[PATCH v12 3/3] xen/riscv: refactor decode_trap_cause()

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

Use array_access_nospec() to prevent guest speculation.

Avoid double access of trap_causes[cause].

Suggested-by: Jan Beulich <jbeulich@xxxxxxxx>
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
Changes in V12:
 - New patch.
---
 xen/arch/riscv/traps.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/xen/arch/riscv/traps.c b/xen/arch/riscv/traps.c
index 72ffdcd79e..51f6e45ccc 100644
--- a/xen/arch/riscv/traps.c
+++ b/xen/arch/riscv/traps.c
@@ -7,6 +7,7 @@
 
 #include <xen/bug.h>
 #include <xen/lib.h>
+#include <xen/nospec.h>
 #include <xen/sched.h>
 
 #include <asm/processor.h>
@@ -48,9 +49,10 @@ static const char *decode_trap_cause(unsigned long cause)
         [CAUSE_STORE_GUEST_PAGE_FAULT] = "Guest Store/AMO Page Fault",
     };
 
-    if ( cause < ARRAY_SIZE(trap_causes) && trap_causes[cause] )
-        return trap_causes[cause];
-    return "UNKNOWN";
+    const char *res = cause < ARRAY_SIZE(trap_causes) ? 
array_access_nospec(trap_causes, cause)
+                                                      : NULL;
+
+    return res ?: "UNKNOWN";
 }
 
 static const char *decode_reserved_interrupt_cause(unsigned long irq_cause)
-- 
2.45.2