq_handler()
{
entering_irq(); /* pre-processing of this handler */
trace_irq_entry(); /* tracepoint for irq entry */
__smp_irq_handler(); /*
* common logic between non-trace and trace handlers
* in a vector.
*/
trace_irq_exit(); /* tracepoint for irq exit */
exiting_irq(); /* post-processing of this handler */
}
If tracepoints can place outside entering_irq()/exiting_irq() as follows,
it looks cleaner.
smp_trace_irq_handler()
{
trace_irq_entry();
smp_irq_handler();
trace_irq_exit();
}
But it doesn't work.
The problem is with irq_enter/exit() being called. They must be called before
trace_irq_enter/exit(), because of the rcu_irq_enter() must be called before
any tracepoints are used, as tracepoints use rcu to synchronize.
As a possible alternative, we may be able to call irq_enter() first as follows
if irq_enter() can nest.
smp_trace_irq_hander()
{
irq_entry();
trace_irq_entry();
smp_irq_handler();
trace_irq_exit();
irq_exit();
}
But it doesn't work, either.
If irq_enter() is nested, it may have a time penalty because it has to check if it
was already called or not. The time penalty is not desired in performance sensitive
paths even if it is tiny.
Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/51C3238D.9040706@hds.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
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Update the nonmi_ipi parameter to reflect the simple change
instead of the previous complicated one. There should be less
of a need to use it but there may still be corner cases on older
hardware that stumble into NMI issues.
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1336761675-24296-4-git-send-email-dzickus@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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For v3.3, I added code to use the NMI to stop other cpus in the
panic case. The idea was to make sure all cpus on the system
were definitely halted to help serialize the panic path to
execute the rest of the code on a single cpu.
The main problem it was trying to solve was how to stop a cpu
that was spinning with its irqs disabled. A IPI irq would be
stuck and couldn't get in there, but an NMI could.
Things were great until we had another conversation about some
pstore changes. Because some of the backend pstore still uses
spinlocks to protect the device access, things could get ugly if
a panic happened and we were stuck spinning on a lock.
Now with the NMI shutting down cpus, we could assume no other
cpus were running and just bust the spin lock and proceed.
The counter argument was, well if you do that the backend could
be in a screwed up state and you might not be able to save
anything as a result. If we could have just given the cpu a
little more time to finish things, we could have grabbed the
spin lock cleanly and everything would have been fine.
Well, how do give a cpu a 'little more time' in the panic case?
For the most part you can't without spinning on the lock and
even in that case, how long do you spin for?
So instead of making it ugly in the pstore code, just mimic the
idea that stop_machine had, which is block on an IRQ IPI until
the remote cpu has re-enabled interrupts and left the critical
region. Which is what happens now using REBOOT_IRQ.
Then leave the NMI case for those cpus that are truly stuck
after a short time. This leaves the current behaviour alone and
just handle a corner case. Most systems should never have to
enter the NMI code and if they do, print out a message in case
the NMI itself causes another issue.
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1336761675-24296-3-git-send-email-dzickus@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This reverts commit 3603a2512f9e69dc87914ba922eb4a0812b21cd6.
Originally I wanted a better hammer to shutdown cpus during
panic. However, this really steps on the toes of various
spinlocks in the panic path. Sometimes it is easier to wait for
the IRQ to become re-enabled to indictate the cpu left the
critical region and then shutdown the cpu.
The next patch moves the NMI addition after the IRQ part. To
make it easier to see the logic of everything, revert this patch
and apply the next simpler patch.
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1336761675-24296-2-git-send-email-dzickus@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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It was brought to my attention that my x86 change to use NMI in
the reboot path broke Intel Nehalem and Westmere boxes when
using kexec.
I realized I had mistyped the if statement in commit
3603a2512f9e69dc87914ba922eb4a0812b21cd6 and stuck the ')' in
the wrong spot. Putting it in the right spot fixes kexec again.
Doh.
