x86/microcode: Do not upload microcode if CPUs are offline (30ec26da) · Commits · e / devices / android_kernel_teracube_emerald

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

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

+18 −0

Original line number	Diff line number	Diff line
		@@ -486,6 +486,16 @@ 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 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 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 > UCODE_NFOUND) {
		@@ -538,6 +554,8 @@ static ssize_t reload_store(struct device *dev,
		microcode_check();

		mutex_unlock(&microcode_mutex);

		put:
		put_online_cpus();

		if (!ret)