diff options
Diffstat (limited to 'arch/x86/kvm/emulate.c')
| -rw-r--r-- | arch/x86/kvm/emulate.c | 39 |
1 files changed, 33 insertions, 6 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 8079d141792a..e7d04d0c8008 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -4014,6 +4014,26 @@ static int em_fxsave(struct x86_emulate_ctxt *ctxt) fxstate_size(ctxt)); } +/* + * FXRSTOR might restore XMM registers not provided by the guest. Fill + * in the host registers (via FXSAVE) instead, so they won't be modified. + * (preemption has to stay disabled until FXRSTOR). + * + * Use noinline to keep the stack for other functions called by callers small. + */ +static noinline int fxregs_fixup(struct fxregs_state *fx_state, + const size_t used_size) +{ + struct fxregs_state fx_tmp; + int rc; + + rc = asm_safe("fxsave %[fx]", , [fx] "+m"(fx_tmp)); + memcpy((void *)fx_state + used_size, (void *)&fx_tmp + used_size, + __fxstate_size(16) - used_size); + + return rc; +} + static int em_fxrstor(struct x86_emulate_ctxt *ctxt) { struct fxregs_state fx_state; @@ -4024,19 +4044,19 @@ static int em_fxrstor(struct x86_emulate_ctxt *ctxt) if (rc != X86EMUL_CONTINUE) return rc; + size = fxstate_size(ctxt); + rc = segmented_read_std(ctxt, ctxt->memop.addr.mem, &fx_state, size); + if (rc != X86EMUL_CONTINUE) + return rc; + ctxt->ops->get_fpu(ctxt); - size = fxstate_size(ctxt); if (size < __fxstate_size(16)) { - rc = asm_safe("fxsave %[fx]", , [fx] "+m"(fx_state)); + rc = fxregs_fixup(&fx_state, size); if (rc != X86EMUL_CONTINUE) goto out; } - rc = segmented_read_std(ctxt, ctxt->memop.addr.mem, &fx_state, size); - if (rc != X86EMUL_CONTINUE) - goto out; - if (fx_state.mxcsr >> 16) { rc = emulate_gp(ctxt, 0); goto out; @@ -5000,6 +5020,8 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len) bool op_prefix = false; bool has_seg_override = false; struct opcode opcode; + u16 dummy; + struct desc_struct desc; ctxt->memop.type = OP_NONE; ctxt->memopp = NULL; @@ -5018,6 +5040,11 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len) switch (mode) { case X86EMUL_MODE_REAL: case X86EMUL_MODE_VM86: + def_op_bytes = def_ad_bytes = 2; + ctxt->ops->get_segment(ctxt, &dummy, &desc, NULL, VCPU_SREG_CS); + if (desc.d) + def_op_bytes = def_ad_bytes = 4; + break; case X86EMUL_MODE_PROT16: def_op_bytes = def_ad_bytes = 2; break; |