Commit 91df9fdf authored Feb 28, 2018 by Ashok Raj Committed by Thomas Gleixner Mar 08, 2018

x86/microcode/intel: Writeback and invalidate caches before updating microcode



Updating microcode is less error prone when caches have been flushed and
depending on what exactly the microcode is updating. For example, some
of the issues around certain Broadwell parts can be addressed by doing a
full cache flush.

[ Borislav: Massage it and use native_wbinvd() in both cases. ]

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>
Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com>
Link: http://lkml.kernel.org/r/1519352533-15992-3-git-send-email-ashok.raj@intel.com
Link: https://lkml.kernel.org/r/20180228102846.13447-4-bp@alien8.de

parent c182d2b7

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

+12 −0

Original line number	Diff line number	Diff line
		@@ -600,6 +600,12 @@ static int apply_microcode_early(struct ucode_cpu_info *uci, bool early)
		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);

		@@ -816,6 +822,12 @@ static enum ucode_state apply_microcode_intel(int cpu)
		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 */
		wrmsrl(MSR_IA32_UCODE_WRITE, (unsigned long)mc->bits);