Reported-by: Yinghai Lu <yinghai@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Link: http://lkml.kernel.org/r/1325866671-9797-1-git-send-email-dzickus@redhat.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Some machines may exhibit problems using the NMI to stop other
cpus. This knob just allows one to revert back to the original
behaviour to help diagnose the problem.
V2:
make function static
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <robert.richter@amd.com>
Cc: seiji.aguchi@hds.com
Cc: vgoyal@redhat.com
Cc: mjg@redhat.com
Cc: tony.luck@intel.com
Cc: gong.chen@intel.com
Cc: satoru.moriya@hds.com
Cc: avi@redhat.com
Cc: Andi Kleen <andi@firstfloor.org>
Link: http://lkml.kernel.org/r/1318533267-18880-4-git-send-email-dzickus@redhat.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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A recent discussion started talking about the locking on the
pstore fs and how it relates to the kmsg infrastructure. We
noticed it was possible for userspace to r/w to the pstore fs
(grabbing the locks in the process) and block the panic path
from r/w to the same fs.
The reason was the cpu with the lock could be doing work while
the crashing cpu is panic'ing. Busting those spinlocks might
cause those cpus to step on each other's data. Fine, fair
enough.
It was suggested it would be nice to serialize the panic path
(ie stop the other cpus) and have only one cpu running. This
would allow us to bust the spinlocks and not worry about another
cpu stepping on the data.
Of course, smp_send_stop() does this in the panic case.
kmsg_dump() would have to be moved to be called after it. Easy
enough.
The only problem is on x86 the smp_send_stop() function calls
the REBOOT_VECTOR. Any cpu with irqs disabled (which pstore and
its backend ERST would do), block this IPI and thus do not stop.
This makes it difficult to reliably log data to the pstore fs.
The patch below switches from the REBOOT_VECTOR to NMI (and
mimics what kdump does). Switching to NMI allows us to deliver
the IPI when irqs are disabled, increasing the reliability of
this function.
However, Andi carefully noted that on some machines this
approach does not work because of broken BIOSes or whatever.
To help accomodate this, the next couple of patches will run a
selftest and provide a knob to disable.
V2:
uses atomic ops to serialize the cpu that shuts everyone down
V3:
comment cleanup
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <robert.richter@amd.com>
Cc: seiji.aguchi@hds.com
Cc: vgoyal@redhat.com
Cc: mjg@redhat.com
Cc: tony.luck@intel.com
Cc: gong.chen@intel.com
Cc: satoru.moriya@hds.com
Cc: avi@redhat.com
Cc: Andi Kleen <andi@firstfloor.org>
Link: http://lkml.kernel.org/r/1318533267-18880-2-git-send-email-dzickus@redhat.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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These files were implicitly getting EXPORT_SYMBOL via device.h
which was including module.h, but that will be fixed up shortly.
By fixing these now, we can avoid seeing things like:
arch/x86/kernel/rtc.c:29: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’
arch/x86/kernel/pci-dma.c:20: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’
arch/x86/kernel/e820.c:69: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL_GPL’
[ with input from Randy Dunlap <rdunlap@xenotime.net> and also
from Stephen Rothwell <sfr@canb.auug.org.au> ]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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For future rework of try_to_wake_up() we'd like to push part of that
function onto the CPU the task is actually going to run on.
In order to do so we need a generic callback from the existing scheduler IPI.
This patch introduces such a generic callback: scheduler_ipi() and
implements it as a NOP.
BenH notes: PowerPC might use this IPI on offline CPUs under rare conditions!
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110405152728.744338123@chello.nl
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x86 smp_ops now has a new op, stop_other_cpus which takes a parameter
"wait" this allows the caller to specify if it wants to stop until all
the cpus have processed the stop IPI. This is required specifically
for the kexec case where we should wait for all the cpus to be stopped
before starting the new kernel. We now wait for the cpus to stop in
all cases except for panic/kdump where we expect things to be broken
and we are doing our best to make things work anyway.
This patch fixes a legitimate regression, which was introduced during
2.6.30, by commit id 4ef702c10b5df18ab04921fc252c26421d4d6c75.
