x86/paravirt: add debugging for missing operations

Rather than just jumping to 0 when there's a missing operation, raise a BUG.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9441e46cb49b7a34e0a6a35bbb3756a01710eb89..67e5275f03c851e790da5512f4b83a3889a0fcbc 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -435,6 +435,13 @@ config PARAVIRT_CLOCK
 
 endif
 
+config PARAVIRT_DEBUG
+       bool "paravirt-ops debugging"
+       depends on PARAVIRT && DEBUG_KERNEL
+       help
+         Enable to debug paravirt_ops internals.  Specifically, BUG if
+        a paravirt_op is missing when it is called.
+
 config MEMTEST
        bool "Memtest"
        depends on X86_64

diff --git a/include/asm-x86/paravirt.h b/include/asm-x86/paravirt.h
index 5467e2cff4bca8c4cac68d4580d52e400d2e8417..198293bed46f0cb541b4daf272aba2930a5b34c4 100644 (file)
--- a/include/asm-x86/paravirt.h
+++ b/include/asm-x86/paravirt.h
@@ -459,10 +459,17 @@ int paravirt_disable_iospace(void);
 #define VEXTRA_CLOBBERS         , "rax", "r8", "r9", "r10", "r11"
 #endif
 
+#ifdef CONFIG_PARAVIRT_DEBUG
+#define PVOP_TEST_NULL(op)     BUG_ON(op == NULL)
+#else
+#define PVOP_TEST_NULL(op)     ((void)op)
+#endif
+
 #define __PVOP_CALL(rettype, op, pre, post, ...)                       \
        ({                                                              \
                rettype __ret;                                          \
                PVOP_CALL_ARGS;                                 \
+               PVOP_TEST_NULL(op);                                     \
                /* This is 32-bit specific, but is okay in 64-bit */    \
                /* since this condition will never hold */              \
                if (sizeof(rettype) > sizeof(unsigned long)) {          \
@@ -491,6 +498,7 @@ int paravirt_disable_iospace(void);
 #define __PVOP_VCALL(op, pre, post, ...)                               \
        ({                                                              \
                PVOP_VCALL_ARGS;                                        \
+               PVOP_TEST_NULL(op);                                     \
                asm volatile(pre                                        \
                             paravirt_alt(PARAVIRT_CALL)                \
                             post                                       \