[PATCH v3 01/13] viridian: don't blindly write to 32-bit registers is 'mode' is invalid

[Paul Durrant <paul@xxxxxxx>]

From: Paul Durrant <pdurrant@xxxxxxxxxx>

If hvm_guest_x86_mode() returns something other than 8 or 4 then
viridian_hypercall() will return immediately but, on the way out, will write
back status as if 'mode' was 4. This patch simply makes it leave the registers
alone.

NOTE: The formatting of the 'out' label and the switch statement are also
      adjusted as per CODING_STYLE.

Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
---
Cc: Wei Liu <wl@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>

v2:
 - New in v2
---
 xen/arch/x86/hvm/viridian/viridian.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/viridian/viridian.c 
b/xen/arch/x86/hvm/viridian/viridian.c
index dc7183a54627..54035f75cb1a 100644
--- a/xen/arch/x86/hvm/viridian/viridian.c
+++ b/xen/arch/x86/hvm/viridian/viridian.c
@@ -692,13 +692,14 @@ int viridian_hypercall(struct cpu_user_regs *regs)
         break;
     }
 
-out:
+ out:
     output.result = status;
     switch (mode) {
     case 8:
         regs->rax = output.raw;
         break;
-    default:
+
+    case 4:
         regs->rdx = output.raw >> 32;
         regs->rax = (uint32_t)output.raw;
         break;
-- 
2.20.1