From: Borislav Petkov <b...@suse.de>
With some microcode upgrades, new CPUID features can become visible on
the CPU. Check what the kernel has mirrored now and issue a warning
hinting at possible things the user/admin can do to make use of the
newly visible features.
Originally-by: Ashok Raj <ashok....@intel.com>
Signed-off-by: Borislav Petkov <b...@suse.de>
---
arch/x86/kernel/cpu/common.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 82c142b33bf3..768eb680db8d 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1757,5 +1757,25 @@ core_initcall(init_cpu_syscore);
*/
void microcode_check(void)
{
+ struct cpuinfo_x86 info;
+
perf_check_microcode();
+
+ /* Reload CPUID max function as it might've changed. */
+ info.cpuid_level = cpuid_eax(0);
+
+ /*
+ * Copy all capability leafs to pick up the synthetic ones so that
+ * memcmp() below doesn't fail on that. The ones coming from CPUID will
+ * get overwritten in get_cpu_cap().
+ */
+ memcpy(&info.x86_capability, &boot_cpu_data.x86_capability,
sizeof(info.x86_capability));
+
+ get_cpu_cap(&info);
+
+ if (!memcmp(&info.x86_capability, &boot_cpu_data.x86_capability,
sizeof(info.x86_capability)))
+ return;
+
+ pr_warn("x86/CPU: CPU features have changed after loading microcode,
but might not take effect.\n");
+ pr_warn("x86/CPU: Please consider either early loading through
initrd/built-in or a potential BIOS update.\n");
}
--
2.13.0
