From: Jan Beulich <jbeulich@suse.com>
Date: Fri, 14 Oct 2016 12:09:42 +0000 (+0200)
Subject: x86/Viridian: don't depend on undefined register state
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~181
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=a709a3a646302e95ba42beac89264f6cdacd0c64;p=xen.git

x86/Viridian: don't depend on undefined register state

The high halves of all GPRs are undefined in 32-bit and compat modes,
and the dependency is being obfuscated by our structure field names not
matching architectural register names (it was actually while putting
together a patch to correct this when I noticed the issue here).

For consistency also use the architecturally correct names on the
output side.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
---

diff --git a/xen/arch/x86/hvm/viridian.c b/xen/arch/x86/hvm/viridian.c
index 1734b7ed91..f6abdd2807 100644
--- a/xen/arch/x86/hvm/viridian.c
+++ b/xen/arch/x86/hvm/viridian.c
@@ -667,9 +667,9 @@ int viridian_hypercall(struct cpu_user_regs *regs)
         output_params_gpa = regs->r8;
         break;
     case 4:
-        input.raw = ((uint64_t)regs->edx << 32) | regs->eax;
-        input_params_gpa = ((uint64_t)regs->ebx << 32) | regs->ecx;
-        output_params_gpa = ((uint64_t)regs->edi << 32) | regs->esi;
+        input.raw = (regs->rdx << 32) | regs->_eax;
+        input_params_gpa = (regs->rbx << 32) | regs->_ecx;
+        output_params_gpa = (regs->rdi << 32) | regs->_esi;
         break;
     default:
         goto out;
@@ -770,8 +770,8 @@ out:
         regs->rax = output.raw;
         break;
     default:
-        regs->edx = output.raw >> 32;
-        regs->eax = output.raw;
+        regs->rdx = output.raw >> 32;
+        regs->rax = (uint32_t)output.raw;
         break;
     }