[PATCH] x86/ucode: Distinguish "ucode already up to date"

[PATCH] x86/ucode: Distinguish "ucode already up to date"

[Andrew Cooper]

Right now, Xen returns -ENOENT for both "the provided blob isn't correct for
this CPU", and "the blob isn't newer than what's loaded".

This in turn causes xen-ucode to exit with an error, when "nothing to do" is
more commonly a success condition.

Handle EEXIST specially and exit cleanly.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Roger Pau Monné <roger.pau@citrix.com>
---
 tools/misc/xen-ucode.c            | 5 ++++-
 xen/arch/x86/cpu/microcode/core.c | 2 +-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/misc/xen-ucode.c b/tools/misc/xen-ucode.c
index c6ae6498d659..390969db3d1c 100644
--- a/tools/misc/xen-ucode.c
+++ b/tools/misc/xen-ucode.c
@@ -125,8 +125,11 @@ int main(int argc, char *argv[])
         exit(1);
     }
 
+    errno = 0;
     ret = xc_microcode_update(xch, buf, len);
-    if ( ret )
+    if ( ret == -1 && errno == EEXIST )
+        printf("Microcode already up to date\n");
+    else if ( ret )
     {
         fprintf(stderr, "Failed to update microcode. (err: %s)\n",
                 strerror(errno));
diff --git a/xen/arch/x86/cpu/microcode/core.c b/xen/arch/x86/cpu/microcode/core.c
index e738a88f5cd1..762111838f5f 100644
--- a/xen/arch/x86/cpu/microcode/core.c
+++ b/xen/arch/x86/cpu/microcode/core.c
@@ -640,7 +640,7 @@ static long cf_check microcode_update_helper(void *data)
                    "microcode: couldn't find any newer%s revision in the provided blob!\n",
                    opt_ucode_allow_same ? " (or the same)" : "");
             microcode_free_patch(patch);
-            ret = -ENOENT;
+            ret = -EEXIST;
 
             goto put;
         }

base-commit: a2330b51df267e20e66bbba6c5bf08f0570ed58b
-- 
2.30.2

Re: [PATCH] x86/ucode: Distinguish "ucode already up to date"

[Roger Pau Monné]

On Wed, May 08, 2024 at 05:18:42PM +0100, Andrew Cooper wrote:
> Right now, Xen returns -ENOENT for both "the provided blob isn't correct for
> this CPU", and "the blob isn't newer than what's loaded".
> 
> This in turn causes xen-ucode to exit with an error, when "nothing to do" is
> more commonly a success condition.
> 
> Handle EEXIST specially and exit cleanly.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Acked-by: Roger Pau Monné <roger.pau@citrix.com>

Thanks.