KVM: x86 emulator: Decode memory operands directly into a 'struct operand'

Since modrm operand can be either register or memory, decoding it into
a 'struct operand', which can represent both, is simpler.

Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index e425444658e8ea7a66af6a4eecac4ac6e0387296..1e4a72ce301ad848cdd5276b5966911f31938b1d 100644 (file)
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -203,9 +203,6 @@ struct decode_cache {
        u8 modrm_rm;
        u8 modrm_seg;
        bool rip_relative;
-       unsigned long modrm_ea;
-       void *modrm_ptr;
-       unsigned long modrm_val;
        struct fetch_cache fetch;
        struct read_cache io_read;
        struct read_cache mem_read;

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index eda69411d050c501695fcdb36773ca200e0ebabd..955d48074648a2db5562dcea4f02c5d3cc18c8db 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -581,12 +581,14 @@ static void decode_register_operand(struct operand *op,
 }
 
 static int decode_modrm(struct x86_emulate_ctxt *ctxt,
-                       struct x86_emulate_ops *ops)
+                       struct x86_emulate_ops *ops,
+                       struct operand *op)
 {
        struct decode_cache *c = &ctxt->decode;
        u8 sib;
        int index_reg = 0, base_reg = 0, scale;
        int rc = X86EMUL_CONTINUE;
+       ulong modrm_ea = 0;
 
        if (c->rex_prefix) {
                c->modrm_reg = (c->rex_prefix & 4) << 1;        /* REX.R */
@@ -598,16 +600,19 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
        c->modrm_mod |= (c->modrm & 0xc0) >> 6;
        c->modrm_reg |= (c->modrm & 0x38) >> 3;
        c->modrm_rm |= (c->modrm & 0x07);
-       c->modrm_ea = 0;
        c->modrm_seg = VCPU_SREG_DS;
 
        if (c->modrm_mod == 3) {
-               c->modrm_ptr = decode_register(c->modrm_rm,
+               op->type = OP_REG;
+               op->bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
+               op->addr.reg = decode_register(c->modrm_rm,
                                               c->regs, c->d & ByteOp);
-               c->modrm_val = *(unsigned long *)c->modrm_ptr;
+               fetch_register_operand(op);
                return rc;
        }
 
+       op->type = OP_MEM;
+
        if (c->ad_bytes == 2) {
                unsigned bx = c->regs[VCPU_REGS_RBX];
                unsigned bp = c->regs[VCPU_REGS_RBP];
@@ -618,46 +623,46 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
                switch (c->modrm_mod) {
                case 0:
                        if (c->modrm_rm == 6)
-                               c->modrm_ea += insn_fetch(u16, 2, c->eip);
+                               modrm_ea += insn_fetch(u16, 2, c->eip);
                        break;
                case 1:
-                       c->modrm_ea += insn_fetch(s8, 1, c->eip);
+                       modrm_ea += insn_fetch(s8, 1, c->eip);
                        break;
                case 2:
-                       c->modrm_ea += insn_fetch(u16, 2, c->eip);
+                       modrm_ea += insn_fetch(u16, 2, c->eip);
                        break;
                }
                switch (c->modrm_rm) {
                case 0:
-                       c->modrm_ea += bx + si;
+                       modrm_ea += bx + si;
                        break;
                case 1:
-                       c->modrm_ea += bx + di;
+                       modrm_ea += bx + di;
                        break;
                case 2:
-                       c->modrm_ea += bp + si;
+                       modrm_ea += bp + si;
                        break;
                case 3:
-                       c->modrm_ea += bp + di;
+                       modrm_ea += bp + di;
                        break;
                case 4:
-                       c->modrm_ea += si;
+                       modrm_ea += si;
                        break;
                case 5:
-                       c->modrm_ea += di;
+                       modrm_ea += di;
                        break;
                case 6:
                        if (c->modrm_mod != 0)
-                               c->modrm_ea += bp;
+                               modrm_ea += bp;
                        break;
                case 7:
-                       c->modrm_ea += bx;
+                       modrm_ea += bx;
                        break;
                }
                if (c->modrm_rm == 2 || c->modrm_rm == 3 ||
                    (c->modrm_rm == 6 && c->modrm_mod != 0))
                        c->modrm_seg = VCPU_SREG_SS;
-               c->modrm_ea = (u16)c->modrm_ea;
+               modrm_ea = (u16)modrm_ea;
        } else {
                /* 32/64-bit ModR/M decode. */
                if ((c->modrm_rm & 7) == 4) {
@@ -667,48 +672,51 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
                        scale = sib >> 6;
 