Signed-off-by: Alok N Kataria <akataria@vmware.com>
LKML-Reference: <1286833028.1372.20.camel@ank32.eng.vmware.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: <stable@kernel.org> v2.6.30-36
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
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This reverts commit 9bcbdd9c58617f1301dd4f17c738bb9bc73aca70.
The real bug producing LatencyTop latencies has been fixed in:
f5dc375: sched: Update the clock of runqueue select_task_rq() selected
And the commit being reverted here triggers local timer processing
from every device IRQ. If device IRQs come in at a high frequency,
this could cause a performance regression.
The commit being reverted here purely 'fixed' the reported latency
as a side effect, because CPUs were being moved out of idle more
often.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Frans Pop <elendil@planet.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <20091008064041.67219b13@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Now that range timers and deferred timers are common, I found a
problem with these using the "perf timechart" tool. Frans Pop also
reported high scheduler latencies via LatencyTop, when using
iwlagn.
It turns out that on x86, these two 'opportunistic' timers only get
checked when another "real" timer happens. These opportunistic
timers have the objective to save power by hitchhiking on other
wakeups, as to avoid CPU wakeups by themselves as much as possible.
The change in this patch runs this check not only at timer
interrupts, but at all (device) interrupts. The effect is that:
1) the deferred timers/range timers get delayed less
2) the range timers cause less wakeups by themselves because
the percentage of hitchhiking on existing wakeup events goes up.
I've verified the working of the patch using "perf timechart", the
original exposed bug is gone with this patch. Frans also reported
success - the latencies are now down in the expected ~10 msec
range.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Tested-by: Frans Pop <elendil@planet.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091008064041.67219b13@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Conflicts:
arch/x86/kernel/cpu/mcheck/mce_64.c
arch/x86/kernel/irq.c
Merge reason: Resolve the conflicts above.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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* 'kvm-updates/2.6.31' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (138 commits)
KVM: Prevent overflow in largepages calculation
KVM: Disable large pages on misaligned memory slots
KVM: Add VT-x machine check support
KVM: VMX: Rename rmode.active to rmode.vm86_active
KVM: Move "exit due to NMI" handling into vmx_complete_interrupts()
KVM: Disable CR8 intercept if tpr patching is active
KVM: Do not migrate pending software interrupts.
KVM: inject NMI after IRET from a previous NMI, not before.
KVM: Always request IRQ/NMI window if an interrupt is pending
KVM: Do not re-execute INTn instruction.
KVM: skip_emulated_instruction() decode instruction if size is not known
KVM: Remove irq_pending bitmap
KVM: Do not allow interrupt injection from userspace if there is a pending event.
KVM: Unprotect a page if #PF happens during NMI injection.
KVM: s390: Verify memory in kvm run
KVM: s390: Sanity check on validity intercept
KVM: s390: Unlink vcpu on destroy - v2
KVM: s390: optimize float int lock: spin_lock_bh --> spin_lock
KVM: s390: use hrtimer for clock wakeup from idle - v2
KVM: s390: Fix memory slot versus run - v3
...
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KVM uses a function call IPI to cause the exit of a guest running on a
physical cpu. For virtual interrupt notification there is no need to
wait on IPI receival, or to execute any function.
This is exactly what the reschedule IPI does, without the overhead
of function IPI. So use it instead of smp_call_function_single in
kvm_vcpu_kick.
Also change the "guest_mode" variable to a bit in vcpu->requests, and
use that to collapse multiple IPI's that would be issued between the
first one and zeroing of guest mode.
This allows kvm_vcpu_kick to called with interrupts disabled.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
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For some time each panic() called with interrupts disabled
triggered the !irqs_disabled() WARN_ON in smp_call_function(),
producing ugly backtraces and confusing users.
This is a common situation with machine checks for example which
tend to call panic with interrupts disabled, but will also hit
in other situations e.g. panic during early boot. In fact it
means that panic cannot be called in many circumstances, which
would be bad.
