4.9-stable review patch. If anyone has any objections, please let me know.
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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 Signed-off-by: David Woodhouse dwmw@amazon.co.uk 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 @@ -384,6 +384,16 @@ 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 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 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 != 0) @@ -431,6 +447,8 @@ static ssize_t reload_store(struct devic if (!ret) perf_check_microcode(); mutex_unlock(µcode_mutex); + +put: put_online_cpus();
if (!ret)