KVM: x86: BSF and BSR emulation change register unnecassarily

[karo-tx-linux.git] / arch / x86 / kvm / emulate.c

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 106c01557f2b63706eca28e462a3b072b590f0c5..70045779c72503757899bed6890d9903fc97d699 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -478,6 +478,25 @@ static void assign_masked(ulong *dest, ulong src, ulong mask)
        *dest = (*dest & ~mask) | (src & mask);
 }
 
+static void assign_register(unsigned long *reg, u64 val, int bytes)
+{
+       /* The 4-byte case *is* correct: in 64-bit mode we zero-extend. */
+       switch (bytes) {
+       case 1:
+               *(u8 *)reg = (u8)val;
+               break;
+       case 2:
+               *(u16 *)reg = (u16)val;
+               break;
+       case 4:
+               *reg = (u32)val;
+               break;  /* 64b: zero-extend */
+       case 8:
+               *reg = val;
+               break;
+       }
+}
+
 static inline unsigned long ad_mask(struct x86_emulate_ctxt *ctxt)
 {
        return (1UL << (ctxt->ad_bytes << 3)) - 1;
@@ -943,6 +962,22 @@ FASTOP2(xadd);
 
 FASTOP2R(cmp, cmp_r);
 
+static int em_bsf_c(struct x86_emulate_ctxt *ctxt)
+{
+       /* If src is zero, do not writeback, but update flags */
+       if (ctxt->src.val == 0)
+               ctxt->dst.type = OP_NONE;
+       return fastop(ctxt, em_bsf);
+}
+
+static int em_bsr_c(struct x86_emulate_ctxt *ctxt)
+{
+       /* If src is zero, do not writeback, but update flags */
+       if (ctxt->src.val == 0)
+               ctxt->dst.type = OP_NONE;
+       return fastop(ctxt, em_bsr);
+}
+
 static u8 test_cc(unsigned int condition, unsigned long flags)
 {
        u8 rc;
@@ -1691,21 +1726,7 @@ static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
 
 static void write_register_operand(struct operand *op)
 {
-       /* The 4-byte case *is* correct: in 64-bit mode we zero-extend. */
-       switch (op->bytes) {
-       case 1:
-               *(u8 *)op->addr.reg = (u8)op->val;
-               break;
-       case 2:
-               *(u16 *)op->addr.reg = (u16)op->val;
-               break;
-       case 4:
-               *op->addr.reg = (u32)op->val;
-               break;  /* 64b: zero-extend */
-       case 8:
-               *op->addr.reg = op->val;
-               break;
-       }
+       return assign_register(op->addr.reg, op->val, op->bytes);
 }
 
 static int writeback(struct x86_emulate_ctxt *ctxt, struct operand *op)
@@ -1926,6 +1947,7 @@ static int em_popa(struct x86_emulate_ctxt *ctxt)
 {
        int rc = X86EMUL_CONTINUE;
        int reg = VCPU_REGS_RDI;
+       u32 val;
 
        while (reg >= VCPU_REGS_RAX) {
                if (reg == VCPU_REGS_RSP) {
@@ -1933,9 +1955,10 @@ static int em_popa(struct x86_emulate_ctxt *ctxt)
                        --reg;
                }
 
-               rc = emulate_pop(ctxt, reg_rmw(ctxt, reg), ctxt->op_bytes);
+               rc = emulate_pop(ctxt, &val, ctxt->op_bytes);
                if (rc != X86EMUL_CONTINUE)
                        break;
+               assign_register(reg_rmw(ctxt, reg), val, ctxt->op_bytes);
                --reg;
        }
        return rc;
@@ -3323,7 +3346,7 @@ static int em_clts(struct x86_emulate_ctxt *ctxt)
        return X86EMUL_CONTINUE;
 }
 
-static int em_vmcall(struct x86_emulate_ctxt *ctxt)
+static int em_hypercall(struct x86_emulate_ctxt *ctxt)
 {
        int rc = ctxt->ops->fix_hypercall(ctxt);
 
@@ -3395,17 +3418,6 @@ static int em_lgdt(struct x86_emulate_ctxt *ctxt)
        return em_lgdt_lidt(ctxt, true);
 }
 
-static int em_vmmcall(struct x86_emulate_ctxt *ctxt)
-{
-       int rc;
-
-       rc = ctxt->ops->fix_hypercall(ctxt);
-
-       /* Disable writeback. */
-       ctxt->dst.type = OP_NONE;
-       return rc;
-}
-
 static int em_lidt(struct x86_emulate_ctxt *ctxt)
 {
        return em_lgdt_lidt(ctxt, false);
@@ -3769,7 +3781,7 @@ static int check_perm_out(struct x86_emulate_ctxt *ctxt)
 
 static const struct opcode group7_rm0[] = {
        N,
-       I(SrcNone | Priv | EmulateOnUD, em_vmcall),
+       I(SrcNone | Priv | EmulateOnUD, em_hypercall),
        N, N, N, N, N, N,
 };
 
@@ -3781,7 +3793,7 @@ static const struct opcode group7_rm1[] = {
 
 static const struct opcode group7_rm3[] = {
        DIP(SrcNone | Prot | Priv,              vmrun,          check_svme_pa),
-       II(SrcNone  | Prot | EmulateOnUD,       em_vmmcall,     vmmcall),
+       II(SrcNone  | Prot | EmulateOnUD,       em_hypercall,   vmmcall),
        DIP(SrcNone | Prot | Priv,              vmload,         check_svme_pa),
        DIP(SrcNone | Prot | Priv,              vmsave,         check_svme_pa),
        DIP(SrcNone | Prot | Priv,              stgi,           check_svme),
@@ -4192,7 +4204,8 @@ static const struct opcode twobyte_table[256] = {
        N, N,
        G(BitOp, group8),
        F(DstMem | SrcReg | ModRM | BitOp | Lock | PageTable, em_btc),
-       F(DstReg | SrcMem | ModRM, em_bsf), F(DstReg | SrcMem | ModRM, em_bsr),
+       I(DstReg | SrcMem | ModRM, em_bsf_c),
+       I(DstReg | SrcMem | ModRM, em_bsr_c),
        D(DstReg | SrcMem8 | ModRM | Mov), D(DstReg | SrcMem16 | ModRM | Mov),
        /* 0xC0 - 0xC7 */
        F2bv(DstMem | SrcReg | ModRM | SrcWrite | Lock, em_xadd),
@@ -5137,8 +5150,7 @@ twobyte_insn:
        case 0x40 ... 0x4f:     /* cmov */
                if (test_cc(ctxt->b, ctxt->eflags))
                        ctxt->dst.val = ctxt->src.val;
-               else if (ctxt->mode != X86EMUL_MODE_PROT64 ||
-                        ctxt->op_bytes != 4)
+               else if (ctxt->op_bytes != 4)
                        ctxt->dst.type = OP_NONE; /* no writeback */
                break;
        case 0x80 ... 0x8f: /* jnz rel, etc*/