From: Julien Grall <julien.grall@arm.com>
Date: Wed, 27 Jul 2016 16:37:06 +0000 (+0100)
Subject: xen/arm: cpufeature: Provide an helper to check if a capability is supported
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~631
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=64eb606000f1258267f27e6819c59848e2226773;p=xen.git

xen/arm: cpufeature: Provide an helper to check if a capability is supported

The CPU capabilities will be set depending on the value found in the CPU
registers. This patch provides a generic to go through a set of capabilities
and find which one should be enabled.

The parameter "info" is used to display the kind of capability updated (e.g
workaround, feature...).

Signed-off-by: Julien Grall <julien.grall@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---

diff --git a/xen/arch/arm/cpufeature.c b/xen/arch/arm/cpufeature.c
index 7a1b56b67e..088625bbac 100644
--- a/xen/arch/arm/cpufeature.c
+++ b/xen/arch/arm/cpufeature.c
@@ -24,6 +24,22 @@
 
 DECLARE_BITMAP(cpu_hwcaps, ARM_NCAPS);
 
+void update_cpu_capabilities(const struct arm_cpu_capabilities *caps,
+                             const char *info)
+{
+    int i;
+
+    for ( i = 0; caps[i].matches; i++ )
+    {
+        if ( !caps[i].matches(&caps[i]) )
+            continue;
+
+        if ( !cpus_have_cap(caps[i].capability) && caps[i].desc )
+            printk(XENLOG_INFO "%s: %s\n", info, caps[i].desc);
+        cpus_set_cap(caps[i].capability);
+    }
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/asm-arm/cpufeature.h b/xen/include/asm-arm/cpufeature.h
index 2bebad16cd..be2414c671 100644
--- a/xen/include/asm-arm/cpufeature.h
+++ b/xen/include/asm-arm/cpufeature.h
@@ -62,6 +62,15 @@ static inline void cpus_set_cap(unsigned int num)
         __set_bit(num, cpu_hwcaps);
 }
 
+struct arm_cpu_capabilities {
+    const char *desc;
+    u16 capability;
+    bool_t (*matches)(const struct arm_cpu_capabilities *);
+};
+
+void update_cpu_capabilities(const struct arm_cpu_capabilities *caps,
+                             const char *info);
+
 #endif /* __ASSEMBLY__ */
 
 #endif