Re: [PATCH 7 of 7] KEXEC: correctly revert x2apic state when kexecing [Reformatted, v2]

[Andrew Cooper <andrew.cooper3@citrix.com>]

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On 15/06/11 16:50, Ian Campbell wrote:
> On Wed, 2011-06-15 at 16:41 +0100, Andrew Cooper wrote:
>> Tweaked the patch to prevent IOMMU_WAIT_OP panicking on the kexec path. 
>> Unfortunately, this has to rely on the kexecing variable.
>>
>> As with the other hacks in this patch, I cant see a better way of
>> solving the problem.
>>
>
>> @@ -99,8 +100,9 @@ do {                                    
>>          if ( cond )                                 \
>>              break;                                  \
>>          if ( NOW() > start_time + DMAR_OPERATION_TIMEOUT )      \
>> -            panic("%s:%d:%s: DMAR hardware is malfunctional\n", \
>> -                  __FILE__, __LINE__, __func__);                \
>> +            if ( !kexecing )                                    \
>> +                panic("%s:%d:%s: DMAR hardware is malfunctional\n",\
>> +                      __FILE__, __LINE__, __func__);            \
>>          cpu_relax();                                            \
>>      }                                                           \
>>  } while (0)
> I think you want an "else break" here to cause it to struggle onwards
> rather than the infinite loop you get otherwise.
>
> Ian
Yep - Fixed and reformatted against staging again.

-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com


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KEXEC: prevent panic on the kexec path when talking to the DMAR hardware

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

diff -r 23c068b10923 xen/drivers/passthrough/vtd/dmar.h
--- a/xen/drivers/passthrough/vtd/dmar.h	Wed Jun 15 16:16:41 2011 +0100
+++ b/xen/drivers/passthrough/vtd/dmar.h	Wed Jun 15 16:57:39 2011 +0100
@@ -23,6 +23,7 @@
 
 #include <xen/list.h>
 #include <xen/iommu.h>
+#include <xen/kexec.h>
 
 /* This one is for interrupt remapping */
 struct acpi_ioapic_unit {
@@ -98,9 +99,13 @@ do {                                    
         sts = op(iommu->reg, offset);               \
         if ( cond )                                 \
             break;                                  \
-        if ( NOW() > start_time + DMAR_OPERATION_TIMEOUT )      \
-            panic("%s:%d:%s: DMAR hardware is malfunctional\n", \
-                  __FILE__, __LINE__, __func__);                \
+        if ( NOW() > start_time + DMAR_OPERATION_TIMEOUT ) {    \
+            if ( !kexecing )                                    \
+                panic("%s:%d:%s: DMAR hardware is malfunctional\n",\
+                      __FILE__, __LINE__, __func__);            \
+            else                                                \
+                break;                                          \
+        }                                                       \
         cpu_relax();                                            \
     }                                                           \
 } while (0)

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