[v2 02/13] x86/microcode/intel: Print old and new rev after early microcode update

[Ashok Raj]

Print the old and new versions of microcode after an early load is
complete. This is useful to know what version was loaded by BIOS before an
early microcode load.

Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Ashok Raj <ashok.raj@xxxxxxxxx>
---
v2:
 - (Boris) Fix microcode update message consistent for early and late.
 - apply_microcode_intel(): prev_rev isn't set until the first update.

 arch/x86/kernel/cpu/microcode/intel.c | 32 +++++++++++++++++----------
 1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 8f7f8dd6680e..733b5eac0444 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -435,10 +435,10 @@ static bool load_builtin_intel_microcode(struct cpio_data *cp)
  * Print ucode update info.
  */
 static void
-print_ucode_info(struct ucode_cpu_info *uci, unsigned int date)
+print_ucode_info(u32 old_rev, struct ucode_cpu_info *uci, unsigned int date)
 {
-	pr_info_once("microcode updated early to revision 0x%x, date = %04x-%02x-%02x\n",
-		     uci->cpu_sig.rev,
+	pr_info_once("early update: 0x%x -> 0x%x, date = %04x-%02x-%02x\n",
+		     old_rev, uci->cpu_sig.rev,
 		     date & 0xffff,
 		     date >> 24,
 		     (date >> 16) & 0xff);
@@ -448,6 +448,7 @@ print_ucode_info(struct ucode_cpu_info *uci, unsigned int date)
 
 static int delay_ucode_info;
 static int current_mc_date;
+static u32 early_old_rev;
 
 /*
  * Print early updated ucode info after printk works. This is delayed info dump.
@@ -458,7 +459,7 @@ void show_ucode_info_early(void)
 
 	if (delay_ucode_info) {
 		intel_cpu_collect_info(&uci);
-		print_ucode_info(&uci, current_mc_date);
+		print_ucode_info(early_old_rev, &uci, current_mc_date);
 		delay_ucode_info = 0;
 	}
 }
@@ -467,11 +468,12 @@ void show_ucode_info_early(void)
  * At this point, we can not call printk() yet. Delay printing microcode info in
  * show_ucode_info_early() until printk() works.
  */
-static void print_ucode(struct ucode_cpu_info *uci)
+static void print_ucode(u32 old_rev, struct ucode_cpu_info *uci)
 {
 	struct microcode_intel *mc;
 	int *delay_ucode_info_p;
 	int *current_mc_date_p;
+	u32 *old_rev_p;
 
 	mc = uci->mc;
 	if (!mc)
@@ -479,13 +481,15 @@ static void print_ucode(struct ucode_cpu_info *uci)
 
 	delay_ucode_info_p = (int *)__pa_nodebug(&delay_ucode_info);
 	current_mc_date_p = (int *)__pa_nodebug(&current_mc_date);
+	old_rev_p = (u32 *)__pa_nodebug(&early_old_rev);
 
 	*delay_ucode_info_p = 1;
 	*current_mc_date_p = mc->hdr.date;
+	*old_rev_p = old_rev;
 }
 #else
 
-static inline void print_ucode(struct ucode_cpu_info *uci)
+static inline void print_ucode(u32 old_rev, struct ucode_cpu_info *uci)
 {
 	struct microcode_intel *mc;
 
@@ -493,14 +497,14 @@ static inline void print_ucode(struct ucode_cpu_info *uci)
 	if (!mc)
 		return;
 
-	print_ucode_info(uci, mc->hdr.date);
+	print_ucode_info(old_rev, uci, mc->hdr.date);
 }
 #endif
 
 static int apply_microcode_early(struct ucode_cpu_info *uci, bool early)
 {
 	struct microcode_intel *mc;
-	u32 rev;
+	u32 old_rev, rev;
 
 	mc = uci->mc;
 	if (!mc)
@@ -517,6 +521,7 @@ static int apply_microcode_early(struct ucode_cpu_info *uci, bool early)
 		return UCODE_OK;
 	}
 
+	old_rev = rev;
 	/*
 	 * Writeback and invalidate caches before updating microcode to avoid
 	 * internal issues depending on what the microcode is updating.
@@ -533,9 +538,9 @@ static int apply_microcode_early(struct ucode_cpu_info *uci, bool early)
 	uci->cpu_sig.rev = rev;
 
 	if (early)
-		print_ucode(uci);
+		print_ucode(old_rev, uci);
 	else
-		print_ucode_info(uci, mc->hdr.date);
+		print_ucode_info(old_rev, uci, mc->hdr.date);
 
 	return 0;
 }
@@ -739,6 +744,9 @@ static enum ucode_state apply_microcode_intel(int cpu)
 		goto out;
 	}
 
+	if (!prev_rev)
+		prev_rev = rev;
+
 	/*
 	 * Writeback and invalidate caches before updating microcode to avoid
 	 * internal issues depending on what the microcode is updating.
@@ -757,8 +765,8 @@ static enum ucode_state apply_microcode_intel(int cpu)
 	}
 
 	if (bsp && rev != prev_rev) {
-		pr_info("updated to revision 0x%x, date = %04x-%02x-%02x\n",
-			rev,
+		pr_info("update 0x%x -> 0x%x, date = %04x-%02x-%02x\n",
+			prev_rev, rev,
 			mc->hdr.date & 0xffff,
 			mc->hdr.date >> 24,
 			(mc->hdr.date >> 16) & 0xff);
-- 
2.34.1