                        if ((base_reg & 7) == 5 && c->modrm_mod == 0)
-                               c->modrm_ea += insn_fetch(s32, 4, c->eip);
+                               modrm_ea += insn_fetch(s32, 4, c->eip);
                        else
-                               c->modrm_ea += c->regs[base_reg];
+                               modrm_ea += c->regs[base_reg];
                        if (index_reg != 4)
-                               c->modrm_ea += c->regs[index_reg] << scale;
+                               modrm_ea += c->regs[index_reg] << scale;
                } else if ((c->modrm_rm & 7) == 5 && c->modrm_mod == 0) {
                        if (ctxt->mode == X86EMUL_MODE_PROT64)
                                c->rip_relative = 1;
                } else
-                       c->modrm_ea += c->regs[c->modrm_rm];
+                       modrm_ea += c->regs[c->modrm_rm];
                switch (c->modrm_mod) {
                case 0:
                        if (c->modrm_rm == 5)
-                               c->modrm_ea += insn_fetch(s32, 4, c->eip);
+                               modrm_ea += insn_fetch(s32, 4, c->eip);
                        break;
                case 1:
-                       c->modrm_ea += insn_fetch(s8, 1, c->eip);
+                       modrm_ea += insn_fetch(s8, 1, c->eip);
                        break;
                case 2:
-                       c->modrm_ea += insn_fetch(s32, 4, c->eip);
+                       modrm_ea += insn_fetch(s32, 4, c->eip);
                        break;
                }
        }
+       op->addr.mem = modrm_ea;
 done:
        return rc;
 }
 
 static int decode_abs(struct x86_emulate_ctxt *ctxt,
-                     struct x86_emulate_ops *ops)
+                     struct x86_emulate_ops *ops,
+                     struct operand *op)
 {
        struct decode_cache *c = &ctxt->decode;
        int rc = X86EMUL_CONTINUE;
 
+       op->type = OP_MEM;
        switch (c->ad_bytes) {
        case 2:
-               c->modrm_ea = insn_fetch(u16, 2, c->eip);
+               op->addr.mem = insn_fetch(u16, 2, c->eip);
                break;
        case 4:
-               c->modrm_ea = insn_fetch(u32, 4, c->eip);
+               op->addr.mem = insn_fetch(u32, 4, c->eip);
                break;
        case 8:
-               c->modrm_ea = insn_fetch(u64, 8, c->eip);
+               op->addr.mem = insn_fetch(u64, 8, c->eip);
                break;
        }
 done:
@@ -2280,6 +2288,7 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt)
        int mode = ctxt->mode;
        int def_op_bytes, def_ad_bytes, dual, goffset;
        struct opcode opcode, *g_mod012, *g_mod3;
+       struct operand memop = { .type = OP_NONE };
 
        /* we cannot decode insn before we complete previous rep insn */
        WARN_ON(ctxt->restart);
@@ -2418,25 +2427,25 @@ done_prefixes:
 
        /* ModRM and SIB bytes. */
        if (c->d & ModRM) {
-               rc = decode_modrm(ctxt, ops);
+               rc = decode_modrm(ctxt, ops, &memop);
                if (!c->has_seg_override)
                        set_seg_override(c, c->modrm_seg);
        } else if (c->d & MemAbs)
-               rc = decode_abs(ctxt, ops);
+               rc = decode_abs(ctxt, ops, &memop);
        if (rc != X86EMUL_CONTINUE)
                goto done;
 
        if (!c->has_seg_override)
                set_seg_override(c, VCPU_SREG_DS);
 