This all started with the new fancy queued smp_call_function,
which is then used by the shutdown path to shut down the other
CPUs.
On closer examination it turned out that the fancy RCU
smp_call_function() does lots of things not suitable in a panic
situation anyways, like allocating memory and relying on complex
system state.
I originally tried to patch this over by checking for panic
there, but it was quite complicated and the original patch
was also not very popular. This also didn't fix some of the
underlying complexity problems.
The new code in post 2.6.29 tries to patch around this by
checking for oops_in_progress, but that is not enough to make
this fully safe and I don't think that's a real solution
because panic has to be reliable.
So instead use an own vector to reboot. This makes the reboot
code extremly straight forward, which is definitely a big plus
in a panic situation where it is important to avoid relying on
too much kernel state. The new simple code is also safe to be
called from interupts off region because it is very very simple.
There can be situations where it is important that panic
is reliable. For example on a fatal machine check the panic
is needed to get the system up again and running as quickly
as possible. So it's important that panic is reliable and
all function it calls simple.
This is why I came up with this simple vector scheme.
It's very hard to beat in simplicity. Vectors are not
particularly precious anymore since all big systems are
using per CPU vectors.
Another possibility would have been to use an NMI similar
to kdump, but there is still the problem that NMIs don't
work reliably on some systems due to BIOS issues. NMIs
would have been able to stop CPUs running with interrupts
off too. In the sake of universal reliability I opted for
using a non NMI vector for now.
I put the reboot vector into the highest priority bucket of
the APIC vectors and moved the 64bit UV_BAU message down
instead into the next lower priority.
[ Impact: bug fix, fixes an old regression ]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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Impact: cleanup
It's a bit hard to parse by eyes without
them being aligned.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
LKML-Reference: <20090412165058.924175574@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: cleanup
Remove genapic.h and remove all references to it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Move mach_ipi.h definitions into genapic.h.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Spread mach_apic.h definitions into genapic.h. (with some knock-on effects
on smp.h and apic.h.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Our send_IPI_*() methods and definitions are a twisted mess: the same
symbol is defined to different things depending on .config details,
in a non-transparent way.
- spread out the quirks into separately named per apic driver methods
- prefix the standard PC methods with default_
- get rid of wrapper macro obfuscation
- clean up various details
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (36 commits)
x86: fix section mismatch warnings in mcheck/mce_amd_64.c
x86: offer frame pointers in all build modes
x86: remove duplicated #include's
x86: k8 numa register active regions later
x86: update Alan Cox's email addresses
x86: rename all fields of mpc_table mpc_X to X
x86: rename all fields of mpc_oemtable oem_X to X
x86: rename all fields of mpc_bus mpc_X to X
x86: rename all fields of mpc_cpu mpc_X to X
x86: rename all fields of mpc_intsrc mpc_X to X
x86: rename all fields of mpc_lintsrc mpc_X to X
x86: rename all fields of mpc_iopic mpc_X to X
x86: irqinit_64.c init_ISA_irqs should be static
Documentation/x86/boot.txt: payload length was changed to payload_length
x86: setup_percpu.c fix style problems
x86: irqinit_64.c fix style problems
x86: irqinit_32.c fix style problems
x86: i8259.c fix style problems
x86: irq_32.c fix style problems
x86: ioport.c fix style problems
...
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Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: use new cpumask API to reduce memory and stack usage
Allocate the following local cpumasks based on the number of cpus that
are present. References will use new cpumask API. (Currently only
modified for x86_64, x86_32 continues to use the *_map variants.)
cpu_callin_mask
cpu_callout_mask
cpu_initialized_mask
cpu_sibling_setup_mask
Provide the following accessor functions:
struct cpumask *cpu_sibling_mask(int cpu)
struct cpumask *cpu_core_mask(int cpu)
Other changes are when setting or clearing the cpu online, possible
or present maps, use the accessor functions.
Signed-off-by: Mike Travis <travis@sgi.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* '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
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This patch simply changes cpumask_t to struct cpumask and similar
trivial modernizations.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
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Impact: cleanup, change parameter passing
* Change genapic interfaces to accept cpumask_t pointers where possible.
