[PATCH v2 09/19] xen/arm: Introduce a initcall to update cpu_hwcaps by serror_op

[Wei Chen <Wei.Chen@arm.com>]

In the later patches of this series, we want to use the alternative
patching framework to avoid checking serror_op in every entries.
So we define a new cpu feature "SKIP_CHECK_PENDING_VSERROR" for
serror_op. When serror_op is not equal to SERROR_DIVERSE, this
feature will be set to cpu_hwcaps.

Currently, the default serror_op is SERROR_DIVERSE, if we want to
change the serror_op value we have to place the serror parameter
in command line. It seems no problem to update cpu_hwcaps directly
in the serror parameter parsing function.

But one day, if we change the default serror_op to SERROR_PANIC or
SERROR_FORWARD by some security policy. We may not place the serror
parameter in command line. In this case, if we rely on the serror
parameter parsing function to update cpu_hwcaps, this function would
not be invoked and the "SKIP_CHECK_PENDING_VSERROR" could not be
set in cpu_hwcaps.

So, we introduce this initcall to guarantee the cpu_hwcaps can be
updated no matter the serror parameter is placed in the command line
or not.

Signed-off-by: Wei Chen <Wei.Chen@arm.com>
---
v1->v2:
1. Explain this initcall is to future-proof the code in commit
   message.
2. Fix a coding style of this initcall.
---
 xen/arch/arm/traps.c             | 9 +++++++++
 xen/include/asm-arm/cpufeature.h | 3 ++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 955d97c..dafb730 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -120,6 +120,15 @@ static void __init parse_serrors_behavior(const char *str)
 }
 custom_param("serrors", parse_serrors_behavior);
 
+static int __init update_serrors_cpu_caps(void)
+{
+    if ( serrors_op != SERRORS_DIVERSE )
+        cpus_set_cap(SKIP_CHECK_PENDING_VSERROR);
+
+    return 0;
+}
+__initcall(update_serrors_cpu_caps);
+
 void init_traps(void)
 {
     /* Setup Hyp vector base */
diff --git a/xen/include/asm-arm/cpufeature.h b/xen/include/asm-arm/cpufeature.h
index c0a25ae..ec3f9e5 100644
--- a/xen/include/asm-arm/cpufeature.h
+++ b/xen/include/asm-arm/cpufeature.h
@@ -40,8 +40,9 @@
 #define ARM32_WORKAROUND_766422 2
 #define ARM64_WORKAROUND_834220 3
 #define LIVEPATCH_FEATURE   4
+#define SKIP_CHECK_PENDING_VSERROR 5
 
-#define ARM_NCAPS           5
+#define ARM_NCAPS           6
 
 #ifndef __ASSEMBLY__
 
-- 
2.7.4


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