Hi all:
I have the following patch to SIDT emulation instruction, but it
does not work because we can not writeback more then 8 bytes
memory, the SIDT under PROTO64 is 10 bytes.
I change the code to write twice, first time write limit, then write
address, and it does not work too. If I change the c->dst.bytes
to only writeback 8 bytes, it will writeback 8 bytes.
Is this a bug of KVM or it is the IO limit?
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index dc3a648..43a6819 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2213,7 +2213,8 @@ static struct opcode group5[] = {
};
static struct group_dual group7 = { {
- N, N, D(ModRM | SrcMem | Priv), D(ModRM | SrcMem | Priv),
+ N, D(DstMem | SrcNone | ModRM | Op3264),
+ D(ModRM | SrcMem | Priv), D(ModRM | SrcMem | Priv),
D(SrcNone | ModRM | DstMem | Mov), N,
D(SrcMem16 | ModRM | Mov | Priv),
D(SrcMem | ModRM | ByteOp | Priv | NoAccess),
@@ -3282,6 +3283,7 @@ twobyte_insn:
switch (c->modrm_reg) {
u16 size;
unsigned long address;
+ struct desc_ptr dt;
case 0: /* vmcall */
if (c->modrm_mod != 3 || c->modrm_rm != 1)
@@ -3296,6 +3298,11 @@ twobyte_insn:
/* Disable writeback. */
c->dst.type = OP_NONE;
break;
+ case 1: /* sidt */
+ ops->get_idt(&dt, ctxt->vcpu);
+ c->dst.bytes = c->op_bytes + 2;
+ memcpy(&c->dst.valptr, &dt, c->dst.bytes);
+ break;
case 2: /* lgdt */
rc = read_descriptor(ctxt, ops, c->src.addr.mem,
&size, &address, c->op_bytes);
--
1.7.0.4
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