* Modify external callers to use cpumask_t pointers in function calls.
* Create new send_IPI_mask_allbutself which is the same as the
send_IPI_mask functions but removes smp_processor_id() from list.
This removes another common need for a temporary cpumask_t variable.
* Functions that used a temp cpumask_t variable for:
cpumask_t allbutme = cpu_online_map;
cpu_clear(smp_processor_id(), allbutme);
if (!cpus_empty(allbutme))
...
become:
if (!cpus_equal(cpu_online_map, cpumask_of_cpu(cpu)))
...
* Other minor code optimizations (like using cpus_clear instead of
CPU_MASK_NONE, etc.)
Applies to linux-2.6.tip/master.
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Ingo Molnar <mingo@elte.hu>
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Impact: cleanup
Introduce inc_irq_stat() macro and unify irq_stat accounting code.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: really halt all CPUs on halt
Function machine_halt (resp. native_machine_halt) is empty for x86
architectures. When command 'halt -f' is invoked, the message "System
halted." is displayed but this is not really true because all CPUs are
still running.
There are also similar inconsistencies for other arches (some uses
power-off for halt or forever-loop with IRQs enabled/disabled).
IMO there should be used the same approach for all architectures OR
what does the message "System halted" really mean?
This patch fixes it for x86.
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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create proper stackframe.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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It's never used and the comments refer to nonatomic and retry
interchangably. So get rid of it.
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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This converts x86, x86-64, and xen to use the new helpers for
smp_call_function() and friends, and adds support for
smp_call_function_single().
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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After resume on a 2cpu laptop, kernel builds collapse with a sed hang,
sh or make segfault (often on 20295564), real-time signal to cc1 etc.
Several hurdles to jump, but a manually-assisted bisect led to -rc1's
d2bcbad5f3ad38a1c09861bca7e252dde7bb8259 x86: do not zap_low_mappings
in __smp_prepare_cpus. Though the low mappings were removed at bootup,
they were left behind (with Global flags helping to keep them in TLB)
after resume or cpu online, causing the crashes seen.
Reinstate zap_low_mappings (with local __flush_tlb_all) for each cpu_up
on x86_32. This used to be serialized by smp_commenced_mask: that's now
gone, but a low_mappings flag will do. No need for native_smp_cpus_done
to repeat the zap: let mem_init zap BSP's low mappings just like on UP.
(In passing, fix error code from native_cpu_up: do_boot_cpu returns a
variety of diagnostic values, Dprintk what it says but convert to -EIO.
And save_pg_dir separately before zap_low_mappings: doesn't matter now,
but zapping twice in succession wiped out resume's swsusp_pg_dir.)
That worked well on the duo and one quad, but wouldn't boot 3rd or 4th
cpu on P4 Xeon, oopsing just after unlock_ipi_call_lock. The TLB flush
IPI now being sent reveals a long-standing bug: the booting cpu has its
APIC readied in smp_callin at the top of start_secondary, but isn't put
into the cpu_online_map until just before that unlock_ipi_call_lock.
So native_smp_call_function_mask to online cpus would send_IPI_allbutself,
including the cpu just coming up, though it has been excluded from the
count to wait for: by the time it handles the IPI, the call data on
native_smp_call_function_mask's stack may well have been overwritten.
So fall back to send_IPI_mask while cpu_online_map does not match
cpu_callout_map: perhaps there's a better APICological fix to be
made at the start_secondary end, but I wouldn't know that.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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take them out of the x86_64-only asm/mach_apic.h
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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In the x86 native_smp_send_reschedule_function(), don't send the IPI if the
cpu has gone offline already. Warn nevertheless!!
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This patch merges the copyright notices, and valuable
comments that were left back on smp_{32,64}.c. With that,
files are empty, and are deleted
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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this patch moves all the functions and data structures that look
like exactly the same from smp_{32,64}.c to smp.c
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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