-       if (!(!c->twobyte && c->b == 0x8d))
-               c->modrm_ea += seg_override_base(ctxt, ops, c);
+       if (memop.type == OP_MEM && !(!c->twobyte && c->b == 0x8d))
+               memop.addr.mem += seg_override_base(ctxt, ops, c);
 
-       if (c->ad_bytes != 8)
-               c->modrm_ea = (u32)c->modrm_ea;
+       if (memop.type == OP_MEM && c->ad_bytes != 8)
+               memop.addr.mem = (u32)memop.addr.mem;
 
-       if (c->rip_relative)
-               c->modrm_ea += c->eip;
+       if (memop.type == OP_MEM && c->rip_relative)
+               memop.addr.mem += c->eip;
 
        /*
         * Decode and fetch the source operand: register, memory
@@ -2449,31 +2458,16 @@ done_prefixes:
                decode_register_operand(&c->src, c, 0);
                break;
        case SrcMem16:
-               c->src.bytes = 2;
+               memop.bytes = 2;
                goto srcmem_common;
        case SrcMem32:
-               c->src.bytes = 4;
+               memop.bytes = 4;
                goto srcmem_common;
        case SrcMem:
-               c->src.bytes = (c->d & ByteOp) ? 1 :
+               memop.bytes = (c->d & ByteOp) ? 1 :
                                                           c->op_bytes;
-               /* Don't fetch the address for invlpg: it could be unmapped. */
-               if (c->d & NoAccess)
-                       break;
        srcmem_common:
-               /*
-                * For instructions with a ModR/M byte, switch to register
-                * access if Mod = 3.
-                */
-               if ((c->d & ModRM) && c->modrm_mod == 3) {
-                       c->src.type = OP_REG;
-                       c->src.val = c->modrm_val;
-                       c->src.addr.reg = c->modrm_ptr;
-                       break;
-               }
-               c->src.type = OP_MEM;
-               c->src.addr.mem = c->modrm_ea;
-               c->src.val = 0;
+               c->src = memop;
                break;
        case SrcImm:
        case SrcImmU:
@@ -2543,9 +2537,8 @@ done_prefixes:
                insn_fetch_arr(c->src.valptr, c->src.bytes, c->eip);
                break;
        case SrcMemFAddr:
-               c->src.type = OP_MEM;
-               c->src.addr.mem = c->modrm_ea;
-               c->src.bytes = c->op_bytes + 2;
+               memop.bytes = c->op_bytes + 2;
+               goto srcmem_common;
                break;
        }
 
@@ -2583,26 +2576,18 @@ done_prefixes:
                break;
        case DstMem:
        case DstMem64:
-               if ((c->d & ModRM) && c->modrm_mod == 3) {
-                       c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
-                       c->dst.type = OP_REG;
-                       c->dst.val = c->dst.orig_val = c->modrm_val;
-                       c->dst.addr.reg = c->modrm_ptr;
-                       break;
-               }
-               c->dst.type = OP_MEM;
-               c->dst.addr.mem = c->modrm_ea;
+               c->dst = memop;
                if ((c->d & DstMask) == DstMem64)
                        c->dst.bytes = 8;
                else
                        c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
-               c->dst.val = 0;
-               if (c->d & BitOp) {
+               if (c->dst.type == OP_MEM && (c->d & BitOp)) {
                        unsigned long mask = ~(c->dst.bytes * 8 - 1);
 
                        c->dst.addr.mem = c->dst.addr.mem +
                                                   (c->src.val & mask) / 8;
                }
+               c->dst.orig_val = c->dst.val;
                break;
        case DstAcc:
                c->dst.type = OP_REG;
@@ -2682,11 +2667,15 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
        }
 
        if (c->src.type == OP_MEM) {
+               if (c->d & NoAccess)
+                       goto no_fetch;
                rc = read_emulated(ctxt, ops, c->src.addr.mem,
                                        c->src.valptr, c->src.bytes);
                if (rc != X86EMUL_CONTINUE)
                        goto done;
                c->src.orig_val64 = c->src.val64;
+       no_fetch:
+               ;
        }
 
        if (c->src2.type == OP_MEM) {