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

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
This commit is contained in:
Ashok Raj 2018-02-28 11:28:43 +01:00 committed by Thomas Gleixner
parent 91df9fdf51
commit 30ec26da99
1 changed files with 18 additions and 0 deletions
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18
arch/x86/kernel/cpu/microcode/core.c
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@ -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)