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| author | Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> | 2011-10-09 15:42:00 -0400 |
|---|---|---|
| committer | Borislav Petkov <borislav.petkov@amd.com> | 2011-10-13 16:20:35 +0200 |
| commit | 70989449daccf545214b4840b112558e25c2b3fc (patch) | |
| tree | 60aef1f69d98cd7e1ef4ee5d1fe15ffd2cdbae9f /arch/x86 | |
| parent | 37cf95162af4036b4198756a590aab8126fa2ce4 (diff) | |
| download | linux-stable-70989449daccf545214b4840b112558e25c2b3fc.tar.gz linux-stable-70989449daccf545214b4840b112558e25c2b3fc.tar.bz2 linux-stable-70989449daccf545214b4840b112558e25c2b3fc.zip | |
x86, microcode: Don't request microcode from userspace unnecessarily
Requesting the microcode from userspace *every time* when onlining CPUs
(during a CPU hotplug operation) is unnecessary. Thus, ensure that
once the kernel gets the microcode after booting, it is not freed nor
invalidated when a CPU goes offline, so that it can be reused when that
CPU comes back online, without requesting userspace for it again. As a
result, the CPU hotplug operations become faster as well.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Link: http://lkml.kernel.org/r/4E91F908.5010006@linux.vnet.ibm.com
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/microcode_core.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/x86/kernel/microcode_core.c b/arch/x86/kernel/microcode_core.c index f9242800bc84..f2d2a664e797 100644 --- a/arch/x86/kernel/microcode_core.c +++ b/arch/x86/kernel/microcode_core.c @@ -483,7 +483,13 @@ mc_cpu_callback(struct notifier_block *nb, unsigned long action, void *hcpu) sysfs_remove_group(&sys_dev->kobj, &mc_attr_group); pr_debug("CPU%d removed\n", cpu); break; - case CPU_DEAD: + + /* + * When a CPU goes offline, don't free up or invalidate the copy of + * the microcode in kernel memory, so that we can reuse it when the + * CPU comes back online without unnecessarily requesting the userspace + * for it again. + */ case CPU_UP_CANCELED_FROZEN: /* The CPU refused to come up during a system resume */ microcode_fini_cpu(cpu); |