Verified using the below proglet.. before:

[root@westmere ~]# perf stat -e node-stores -e node-store-misses ./numa 0
remote write

 Performance counter stats for './numa 0':

         2,101,554 node-stores
         2,096,931 node-store-misses

       5.021546079 seconds time elapsed

[root@westmere ~]# perf stat -e node-stores -e node-store-misses ./numa 1
local write

 Performance counter stats for './numa 1':

           501,137 node-stores
               199 node-store-misses

       5.124451068 seconds time elapsed

After:

[root@westmere ~]# perf stat -e node-stores -e node-store-misses ./numa 0
remote write

 Performance counter stats for './numa 0':

         2,107,516 node-stores
         2,097,187 node-store-misses

       5.012755149 seconds time elapsed

[root@westmere ~]# perf stat -e node-stores -e node-store-misses ./numa 1
local write

 Performance counter stats for './numa 1':

         2,063,355 node-stores
               165 node-store-misses

       5.082091494 seconds time elapsed

#define _GNU_SOURCE

#include <sched.h>
#include <stdio.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <dirent.h>
#include <signal.h>
#include <unistd.h>
#include <numaif.h>
#include <stdlib.h>

#define SIZE (32*1024*1024)

volatile int done;

void sig_done(int sig)
{
	done = 1;
}

int main(int argc, char **argv)
{
	cpu_set_t *mask, *mask2;
	size_t size;
	int i, err, t;
	int nrcpus = 1024;
	char *mem;
	unsigned long nodemask = 0x01; /* node 0 */
	DIR *node;
	struct dirent *de;
	int read = 0;
	int local = 0;

	if (argc < 2) {
		printf("usage: %s [0-3]\n", argv[0]);
		printf("  bit0 - local/remote\n");
		printf("  bit1 - read/write\n");
		exit(0);
	}

	switch (atoi(argv[1])) {
	case 0:
		printf("remote write\n");
		break;
	case 1:
		printf("local write\n");
		local = 1;
		break;
	case 2:
		printf("remote read\n");
		read = 1;
		break;
	case 3:
		printf("local read\n");
		local = 1;
		read = 1;
		break;
	}

	mask = CPU_ALLOC(nrcpus);
	size = CPU_ALLOC_SIZE(nrcpus);
	CPU_ZERO_S(size, mask);

	node = opendir("/sys/devices/system/node/node0/");
	if (!node)
		perror("opendir");
	while ((de = readdir(node))) {
		int cpu;

		if (sscanf(de->d_name, "cpu%d", &cpu) == 1)
			CPU_SET_S(cpu, size, mask);
	}
	closedir(node);

	mask2 = CPU_ALLOC(nrcpus);
	CPU_ZERO_S(size, mask2);
	for (i = 0; i < size; i++)
		CPU_SET_S(i, size, mask2);
	CPU_XOR_S(size, mask2, mask2, mask); // invert

	if (!local)
		mask = mask2;

	err = sched_setaffinity(0, size, mask);
	if (err)
		perror("sched_setaffinity");

	mem = mmap(0, SIZE, PROT_READ|PROT_WRITE,
			MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
	err = mbind(mem, SIZE, MPOL_BIND, &nodemask, 8*sizeof(nodemask), MPOL_MF_MOVE);
	if (err)
		perror("mbind");

	signal(SIGALRM, sig_done);
	alarm(5);

	if (!read) {
		while (!done) {
			for (i = 0; i < SIZE; i++)
				mem[i] = 0x01;
		}
	} else {
		while (!done) {
			for (i = 0; i < SIZE; i++)
				t += *(volatile char *)(mem + i);
		}
	}

	return 0;
}

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/n/tip-tq73sxus35xmqpojf7ootxgs@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>

It turned out that a performance counter on AMD does not
count at all when the GO or HO bit is set in the control
register and SVM is disabled in EFER.

This patch works around this issue by masking out the HO bit
in the performance counter control register when SVM is not
enabled.

The GO bit is not touched because it is only set when the
user wants to count in guest-mode only. So when SVM is
disabled the counter should not run at all and the
not-counting is the intended behaviour.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Avi Kivity <avi@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: stable@vger.kernel.org # v3.2
Link: http://lkml.kernel.org/r/1330523852-19566-1-git-send-email-joerg.roedel@amd.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce/AMD: Fix UP build error
  x86: Specify a size for the cmp in the NMI handler
  x86/nmi: Test saved %cs in NMI to determine nested NMI case
  x86/amd: Fix L1i and L2 cache sharing information for AMD family 15h processors
  x86/microcode: Remove noisy AMD microcode warning

141168c36cde ("x86: Simplify code by removing a !SMP #ifdefs
from 'struct cpuinfo_x86'") removed a bunch of CONFIG_SMP ifdefs
around code touching struct cpuinfo_x86 members but also caused
the following build error with Randy's randconfigs:

mce_amd.c:(.cpuinit.text+0x4723): undefined reference to `cpu_llc_shared_map'

Restore the #ifdef in threshold_create_bank() which creates
symlinks on the non-BSP CPUs.

