[Xen-devel] [PATCH] x86/Viridian: don't depend on undefined register state

["Jan Beulich" <JBeulich@xxxxxxxx>]

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@xxxxxxxx>

--- a/xen/arch/x86/hvm/viridian.c
+++ b/xen/arch/x86/hvm/viridian.c
@@ -667,9 +667,9 @@ int viridian_hypercall(struct cpu_user_r
         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;
     }

Attachment: x86-Viridian-regs.patch
Description: Text document

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