Commit ab713e70 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86_microcode_for_v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 microcode loader update from Borislav Petkov:

 - Remove the unconditional cache writeback and invalidation after
   loading the microcode patch on Intel as this was addressing a
   microcode bug for which there is a concrete microcode revision check
   instead

* tag 'x86_microcode_for_v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/microcode/intel: Remove unnecessary cache writeback and invalidation
parents 5a4b3fbb 9a819753

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

+2 −8
Original line number Diff line number Diff line
@@ -319,12 +319,6 @@ static enum ucode_state __apply_microcode(struct ucode_cpu_info *uci, 
		return UCODE_OK;

	}



	/*

	 * Writeback and invalidate caches before updating microcode to avoid

	 * internal issues depending on what the microcode is updating.

	 */

	native_wbinvd();



	/* write microcode via MSR 0x79 */

	native_wrmsrl(MSR_IA32_UCODE_WRITE, (unsigned long)mc->bits);
@@ -574,14 +568,14 @@ static bool is_blacklisted(unsigned int cpu) 
	/*

	 * Late loading on model 79 with microcode revision less than 0x0b000021

	 * and LLC size per core bigger than 2.5MB may result in a system hang.

	 * This behavior is documented in item BDF90, #334165 (Intel Xeon

	 * This behavior is documented in item BDX90, #334165 (Intel Xeon

	 * Processor E7-8800/4800 v4 Product Family).

	 */

	if (c->x86_vfm == INTEL_BROADWELL_X &&

	    c->x86_stepping == 0x01 &&

	    llc_size_per_core > 2621440 &&

	    c->microcode < 0x0b000021) {

		pr_err_once("Erratum BDF90: late loading with revision < 0x0b000021 (0x%x) disabled.\n", c->microcode);

		pr_err_once("Erratum BDX90: late loading with revision < 0x0b000021 (0x%x) disabled.\n", c->microcode);

		pr_err_once("Please consider either early loading through initrd/built-in or a potential BIOS update.\n");

		return true;

	}