diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2023-10-17 23:24:16 +0200 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-10-24 15:05:55 +0200 |
| commit | 9407bda845dd19756e276d4f3abc15a20777ba45 (patch) | |
| tree | 6bde9bdf4bacb4aedc78fbca49dad5dd0ed184e7 /arch/x86/kernel/cpu/microcode/intel.c | |
| parent | 8f849ff63bcbc77670da03cb8f2b78b06257f455 (diff) | |
x86/microcode: Prepare for minimal revision check
Applying microcode late can be fatal for the running kernel when the
update changes functionality which is in use already in a non-compatible
way, e.g. by removing a CPUID bit.
There is no way for admins which do not have access to the vendors deep
technical support to decide whether late loading of such a microcode is
safe or not.
Intel has added a new field to the microcode header which tells the
minimal microcode revision which is required to be active in the CPU in
order to be safe.
Provide infrastructure for handling this in the core code and a command
line switch which allows to enforce it.
If the update is considered safe the kernel is not tainted and the annoying
warning message not emitted. If it's enforced and the currently loaded
microcode revision is not safe for late loading then the load is aborted.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231017211724.079611170@linutronix.de
Diffstat (limited to 'arch/x86/kernel/cpu/microcode/intel.c')
| -rw-r--r-- | arch/x86/kernel/cpu/microcode/intel.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c index 905ed3b557fb..14aa4c6d4c14 100644 --- a/arch/x86/kernel/cpu/microcode/intel.c +++ b/arch/x86/kernel/cpu/microcode/intel.c @@ -480,6 +480,9 @@ static enum ucode_state parse_microcode_blobs(int cpu, struct iov_iter *iter) unsigned int curr_mc_size = 0; u8 *new_mc = NULL, *mc = NULL; + if (force_minrev) + return UCODE_NFOUND; + while (iov_iter_count(iter)) { struct microcode_header_intel mc_header; unsigned int mc_size, data_size; |