0124-x86-microcode-Force-update-a-uCode-even-if-the-rev-i.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Ashok Raj <ashok.raj@intel.com>
Date: Sat, 20 Jul 2019 14:14:47 +0000
Subject: [PATCH] x86/microcode: Force update a uCode even if the rev is the
 same

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
---
 arch/x86/kernel/cpu/microcode/core.c  |  1 +
 arch/x86/kernel/cpu/microcode/intel.c | 57 +++++++++++++++++++++++++--
 2 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 6a6318e9590c..fae61bd63ecf 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -604,6 +604,7 @@ static int microcode_reload_late(void)
 	atomic_set(&late_cpus_in,  0);
 	atomic_set(&late_cpus_out, 0);
 
+	printk ("Going to do stop_machine\n");
 	ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask);
 	if (ret == 0)
 		microcode_check();
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 7e8e07bddd5f..faaa56c05a64 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -30,6 +30,7 @@
 #include <linux/uio.h>
 #include <linux/mm.h>
 
+#include <asm/cmdline.h>
 #include <asm/microcode_intel.h>
 #include <asm/intel-family.h>
 #include <asm/processor.h>
@@ -38,6 +39,7 @@
 #include <asm/msr.h>
 
 static const char ucode_path[] = "kernel/x86/microcode/GenuineIntel.bin";
+static bool force_ucode_load = false;
 
 /* Current microcode patch used in early patching on the APs. */
 static struct microcode_intel *intel_ucode_patch;
@@ -94,8 +96,18 @@ static int has_newer_microcode(void *mc, unsigned int csig, int cpf, int new_rev
 {
 	struct microcode_header_intel *mc_hdr = mc;
 
-	if (mc_hdr->rev <= new_rev)
+	//if (mc_hdr->rev <= new_rev)
+	if (mc_hdr->rev < new_rev) {
+		printk ("Returning NO_NEW old = 0x%x new = 0x%x\n", 
+			mc_hdr->rev, new_rev);
 		return 0;
+	}
+	if ((mc_hdr->rev == new_rev) && !force_ucode_load) {
+		printk ("SAME REV: no_force Returning NO_NEW old = 0x%x new = 0x%x\n", 
+			mc_hdr->rev, new_rev);
+		return 0;
+	}
+	printk ("ucode: force loading same rev\n");
 
 	return find_matching_signature(mc, csig, cpf);
 }
@@ -550,11 +562,20 @@ static int apply_microcode_early(struct ucode_cpu_info *uci, bool early)
 	 * already.
 	 */
 	rev = intel_get_microcode_revision();
-	if (rev >= mc->hdr.rev) {
+	if (rev > mc->hdr.rev) {
 		uci->cpu_sig.rev = rev;
 		return UCODE_OK;
 	}
 
+	if (rev == mc->hdr.rev) {
+		if (!force_ucode_load) {
+			printk ("Matching ucode rev, no update\n");
+			return UCODE_OK;
+		} else {
+			printk ("Matching ucode rev.. force updating\n");
+		}
+	}
+
 	/*
 	 * Writeback and invalidate caches before updating microcode to avoid
 	 * internal issues depending on what the microcode is updating.
@@ -606,6 +627,29 @@ int __init save_microcode_in_initrd_intel(void)
 	return 0;
 }
 
+static bool check_force_ucode_bsp(void)
+{
+	static const char *__force_ucode_str = "force_ucode_load";
+
+#ifdef CONFIG_X86_32
+	const char *cmdline = (const char *)__pa_nodebug(boot_command_line);
+	const char *option  = (const char *)__pa_nodebug(__force_ucode_str);
+	bool *res = (bool *)__pa_nodebug(&force_ucode_load);
+
+#else /* CONFIG_X86_64 */
+	const char *cmdline = boot_command_line;
+	const char *option  = __force_ucode_str;
+	bool *res = &force_ucode_load;
+#endif
+
+	if (cmdline_find_option_bool(cmdline, option)) {
+		printk("cmdline forcing ucode update for same rev\n");
+		*res = true;
+	}
+
+	return *res;
+}
+
 /*
  * @res_patch, output: a pointer to the patch we found.
  */
@@ -639,6 +683,9 @@ void __init load_ucode_intel_bsp(void)
 {
 	struct microcode_intel *patch;
 	struct ucode_cpu_info uci;
+	bool force_bsp;
+
+	force_bsp = check_force_ucode_bsp();
 
 	patch = __load_ucode_intel(&uci);
 	if (!patch)
@@ -687,8 +734,12 @@ static struct microcode_intel *find_patch(struct ucode_cpu_info *uci)
 
 		phdr = (struct microcode_header_intel *)iter->data;
 
-		if (phdr->rev <= uci->cpu_sig.rev)
+		if (phdr->rev < uci->cpu_sig.rev)
 			continue;
+		if (phdr->rev == uci->cpu_sig.rev && !force_ucode_load)
+			continue;
+		else
+			printk ("same rev forcing ucode\n");
 
 		if (!find_matching_signature(phdr,
 					     uci->cpu_sig.sig,
-- 
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