[PATCH] KVM: X86: Avoid explictly fetch instruction in x86_decode_insn()

From: Peter Xu
Date: Tue Mar 03 2020 - 21:17:05 EST


insn_fetch() will always implicitly refill instruction buffer properly
when the buffer is empty, so we don't need to explicitly fetch it even
if insn_len==0 for x86_decode_insn().

Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
arch/x86/kvm/emulate.c | 5 -----
1 file changed, 5 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index dd19fb3539e0..04f33c1ca926 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -5175,11 +5175,6 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
ctxt->opcode_len = 1;
if (insn_len > 0)
memcpy(ctxt->fetch.data, insn, insn_len);
- else {
- rc = __do_insn_fetch_bytes(ctxt, 1);
- if (rc != X86EMUL_CONTINUE)
- goto done;
- }

switch (mode) {
case X86EMUL_MODE_REAL:
--
2.24.1