[Xen-devel] [PATCH] x86/ucode: Improve error handling and container file processing on AMD

[Boris Ostrovsky <boris.ostrovsky@xxxxxxx>]

Do not report error when a patch is not appplicable to current processor,
simply skip it and move on to next patch in container file.

Process container file to the end instead of stopping at the first
applicable patch.

Log the fact that a patch has been applied at KERN_WARNING level, add
CPU number to debug messages.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxx>
---
 xen/arch/x86/microcode_amd.c |   69 +++++++++++++++++++++++-------------------
 1 file changed, 38 insertions(+), 31 deletions(-)

diff --git a/xen/arch/x86/microcode_amd.c b/xen/arch/x86/microcode_amd.c
index 7a54001..bb5968e 100644
--- a/xen/arch/x86/microcode_amd.c
+++ b/xen/arch/x86/microcode_amd.c
@@ -88,13 +88,13 @@ static int collect_cpu_info(int cpu, struct cpu_signature 
*csig)
 
     rdmsrl(MSR_AMD_PATCHLEVEL, csig->rev);
 
-    printk(KERN_DEBUG "microcode: collect_cpu_info: patch_id=%#x\n",
-           csig->rev);
+    printk(KERN_DEBUG "microcode: CPU%d collect_cpu_info: patch_id=%#x\n",
+           cpu, csig->rev);
 
     return 0;
 }
 
-static int microcode_fits(const struct microcode_amd *mc_amd, int cpu)
+static bool_t microcode_fits(const struct microcode_amd *mc_amd, int cpu)
 {
     struct ucode_cpu_info *uci = &per_cpu(ucode_cpu_info, cpu);
     const struct microcode_header_amd *mc_header = mc_amd->mpb;
@@ -125,11 +125,16 @@ static int microcode_fits(const struct microcode_amd 
*mc_amd, int cpu)
         printk(KERN_DEBUG "microcode: CPU%d patch does not match "
                "(patch is %x, cpu base id is %x) \n",
                cpu, mc_header->processor_rev_id, equiv_cpu_id);
-        return -EINVAL;
+        return 0;
     }
 
     if ( mc_header->patch_id <= uci->cpu_sig.rev )
+    {
+        printk(KERN_DEBUG "microcode: CPU%d patching is not needed: "
+               "patch provides level 0x%x, cpu is at 0x%x \n",
+               cpu, mc_header->patch_id, uci->cpu_sig.rev);
         return 0;
+    }
 
     printk(KERN_DEBUG "microcode: CPU%d found a matching microcode "
            "update with version %#x (current=%#x)\n",
@@ -173,7 +178,7 @@ static int apply_microcode(int cpu)
         return -EIO;
     }
 
-    printk(KERN_INFO "microcode: CPU%d updated from revision %#x to %#x\n",
+    printk(KERN_WARNING "microcode: CPU%d updated from revision %#x to %#x\n",
            cpu, uci->cpu_sig.rev, hdr->patch_id);
 
     uci->cpu_sig.rev = rev;
@@ -181,7 +186,7 @@ static int apply_microcode(int cpu)
     return 0;
 }
 
-static int get_next_ucode_from_buffer_amd(
+static int get_ucode_from_buffer_amd(
     struct microcode_amd *mc_amd,
     const void *buf,
     size_t bufsize,
@@ -194,8 +199,12 @@ static int get_next_ucode_from_buffer_amd(
     off = *offset;
 
     /* No more data */
-    if ( off >= bufsize )
-        return 1;
+    if ( off >= bufsize ) 
+    {
+        printk(KERN_ERR "microcode: error! "
+               "ucode buffer overrun\n");
+        return -EINVAL;
+    }
 
     mpbuf = (const struct mpbhdr *)&bufp[off];
     if ( mpbuf->type != UCODE_UCODE_TYPE )
@@ -205,8 +214,8 @@ static int get_next_ucode_from_buffer_amd(
         return -EINVAL;
     }
 
-    printk(KERN_DEBUG "microcode: size %zu, block size %u, offset %zu\n",
-           bufsize, mpbuf->len, off);
+    printk(KERN_DEBUG "microcode: CPU%d size %zu, block size %u, offset %zu\n",
+           raw_smp_processor_id(), bufsize, mpbuf->len, off);
 
     if ( (off + mpbuf->len) > bufsize )
     {
@@ -278,8 +287,8 @@ static int cpu_request_microcode(int cpu, const void *buf, 
size_t bufsize)
 {
     struct microcode_amd *mc_amd, *mc_old;
     size_t offset = bufsize;
+    size_t last_offset, applied_offset = 0;
     int error = 0;
-    int ret;
     struct ucode_cpu_info *uci = &per_cpu(ucode_cpu_info, cpu);
 
     /* We should bind the task to the CPU */
@@ -321,33 +330,32 @@ static int cpu_request_microcode(int cpu, const void 
*buf, size_t bufsize)
      */
     mc_amd->mpb = NULL;
     mc_amd->mpb_size = 0;
-    while ( (ret = get_next_ucode_from_buffer_amd(mc_amd, buf, bufsize,
-                                                  &offset)) == 0 )
+    last_offset = offset;
+    while ( (error = get_ucode_from_buffer_amd(mc_amd, buf, bufsize,
+                                               &offset)) == 0 )
     {
-        error = microcode_fits(mc_amd, cpu);
-        if (error <= 0)
-            continue;
+        if ( microcode_fits(mc_amd, cpu) )
+            if ( apply_microcode(cpu) == 0 )
+                applied_offset = last_offset;
 
-        error = apply_microcode(cpu);
-        if (error == 0)
-        {
-            error = 1;
+        last_offset = offset;
+
+        if ( offset >= bufsize )
             break;
-        }
     }
 
-    if ( ret < 0 )
-        error = ret;
-
     /* On success keep the microcode patch for
      * re-apply on resume.
      */
-    if ( error == 1 )
+    if ( applied_offset != 0 )
     {
-        xfree(mc_old);
-        error = 0;
+        error = get_ucode_from_buffer_amd(mc_amd, buf, bufsize,
+                                          &applied_offset);
+        if (error == 0)
+            xfree(mc_old);
     }
-    else
+
+    if ( applied_offset == 0 || error != 0 )
     {
         xfree(mc_amd);
         uci->mc.mc_amd = mc_old;
@@ -364,10 +372,9 @@ static int microcode_resume_match(int cpu, const void *mc)
     struct ucode_cpu_info *uci = &per_cpu(ucode_cpu_info, cpu);
     struct microcode_amd *mc_amd = uci->mc.mc_amd;
     const struct microcode_amd *src = mc;
-    int res = microcode_fits(src, cpu);
 
-    if ( res <= 0 )
-        return res;
+    if ( microcode_fits(src, cpu) == 0 )
+        return 0;
 
     if ( src != mc_amd )
     {
-- 
1.7.10.4



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