[xen stable-4.12] x86/ucode: Fix error paths in apply_microcode()

[patchbot@xxxxxxx]

commit 94f0bb7c3ff63b7322849cd80ed0d6c2b9998ee4
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Thu Apr 9 09:31:45 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Apr 9 09:31:45 2020 +0200

    x86/ucode: Fix error paths in apply_microcode()
    
    In the unlikley case that patch application completes, but the resutling
    revision isn't expected, sig->rev doesn't get updated to match reality.
    
    It will get adjusted the next time collect_cpu_info() gets called, but in 
the
    meantime Xen might operate on a stale value.  Nothing good will come of 
this.
    
    Rewrite the logic to always update the stashed revision, before worrying 
about
    whether the attempt was a success or failure.
    
    Take the opportunity to make the printk() messages as consistent as 
possible.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Wei Liu <wl@xxxxxxx>
    master commit: d2a0a96cf76603b2e2b87c3ce80c3f9d098327d4
    master date: 2020-03-26 18:57:45 +0000
---
 xen/arch/x86/microcode_amd.c   | 14 +++++++-------
 xen/arch/x86/microcode_intel.c | 21 +++++++++++----------
 2 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/xen/arch/x86/microcode_amd.c b/xen/arch/x86/microcode_amd.c
index 7a854c012f..01bd6d6cc1 100644
--- a/xen/arch/x86/microcode_amd.c
+++ b/xen/arch/x86/microcode_amd.c
@@ -194,7 +194,7 @@ static int apply_microcode(unsigned int cpu)
 {
     unsigned long flags;
     struct ucode_cpu_info *uci = &per_cpu(ucode_cpu_info, cpu);
-    uint32_t rev;
+    uint32_t rev, old_rev = uci->cpu_sig.rev;
     struct microcode_amd *mc_amd = uci->mc.mc_amd;
     struct microcode_header_amd *hdr;
     int hw_err;
@@ -215,6 +215,7 @@ static int apply_microcode(unsigned int cpu)
 
     /* get patch id after patching */
     rdmsrl(MSR_AMD_PATCHLEVEL, rev);
+    uci->cpu_sig.rev = rev;
 
     spin_unlock_irqrestore(&microcode_update_lock, flags);
 
@@ -227,15 +228,14 @@ static int apply_microcode(unsigned int cpu)
     /* check current patch id and patch's id for match */
     if ( hw_err || (rev != hdr->patch_id) )
     {
-        printk(KERN_ERR "microcode: CPU%d update from revision "
-               "%#x to %#x failed\n", cpu, rev, hdr->patch_id);
+        printk(XENLOG_ERR
+               "microcode: CPU%u update rev %#x to %#x failed, result %#x\n",
+               cpu, old_rev, hdr->patch_id, rev);
         return -EIO;
     }
 
-    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;
+    printk(XENLOG_WARNING "microcode: CPU%u updated from revision %#x to 
%#x\n",
+           cpu, old_rev, rev);
 
     return 0;
 }
diff --git a/xen/arch/x86/microcode_intel.c b/xen/arch/x86/microcode_intel.c
index 9657575c29..e511bd853c 100644
--- a/xen/arch/x86/microcode_intel.c
+++ b/xen/arch/x86/microcode_intel.c
@@ -281,9 +281,9 @@ static int apply_microcode(unsigned int cpu)
 {
     unsigned long flags;
     uint64_t msr_content;
-    unsigned int val[2];
     unsigned int cpu_num = raw_smp_processor_id();
     struct ucode_cpu_info *uci = &per_cpu(ucode_cpu_info, cpu_num);
+    uint32_t rev, old_rev = uci->cpu_sig.rev;
 
     /* We should bind the task to the CPU */
     BUG_ON(cpu_num != cpu);
@@ -303,23 +303,24 @@ static int apply_microcode(unsigned int cpu)
 
     /* get the current revision from MSR 0x8B */
     rdmsrl(MSR_IA32_UCODE_REV, msr_content);
-    val[1] = (uint32_t)(msr_content >> 32);
+    uci->cpu_sig.rev = rev = msr_content >> 32;
 
     spin_unlock_irqrestore(&microcode_update_lock, flags);
-    if ( val[1] != uci->mc.mc_intel->hdr.rev )
+
+    if ( rev != uci->mc.mc_intel->hdr.rev )
     {
-        printk(KERN_ERR "microcode: CPU%d update from revision "
-               "%#x to %#x failed. Resulting revision is %#x.\n", cpu_num,
-               uci->cpu_sig.rev, uci->mc.mc_intel->hdr.rev, val[1]);
+        printk(XENLOG_ERR
+               "microcode: CPU%u update rev %#x to %#x failed, result %#x\n",
+               cpu, old_rev, uci->mc.mc_intel->hdr.rev, rev);
         return -EIO;
     }
-    printk(KERN_INFO "microcode: CPU%d updated from revision "
-           "%#x to %#x, date = %04x-%02x-%02x \n",
-           cpu_num, uci->cpu_sig.rev, val[1],
+
+    printk(XENLOG_WARNING
+           "microcode: CPU%u updated from revision %#x to %#x, date = 
%04x-%02x-%02x\n",
+           cpu, old_rev, rev,
            uci->mc.mc_intel->hdr.date & 0xffff,
            uci->mc.mc_intel->hdr.date >> 24,
            (uci->mc.mc_intel->hdr.date >> 16) & 0xff);
-    uci->cpu_sig.rev = val[1];
 
     return 0;
 }
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.12