[Xen-devel] [PATCH 2/2] x86/emul: Pass shadow register state to the vmfunc() hook

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

vmfunc can in principle modify register state, so should operate on the shadow
register state rather than the starting state of emulation.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
 xen/arch/x86/hvm/emulate.c             | 3 ++-
 xen/arch/x86/x86_emulate/x86_emulate.c | 2 +-
 xen/arch/x86/x86_emulate/x86_emulate.h | 1 +
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index aa1b716..fae666a 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -1646,13 +1646,14 @@ static int hvmemul_invlpg(
 }
 
 static int hvmemul_vmfunc(
+    struct cpu_user_regs *regs,
     struct x86_emulate_ctxt *ctxt)
 {
     int rc;
 
     if ( !hvm_funcs.altp2m_vcpu_emulate_vmfunc )
         return X86EMUL_UNHANDLEABLE;
-    rc = hvm_funcs.altp2m_vcpu_emulate_vmfunc(ctxt->regs);
+    rc = hvm_funcs.altp2m_vcpu_emulate_vmfunc(regs);
     if ( rc == X86EMUL_EXCEPTION )
         x86_emul_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC, ctxt);
 
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 3076c0c..c9ffc56 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -4463,7 +4463,7 @@ x86_emulate(
             generate_exception_if(lock_prefix | rep_prefix() | (vex.pfx == 
vex_66),
                                   EXC_UD);
             fail_if(!ops->vmfunc);
-            if ( (rc = ops->vmfunc(ctxt)) != X86EMUL_OKAY )
+            if ( (rc = ops->vmfunc(&_regs, ctxt)) != X86EMUL_OKAY )
                 goto done;
             goto no_writeback;
 
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.h 
b/xen/arch/x86/x86_emulate/x86_emulate.h
index 75f57ba..d70b534 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.h
+++ b/xen/arch/x86/x86_emulate/x86_emulate.h
@@ -448,6 +448,7 @@ struct x86_emulate_ops
 
     /* vmfunc: Emulate VMFUNC via given set of EAX ECX inputs */
     int (*vmfunc)(
+        struct cpu_user_regs *regs,
         struct x86_emulate_ctxt *ctxt);
 };
 
-- 
1.9.1


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