There's a better patch series being worked on by Kevin Winchester
which will solve this in a cleaner fashion, but that series is
too ambitious for v3.3 merging - so we first queue up this trivial
fix and then do the rest for v3.4.

Signed-off-by: Borislav Petkov <bp@alien8.de>
Acked-by: Kevin Winchester <kjwinchester@gmail.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Nick Bowler <nbowler@elliptictech.com>
Link: http://lkml.kernel.org/r/20120203191801.GA2846@x1.osrc.amd.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

(And define it properly for x86-32, which had its 'current_task'
declaration in separate from x86-64)

Bitten by my dislike for modules on the machines I use, and the fact
that apparently nobody else actually wanted to test the patches I sent
out.

Snif. Nobody else cares.

Anyway, we probably should uninline the 'kernel_fpu_begin()' function
that is what modules actually use and that references this, but this is
the minimal fix for now.

Reported-by: Josh Boyer <jwboyer@gmail.com>
Reported-and-tested-by: Jongman Heo <jongman.heo@samsung.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Linus noticed that the cmp used to check if the code segment is
__KERNEL_CS or not did not specify a size. Perhaps it does not matter
as H. Peter Anvin noted that user space can not set the bottom two
bits of the %cs register. But it's best not to let the assembly choose
and change things between different versions of gas, but instead just
pick the size.

Four bytes are used to compare the saved code segment against
__KERNEL_CS. Perhaps this might mess up Xen, but we can fix that when
the time comes.

Also I noticed that there was another non-specified cmp that checks
the special stack variable if it is 1 or 0. This too probably doesn't
matter what cmp is used, but this patch uses cmpl just to make it non
ambiguous.

Link: http://lkml.kernel.org/r/CA+55aFxfAn9MWRgS3O5k2tqN5ys1XrhSFVO5_9ZAoZKDVgNfGA@mail.gmail.com

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

This makes us recognize when we try to restore FPU state that matches
what we already have in the FPU on this CPU, and avoids the restore
entirely if so.

To do this, we add two new data fields:

 - a percpu 'fpu_owner_task' variable that gets written any time we
   update the "has_fpu" field, and thus acts as a kind of back-pointer
   to the task that owns the CPU.  The exception is when we save the FPU
   state as part of a context switch - if the save can keep the FPU
   state around, we leave the 'fpu_owner_task' variable pointing at the
   task whose FP state still remains on the CPU.

 - a per-thread 'last_cpu' field, that indicates which CPU that thread
   used its FPU on last.  We update this on every context switch
   (writing an invalid CPU number if the last context switch didn't
   leave the FPU in a lazily usable state), so we know that *that*
   thread has done nothing else with the FPU since.

These two fields together can be used when next switching back to the
task to see if the CPU still matches: if 'fpu_owner_task' matches the
task we are switching to, we know that no other task (or kernel FPU
usage) touched the FPU on this CPU in the meantime, and if the current
CPU number matches the 'last_cpu' field, we know that this thread did no
other FP work on any other CPU, so the FPU state on the CPU must match
what was saved on last context switch.

In that case, we can avoid the 'f[x]rstor' entirely, and just clear the
CR0.TS bit.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This inlines what is usually just a couple of instructions, but more
importantly it also fixes the theoretical error case (can that FPU
restore really ever fail? Maybe we should remove the checking).

We can't start sending signals from within the scheduler, we're much too
deep in the kernel and are holding the runqueue lock etc.  So don't
bother even trying.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This makes sure we clear the FPU usage counter for newly created tasks,
just so that we start off in a known state (for example, don't try to
preload the FPU state on the first task switch etc).

It also fixes a thinko in when we increment the fpu_counter at task
switch time, introduced by commit 34ddc81a230b ("i387: re-introduce FPU
state preloading at context switch time").  We should increment the
*new* task fpu_counter, not the old task, and only if we decide to use
that state (whether lazily or preloaded).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Currently, the NMI handler tests if it is nested by checking the
special variable saved on the stack (set during NMI handling)
and whether the saved stack is the NMI stack as well (to prevent
the race when the variable is set to zero).

But userspace may set their %rsp to any value as long as they do
not derefence it, and it may make it point to the NMI stack,
which will prevent NMIs from triggering while the userspace app
is running. (I tested this, and it is indeed the case)

Add another check to determine nested NMIs by looking at the
saved %cs (code segment register) and making sure that it is the
kernel code segment.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/r/1329687817.1561.27.camel@acer.local.home
Signed-off-by: Ingo Molnar <mingo@elte.hu>