xen/23993-x86-microcode-amd-fix-23871.patch

References: bnc#725169

# HG changeset patch
# User Jan Beulich <jbeulich@novell.com>
# Date 1319475620 -3600
# Node ID e458dfc35b8d3be04a9b72c30ff97163e27a7314
# Parent  ffe861c1d5dfa8f4485052e5600e06124105033f
x86/ucode-amd: fix regression from c/s 23871:503ee256fecf

microcode_fits() must return distinct values for the success and
no-fit-but-no-error cases, so the caller can react accordingly. Make
it return 1 in the success case, and adjust its single caller.

Also remove an impossible code path - install_equiv_cpu_table(), which
gets called prior to microcode_fits(), never leaves equiv_cpu_table
being NULL without also returning an error.

Note that this is still awaiting testing on a system where the
regression was actually observed (which also requires a new enough
microcode_ctl package). Note also that this will need to be
backported to 4.0 and 4.1 (or the broken c/s that got backported
there reverted).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Committed-by: Keir Fraser <keir@xen.org>

Index: xen-4.1.3-testing/xen/arch/x86/microcode_amd.c
===================================================================
--- xen-4.1.3-testing.orig/xen/arch/x86/microcode_amd.c
+++ xen-4.1.3-testing/xen/arch/x86/microcode_amd.c
@@ -76,14 +76,6 @@ static int microcode_fits(const struct m
     /* We should bind the task to the CPU */
     BUG_ON(cpu != raw_smp_processor_id());
 
-    if ( equiv_cpu_table == NULL )
-    {
-        printk(KERN_INFO "microcode: CPU%d microcode update with "
-               "version 0x%x (current=0x%x)\n",
-               cpu, mc_header->patch_id, uci->cpu_sig.rev);
-        goto out;
-    }
-
     current_cpu_id = cpuid_eax(0x00000001);
 
     for ( i = 0; equiv_cpu_table[i].installed_cpu != 0; i++ )
@@ -117,7 +109,6 @@ static int microcode_fits(const struct m
            "update with version 0x%x (current=0x%x)\n",
            cpu, mc_header->patch_id, uci->cpu_sig.rev);
 
-out:
     return 1;
 }