Commit 760f9488 authored Feb 28, 2018 by Ashok Raj Committed by Greg Kroah-Hartman Aug 15, 2018

x86/microcode: Do not upload microcode if CPUs are offline



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.com
Link: https://lkml.kernel.org/r/20180228102846.13447-5-bp@alien8.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent d21c2718

arch/x86/kernel/cpu/microcode/core.c

+18 −0

Original line number	Diff line number	Diff line
		@@ -384,6 +384,16 @@ static void __exit microcode_dev_exit(void)
		/* 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 int reload_for_cpu(int cpu)
		{
		struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
		@@ -418,7 +428,13 @@ static ssize_t reload_store(struct device *dev,
		return size;

		get_online_cpus();

		ret = check_online_cpus();
		if (ret)
		goto put;

		mutex_lock(&microcode_mutex);

		for_each_online_cpu(cpu) {
		tmp_ret = reload_for_cpu(cpu);
		if (tmp_ret != 0)
		@@ -431,6 +447,8 @@ static ssize_t reload_store(struct device *dev,
		if (!ret)
		perf_check_microcode();
		mutex_unlock(&microcode_mutex);

		put:
		put_online_cpus();

		if (!ret)