linux-kernel - Re: [PATCH 2/2] x86/microcode: Rework early revisions reporting

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Message-ID: <20231202163850.GCZWtdmrMoJqyAiycZ@fat_crate.local>
Date:   Sat, 2 Dec 2023 17:38:50 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Ashok Raj <ashok.raj@...el.com>
Cc:     X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 2/2] x86/microcode: Rework early revisions reporting

On Fri, Dec 01, 2023 at 01:32:37PM -0800, Ashok Raj wrote:
> dmesg for the microcode part here below:
> 
> https://paste.debian.net/hidden/e911dffc/

Thanks, it is all clear now.

This should fix it:

---
From: "Borislav Petkov (AMD)" <bp@...en8.de>
Date: Fri, 1 Dec 2023 14:35:06 +0100
Subject: [PATCH] x86/microcode/intel: Set new revision only after a successful update

This was meant to be done only when early microcode got updated
successfully. Move it into the if-branch.

Also, make sure the current revision is read unconditionally and only
once.

Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
---
 arch/x86/kernel/cpu/microcode/intel.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 070426b9895f..334972c097d9 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -370,14 +370,14 @@ static __init struct microcode_intel *get_microcode_blob(struct ucode_cpu_info *
 {
 	struct cpio_data cp;
 
+	intel_collect_cpu_info(&uci->cpu_sig);
+
 	if (!load_builtin_intel_microcode(&cp))
 		cp = find_microcode_in_initrd(ucode_path);
 
 	if (!(cp.data && cp.size))
 		return NULL;
 
-	intel_collect_cpu_info(&uci->cpu_sig);
-
 	return scan_microcode(cp.data, cp.size, uci, save);
 }
 
@@ -410,13 +410,13 @@ void __init load_ucode_intel_bsp(struct early_load_data *ed)
 {
 	struct ucode_cpu_info uci;
 
-	ed->old_rev = intel_get_microcode_revision();
-
 	uci.mc = get_microcode_blob(&uci, false);
-	if (uci.mc && apply_microcode_early(&uci) == UCODE_UPDATED)
-		ucode_patch_va = UCODE_BSP_LOADED;
+	ed->old_rev = uci.cpu_sig.rev;
 
-	ed->new_rev = uci.cpu_sig.rev;
+	if (uci.mc && apply_microcode_early(&uci) == UCODE_UPDATED) {
+		ucode_patch_va = UCODE_BSP_LOADED;
+		ed->new_rev = uci.cpu_sig.rev;
+	}
 }
 
 void load_ucode_intel_ap(void)
-- 
2.42.0.rc0.25.ga82fb66fed25

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette