This is a note to let you know that I've just added the patch titled
x86/microcode: Do not upload microcode if CPUs are offline
to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: x86-microcode-do-not-upload-microcode-if-cpus-are-offline.patch and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 30ec26da9967d0d785abc24073129a34c3211777 Mon Sep 17 00:00:00 2001
From: Ashok Raj ashok.raj@intel.com Date: Wed, 28 Feb 2018 11:28:43 +0100 Subject: x86/microcode: Do not upload microcode if CPUs are offline
From: Ashok Raj ashok.raj@intel.com
commit 30ec26da9967d0d785abc24073129a34c3211777 upstream.
Avoid loading microcode if any of the CPUs are offline, and issue a warning. Having different microcode revisions on the system at any time is outright dangerous.
[ Borislav: Massage changelog. ]
Signed-off-by: Ashok Raj ashok.raj@intel.com Signed-off-by: Borislav Petkov bp@suse.de Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Tom Lendacky thomas.lendacky@amd.com Tested-by: Ashok Raj ashok.raj@intel.com Reviewed-by: Tom Lendacky thomas.lendacky@amd.com Cc: Arjan Van De Ven arjan.van.de.ven@intel.com Link: http://lkml.kernel.org/r/1519352533-15992-4-git-send-email-ashok.raj@intel.c... Link: https://lkml.kernel.org/r/20180228102846.13447-5-bp@alien8.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kernel/cpu/microcode/core.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)
--- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -486,6 +486,16 @@ static void __exit microcode_dev_exit(vo /* fake device for request_firmware */ static struct platform_device *microcode_pdev;
+static int check_online_cpus(void) +{ + if (num_online_cpus() == num_present_cpus()) + return 0; + + pr_err("Not all CPUs online, aborting microcode update.\n"); + + return -EINVAL; +} + static enum ucode_state reload_for_cpu(int cpu) { struct ucode_cpu_info *uci = ucode_cpu_info + cpu; @@ -519,7 +529,13 @@ static ssize_t reload_store(struct devic return size;
get_online_cpus(); + + ret = check_online_cpus(); + if (ret) + goto put; + mutex_lock(µcode_mutex); + for_each_online_cpu(cpu) { tmp_ret = reload_for_cpu(cpu); if (tmp_ret > UCODE_NFOUND) { @@ -538,6 +554,8 @@ static ssize_t reload_store(struct devic microcode_check();
mutex_unlock(µcode_mutex); + +put: put_online_cpus();
if (!ret)
Patches currently in stable-queue which might be from ashok.raj@intel.com are
queue-4.15/x86-microcode-intel-check-microcode-revision-before-updating-sibling-threads.patch queue-4.15/x86-microcode-attempt-late-loading-only-when-new-microcode-is-present.patch queue-4.15/x86-microcode-propagate-return-value-from-updating-functions.patch queue-4.15/x86-cpu-check-cpu-feature-bits-after-microcode-upgrade.patch queue-4.15/x86-microcode-intel-writeback-and-invalidate-caches-before-updating-microcode.patch queue-4.15/x86-microcode-intel-look-into-the-patch-cache-first.patch queue-4.15/x86-microcode-request-microcode-on-the-bsp.patch queue-4.15/x86-microcode-get-rid-of-struct-apply_microcode_ctx.patch queue-4.15/x86-microcode-fix-cpu-synchronization-routine.patch queue-4.15/x86-microcode-synchronize-late-microcode-loading.patch queue-4.15/x86-microcode-do-not-upload-microcode-if-cpus-are-offline.patch queue-4.15/x86-cpu-add-a-microcode-loader-callback.patch