In commit 6f059e634dcd("x86/microcode: Clarify the late load logic"), the
return value is UCODE_OK if the load is up-to-date in amd platform, which
leads to load_late_locked() returning -EBADFD.

Add UCODE_OK in switch case to avoid this error.

Fixes: 6f059e634dcd ("x86/microcode: Clarify the late load logic")
Signed-off-by: Annie Li <jiayanli@google.com>
---
Changelog since v1:
- Change the return value back to UCODE_OK and adding a switch case
  about UCODE_OK.

 arch/x86/kernel/cpu/microcode/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index b3658d11e7b69..2309321cf6a19 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -686,6 +686,8 @@ static int load_late_locked(void)
 		return load_late_stop_cpus(true);
 	case UCODE_NFOUND:
 		return -ENOENT;
+	case UCODE_OK:
+		return 0;
 	default:
 		return -EBADFD;
 	}
-- 
2.49.0.901.g37484f566f-goog

The following commit has been merged into the x86/microcode branch of tip:

Commit-ID:     b43dc4ab097859c24e2a6993119c927cffc856aa
Gitweb:        https://git.kernel.org/tip/b43dc4ab097859c24e2a6993119c927cffc856aa
Author:        Annie Li <jiayanli@google.com>
AuthorDate:    Wed, 30 Apr 2025 05:34:24 
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Wed, 30 Apr 2025 17:10:46 +02:00

x86/microcode/AMD: Do not return error when microcode update is not necessary

After

  6f059e634dcd("x86/microcode: Clarify the late load logic"),

if the load is up-to-date, the AMD side returns UCODE_OK which leads to
load_late_locked() returning -EBADFD.

Handle UCODE_OK in the switch case to avoid this error.

  [ bp: Massage commit message. ]

Fixes: 6f059e634dcd ("x86/microcode: Clarify the late load logic")
Signed-off-by: Annie Li <jiayanli@google.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250430053424.77438-1-jiayanli@google.com
---
 arch/x86/kernel/cpu/microcode/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index b3658d1..2309321 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -686,6 +686,8 @@ static int load_late_locked(void)
 		return load_late_stop_cpus(true);
 	case UCODE_NFOUND:
 		return -ENOENT;
+	case UCODE_OK:
+		return 0;
 	default:
 		return -EBADFD;
 	}