KVM: x86 emulator: MMX support
General support for the MMX instruction set. Special care is taken
to trap pending x87 exceptions so that they are properly reflected
to the guest.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index fb39e0b..0011b4a 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -142,6 +142,7 @@
#define Src2FS (OpFS << Src2Shift)
#define Src2GS (OpGS << Src2Shift)
#define Src2Mask (OpMask << Src2Shift)
+#define Mmx ((u64)1 << 40) /* MMX Vector instruction */
#define Aligned ((u64)1 << 41) /* Explicitly aligned (e.g. MOVDQA) */
#define Unaligned ((u64)1 << 42) /* Explicitly unaligned (e.g. MOVDQU) */
#define Avx ((u64)1 << 43) /* Advanced Vector Extensions */
@@ -887,6 +888,40 @@
ctxt->ops->put_fpu(ctxt);
}
+static void read_mmx_reg(struct x86_emulate_ctxt *ctxt, u64 *data, int reg)
+{
+ ctxt->ops->get_fpu(ctxt);
+ switch (reg) {
+ case 0: asm("movq %%mm0, %0" : "=m"(*data)); break;
+ case 1: asm("movq %%mm1, %0" : "=m"(*data)); break;
+ case 2: asm("movq %%mm2, %0" : "=m"(*data)); break;
+ case 3: asm("movq %%mm3, %0" : "=m"(*data)); break;
+ case 4: asm("movq %%mm4, %0" : "=m"(*data)); break;
+ case 5: asm("movq %%mm5, %0" : "=m"(*data)); break;
+ case 6: asm("movq %%mm6, %0" : "=m"(*data)); break;
+ case 7: asm("movq %%mm7, %0" : "=m"(*data)); break;
+ default: BUG();
+ }
+ ctxt->ops->put_fpu(ctxt);
+}
+
+static void write_mmx_reg(struct x86_emulate_ctxt *ctxt, u64 *data, int reg)
+{
+ ctxt->ops->get_fpu(ctxt);
+ switch (reg) {
+ case 0: asm("movq %0, %%mm0" : : "m"(*data)); break;
+ case 1: asm("movq %0, %%mm1" : : "m"(*data)); break;
+ case 2: asm("movq %0, %%mm2" : : "m"(*data)); break;
+ case 3: asm("movq %0, %%mm3" : : "m"(*data)); break;
+ case 4: asm("movq %0, %%mm4" : : "m"(*data)); break;
+ case 5: asm("movq %0, %%mm5" : : "m"(*data)); break;
+ case 6: asm("movq %0, %%mm6" : : "m"(*data)); break;
+ case 7: asm("movq %0, %%mm7" : : "m"(*data)); break;
+ default: BUG();
+ }
+ ctxt->ops->put_fpu(ctxt);
+}
+
static void decode_register_operand(struct x86_emulate_ctxt *ctxt,
struct operand *op)
{
@@ -903,6 +938,13 @@
read_sse_reg(ctxt, &op->vec_val, reg);
return;
}
+ if (ctxt->d & Mmx) {
+ reg &= 7;
+ op->type = OP_MM;
+ op->bytes = 8;
+ op->addr.mm = reg;
+ return;
+ }
op->type = OP_REG;
if (ctxt->d & ByteOp) {
@@ -948,6 +990,12 @@
read_sse_reg(ctxt, &op->vec_val, ctxt->modrm_rm);
return rc;
}
+ if (ctxt->d & Mmx) {
+ op->type = OP_MM;
+ op->bytes = 8;
+ op->addr.xmm = ctxt->modrm_rm & 7;
+ return rc;
+ }
fetch_register_operand(op);
return rc;
}
@@ -1415,6 +1463,9 @@
case OP_XMM:
write_sse_reg(ctxt, &ctxt->dst.vec_val, ctxt->dst.addr.xmm);
break;
+ case OP_MM:
+ write_mmx_reg(ctxt, &ctxt->dst.mm_val, ctxt->dst.addr.mm);
+ break;
case OP_NONE:
/* no writeback */
break;
@@ -3987,6 +4038,8 @@
if (ctxt->d & Sse)
ctxt->op_bytes = 16;
+ else if (ctxt->d & Mmx)
+ ctxt->op_bytes = 8;
/* ModRM and SIB bytes. */
if (ctxt->d & ModRM) {
@@ -4057,6 +4110,35 @@
return false;
}
+static int flush_pending_x87_faults(struct x86_emulate_ctxt *ctxt)
+{
+ bool fault = false;
+
+ ctxt->ops->get_fpu(ctxt);
+ asm volatile("1: fwait \n\t"
+ "2: \n\t"
+ ".pushsection .fixup,\"ax\" \n\t"
+ "3: \n\t"
+ "movb $1, %[fault] \n\t"
+ "jmp 2b \n\t"
+ ".popsection \n\t"
+ _ASM_EXTABLE(1b, 3b)
+ : [fault]"+rm"(fault));
+ ctxt->ops->put_fpu(ctxt);
+
+ if (unlikely(fault))
+ return emulate_exception(ctxt, MF_VECTOR, 0, false);
+
+ return X86EMUL_CONTINUE;
+}
+
+static void fetch_possible_mmx_operand(struct x86_emulate_ctxt *ctxt,
+ struct operand *op)
+{
+ if (op->type == OP_MM)
+ read_mmx_reg(ctxt, &op->mm_val, op->addr.mm);
+}
+
int x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
{
struct x86_emulate_ops *ops = ctxt->ops;
@@ -4081,18 +4163,31 @@
goto done;
}
- if ((ctxt->d & Sse)
- && ((ops->get_cr(ctxt, 0) & X86_CR0_EM)
- || !(ops->get_cr(ctxt, 4) & X86_CR4_OSFXSR))) {
+ if (((ctxt->d & (Sse|Mmx)) && ((ops->get_cr(ctxt, 0) & X86_CR0_EM)))
+ || ((ctxt->d & Sse) && !(ops->get_cr(ctxt, 4) & X86_CR4_OSFXSR))) {
rc = emulate_ud(ctxt);
goto done;
}
- if ((ctxt->d & Sse) && (ops->get_cr(ctxt, 0) & X86_CR0_TS)) {
+ if ((ctxt->d & (Sse|Mmx)) && (ops->get_cr(ctxt, 0) & X86_CR0_TS)) {
rc = emulate_nm(ctxt);
goto done;
}
+ if (ctxt->d & Mmx) {
+ rc = flush_pending_x87_faults(ctxt);
+ if (rc != X86EMUL_CONTINUE)
+ goto done;
+ /*
+ * Now that we know the fpu is exception safe, we can fetch
+ * operands from it.
+ */
+ fetch_possible_mmx_operand(ctxt, &ctxt->src);
+ fetch_possible_mmx_operand(ctxt, &ctxt->src2);
+ if (!(ctxt->d & Mov))
+ fetch_possible_mmx_operand(ctxt, &ctxt->dst);
+ }
+
if (unlikely(ctxt->guest_mode) && ctxt->intercept) {
rc = emulator_check_intercept(ctxt, ctxt->intercept,
X86_ICPT_PRE_EXCEPT);