[RFC v1 2/7] x86/hvm: Introduce hvm_emulate_one_ctxt

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

This is like hvm_emulate_one_insn() but takes an existing
hvm_emulate_ctxt as a parameter. This will be needed to merge the
instruction emulator and VMEXIT fast paths.

Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
---
 xen/arch/x86/hvm/io.c                  | 17 +++++++++++------
 xen/arch/x86/include/asm/hvm/emulate.h |  1 +
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
index d9838c36d330..7dc6f64b646e 100644
--- a/xen/arch/x86/hvm/io.c
+++ b/xen/arch/x86/hvm/io.c
@@ -53,27 +53,32 @@ void send_timeoffset_req(unsigned long timeoff)
 bool hvm_emulate_one_insn(hvm_emulate_validate_t *validate, const char *descr)
 {
     struct hvm_emulate_ctxt ctxt;
-    int rc;
 
     hvm_emulate_init_once(&ctxt, validate, descr, guest_cpu_user_regs());
+    return hvm_emulate_one_ctxt(&ctxt);
+}
 
-    switch ( rc = hvm_emulate_one(&ctxt, VIO_no_completion) )
+bool hvm_emulate_one_ctxt(struct hvm_emulate_ctxt *ctxt)
+{
+    int rc = hvm_emulate_one(ctxt, VIO_no_completion);
+
+    switch ( rc )
     {
     case X86EMUL_UNHANDLEABLE:
-        hvm_dump_emulation_state(XENLOG_G_WARNING, ctxt.descr, &ctxt, rc);
+        hvm_dump_emulation_state(XENLOG_G_WARNING, ctxt->descr, ctxt, rc);
         return false;
 
     case X86EMUL_UNRECOGNIZED:
-        hvm_dump_emulation_state(XENLOG_G_WARNING, ctxt.descr, &ctxt, rc);
+        hvm_dump_emulation_state(XENLOG_G_WARNING, ctxt->descr, ctxt, rc);
         hvm_inject_hw_exception(X86_EXC_UD, X86_EVENT_NO_EC);
         break;
 
     case X86EMUL_EXCEPTION:
-        hvm_inject_event(&ctxt.ctxt.event);
+        hvm_inject_event(&ctxt->ctxt.event);
         break;
     }
 
-    hvm_emulate_writeback(&ctxt);
+    hvm_emulate_writeback(ctxt);
 
     return true;
 }
diff --git a/xen/arch/x86/include/asm/hvm/emulate.h 
b/xen/arch/x86/include/asm/hvm/emulate.h
index 2801d14d5455..084e2bd90588 100644
--- a/xen/arch/x86/include/asm/hvm/emulate.h
+++ b/xen/arch/x86/include/asm/hvm/emulate.h
@@ -65,6 +65,7 @@ enum emul_kind {
 bool __nonnull(1, 2) hvm_emulate_one_insn(
     hvm_emulate_validate_t *validate,
     const char *descr);
+bool hvm_emulate_one_ctxt(struct hvm_emulate_ctxt *ctxt);
 int hvm_emulate_one(
     struct hvm_emulate_ctxt *hvmemul_ctxt,
     enum vio_completion completion);
-- 
2.53.0