KVM: x86 emulator: Add 'push/pop sreg' instructions

[avi: avoid buffer overflow]

Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 1be5cd6..1cdfec5 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -92,19 +92,22 @@ static u32 opcode_table[256] = {
        /* 0x00 - 0x07 */
        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
        ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
-       ByteOp | DstAcc | SrcImm, DstAcc | SrcImm, 0, 0,
+       ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
+       ImplicitOps | Stack, ImplicitOps | Stack,
        /* 0x08 - 0x0F */
        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
        ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
-       0, 0, 0, 0,
+       0, 0, ImplicitOps | Stack, 0,
        /* 0x10 - 0x17 */
        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
        ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
-       ByteOp | DstAcc | SrcImm, DstAcc | SrcImm, 0, 0,
+       ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
+       ImplicitOps | Stack, ImplicitOps | Stack,
        /* 0x18 - 0x1F */
        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
        ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
-       ByteOp | DstAcc | SrcImm, DstAcc | SrcImm, 0, 0,
+       ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
+       ImplicitOps | Stack, ImplicitOps | Stack,
        /* 0x20 - 0x27 */
        ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
        ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
@@ -244,11 +247,13 @@ static u32 twobyte_table[256] = {
        /* 0x90 - 0x9F */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
        /* 0xA0 - 0xA7 */
-       0, 0, 0, DstMem | SrcReg | ModRM | BitOp,
+       ImplicitOps | Stack, ImplicitOps | Stack,
+       0, DstMem | SrcReg | ModRM | BitOp,
        DstMem | SrcReg | Src2ImmByte | ModRM,
        DstMem | SrcReg | Src2CL | ModRM, 0, 0,
        /* 0xA8 - 0xAF */
-       0, 0, 0, DstMem | SrcReg | ModRM | BitOp,
+       ImplicitOps | Stack, ImplicitOps | Stack,
+       0, DstMem | SrcReg | ModRM | BitOp,
        DstMem | SrcReg | Src2ImmByte | ModRM,
        DstMem | SrcReg | Src2CL | ModRM,
        ModRM, 0,
@@ -1186,6 +1191,32 @@ static int emulate_pop(struct x86_emulate_ctxt *ctxt,
        return rc;
 }
 
+static void emulate_push_sreg(struct x86_emulate_ctxt *ctxt, int seg)
+{
+       struct decode_cache *c = &ctxt->decode;
+       struct kvm_segment segment;
+
+       kvm_x86_ops->get_segment(ctxt->vcpu, &segment, seg);
+
+       c->src.val = segment.selector;
+       emulate_push(ctxt);
+}
+
+static int emulate_pop_sreg(struct x86_emulate_ctxt *ctxt,
+                            struct x86_emulate_ops *ops, int seg)
+{
+       struct decode_cache *c = &ctxt->decode;
+       unsigned long selector;
+       int rc;
+
+       rc = emulate_pop(ctxt, ops, &selector, c->op_bytes);
+       if (rc != 0)
+               return rc;
+
+       rc = kvm_load_segment_descriptor(ctxt->vcpu, (u16)selector, 1, seg);
+       return rc;
+}
+
 static inline int emulate_grp1a(struct x86_emulate_ctxt *ctxt,
                                struct x86_emulate_ops *ops)
 {
@@ -1707,18 +1738,66 @@ special_insn:
              add:              /* add */
                emulate_2op_SrcV("add", c->src, c->dst, ctxt->eflags);
                break;
+       case 0x06:              /* push es */
+               if (ctxt->mode == X86EMUL_MODE_PROT64)
+                       goto cannot_emulate;
+
+               emulate_push_sreg(ctxt, VCPU_SREG_ES);
+               break;
+       case 0x07:              /* pop es */
+                if (ctxt->mode == X86EMUL_MODE_PROT64)
+                        goto cannot_emulate;
+
+               rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_ES);
+               if (rc != 0)
+                       goto done;
+               break;
        case 0x08 ... 0x0d:
              or:               /* or */
                emulate_2op_SrcV("or", c->src, c->dst, ctxt->eflags);
                break;
+       case 0x0e:              /* push cs */
+                if (ctxt->mode == X86EMUL_MODE_PROT64)
+                        goto cannot_emulate;
+
+               emulate_push_sreg(ctxt, VCPU_SREG_CS);
+               break;
        case 0x10 ... 0x15:
              adc:              /* adc */
                emulate_2op_SrcV("adc", c->src, c->dst, ctxt->eflags);
                break;
+       case 0x16:              /* push ss */
+                if (ctxt->mode == X86EMUL_MODE_PROT64)
+                        goto cannot_emulate;
+
+               emulate_push_sreg(ctxt, VCPU_SREG_SS);
+               break;
+       case 0x17:              /* pop ss */
+                if (ctxt->mode == X86EMUL_MODE_PROT64)
+                        goto cannot_emulate;
+
+               rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_SS);
+               if (rc != 0)
+                       goto done;
+               break;
        case 0x18 ... 0x1d:
              sbb:              /* sbb */
                emulate_2op_SrcV("sbb", c->src, c->dst, ctxt->eflags);
                break;
+       case 0x1e:              /* push ds */
+                if (ctxt->mode == X86EMUL_MODE_PROT64)
+                        goto cannot_emulate;
+
+               emulate_push_sreg(ctxt, VCPU_SREG_DS);
+               break;
+       case 0x1f:              /* pop ds */
+                if (ctxt->mode == X86EMUL_MODE_PROT64)
+                        goto cannot_emulate;
+
+               rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_DS);
+               if (rc != 0)
+                       goto done;
+               break;
        case 0x20 ... 0x25:
              and:              /* and */
                emulate_2op_SrcV("and", c->src, c->dst, ctxt->eflags);
@@ -2297,6 +2376,14 @@ twobyte_insn:
                        jmp_rel(c, c->src.val);
                c->dst.type = OP_NONE;
                break;
+       case 0xa0:        /* push fs */
+               emulate_push_sreg(ctxt, VCPU_SREG_FS);
+               break;
+       case 0xa1:       /* pop fs */
+               rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_FS);
+               if (rc != 0)
+                       goto done;
+               break;
        case 0xa3:
              bt:               /* bt */
                c->dst.type = OP_NONE;
@@ -2308,6 +2395,14 @@ twobyte_insn:
        case 0xa5: /* shld cl, r, r/m */
                emulate_2op_cl("shld", c->src2, c->src, c->dst, ctxt->eflags);
                break;
+       case 0xa8:      /* push gs */
+               emulate_push_sreg(ctxt, VCPU_SREG_GS);
+               break;
+       case 0xa9:      /* pop gs */
+               rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_GS);
+               if (rc != 0)
+                       goto done;
+               break;
        case 0xab:
              bts:              /* bts */
                /* only subword offset */