[Xen-changelog] [xen stable-4.2] x86/MCE: disable if MCE banks are not present

[patchbot@xxxxxxx]

commit 83525ae2fae22f6684b4eb204c40d5b96c12dde9
Author:     Aravindh Puthiyaparambil <aravindp@xxxxxxxxx>
AuthorDate: Thu Jun 13 11:19:20 2013 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Jun 13 11:19:20 2013 +0200

    x86/MCE: disable if MCE banks are not present
    
    When booting Xen on VMware ESX 5.1 and Workstation 9, you hit a GPF
    during MCE initialization. The culprit is line 631 in
    set_poll_bankmask():
                    bitmap_copy(mb->bank_map, mca_allbanks->bank_map, 
nr_mce_banks);
    
    What is happening is that in mca_cap_init(), nr_mce_banks is being set
    to 0. This causes the allocation of bank_map to be set to
    ZERO_BLOCK_PTR which is the return value for zero-size allocation by
    xzalloc_array()/_xmalloc(). This results in the bitmap_copy() to fail
    disastrously. The following patch fixes this issue.
    
    Signed-off-by: Aravindh Puthiyaparambil <aravindp@xxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Christoph Egger <chegger@xxxxxxxxx>
    master commit: 5cffb77c4072fa5b46700a2dbb3e46c5a54eba6d
    master date: 2013-06-03 15:42:46 +0200
---
 xen/arch/x86/cpu/mcheck/mce.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
index 50596e3..d03769c 100644
--- a/xen/arch/x86/cpu/mcheck/mce.c
+++ b/xen/arch/x86/cpu/mcheck/mce.c
@@ -739,7 +739,14 @@ int mca_cap_init(void)
     }
     nr_mce_banks = msr_content & MCG_CAP_COUNT;
 
-    /* mcabanks_alloc depends on nr_mcebanks */
+    if (!nr_mce_banks)
+    {
+        printk(XENLOG_INFO "CPU%u: No MCE banks present. "
+               "Machine check support disabled\n", smp_processor_id());
+        return -ENODEV;
+    }
+
+    /* mcabanks_alloc depends on nr_mce_banks */
     if (!mca_allbanks)
     {
         int i;
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.2

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