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KVM: x86 emulator: Add Virtual-8086 mode of emulation 

For some instructions CPU behaves differently for real-mode and
virtual 8086. Let emulator know which mode cpu is in, so it will
not poke into vcpu state directly.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Gleb Natapov 2010-02-10 14:21:31 +02:00 committed by Marcelo Tosatti
parent 60a29d4ea4
commit a004475567
3 changed files with 10 additions and 6 deletions
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1
arch/x86/include/asm/kvm_emulate.h
View File

@ -168,6 +168,7 @@ struct x86_emulate_ctxt {
/* Execution mode, passed to the emulator. */
#define X86EMUL_MODE_REAL 0 /* Real mode. */
#define X86EMUL_MODE_VM86 1 /* Virtual 8086 mode. */
#define X86EMUL_MODE_PROT16 2 /* 16-bit protected mode. */
#define X86EMUL_MODE_PROT32 4 /* 32-bit protected mode. */
#define X86EMUL_MODE_PROT64 8 /* 64-bit (long) mode. */

12
arch/x86/kvm/emulate.c
View File

@ -899,6 +899,7 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
switch (mode) {
case X86EMUL_MODE_REAL:
case X86EMUL_MODE_VM86:
case X86EMUL_MODE_PROT16:
def_op_bytes = def_ad_bytes = 2;
break;
@ -1525,7 +1526,7 @@ emulate_syscall(struct x86_emulate_ctxt *ctxt)
/* syscall is not available in real mode */
if (c->lock_prefix || ctxt->mode == X86EMUL_MODE_REAL
|| !is_protmode(ctxt->vcpu))
|| ctxt->mode == X86EMUL_MODE_VM86)
return -1;
setup_syscalls_segments(ctxt, &cs, &ss);
@ -1577,8 +1578,8 @@ emulate_sysenter(struct x86_emulate_ctxt *ctxt)
if (c->lock_prefix)
return -1;
/* inject #GP if in real mode or paging is disabled */
if (ctxt->mode == X86EMUL_MODE_REAL || !is_protmode(ctxt->vcpu)) {
/* inject #GP if in real mode */
if (ctxt->mode == X86EMUL_MODE_REAL) {
kvm_inject_gp(ctxt->vcpu, 0);
return -1;
}
@ -1642,8 +1643,9 @@ emulate_sysexit(struct x86_emulate_ctxt *ctxt)
if (c->lock_prefix)
return -1;
/* inject #GP if in real mode or paging is disabled */
if (ctxt->mode == X86EMUL_MODE_REAL || !is_protmode(ctxt->vcpu)) {
/* inject #GP if in real mode or Virtual 8086 mode */
if (ctxt->mode == X86EMUL_MODE_REAL ||
ctxt->mode == X86EMUL_MODE_VM86) {
kvm_inject_gp(ctxt->vcpu, 0);
return -1;
}

3
arch/x86/kvm/x86.c
View File

@ -3348,8 +3348,9 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
vcpu->arch.emulate_ctxt.vcpu = vcpu;
vcpu->arch.emulate_ctxt.eflags = kvm_get_rflags(vcpu);
vcpu->arch.emulate_ctxt.mode =
(!is_protmode(vcpu)) ? X86EMUL_MODE_REAL :
(vcpu->arch.emulate_ctxt.eflags & X86_EFLAGS_VM)
? X86EMUL_MODE_REAL : cs_l
? X86EMUL_MODE_VM86 : cs_l
? X86EMUL_MODE_PROT64 : cs_db
? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;