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Commit a0044755 authored by Gleb Natapov's avatar Gleb Natapov Committed by Marcelo Tosatti
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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: default avatarGleb Natapov <gleb@redhat.com>
Cc: stable@kernel.org
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 60a29d4e

arch/x86/include/asm/kvm_emulate.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -168,6 +168,7 @@ struct x86_emulate_ctxt { 




/* Execution mode, passed to the emulator. */

/* Execution mode, passed to the emulator. */

#define X86EMUL_MODE_REAL     0	/* Real mode.             */

#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_PROT16   2	/* 16-bit protected mode. */

#define X86EMUL_MODE_PROT32   4	/* 32-bit protected mode. */

#define X86EMUL_MODE_PROT32   4	/* 32-bit protected mode. */

#define X86EMUL_MODE_PROT64   8	/* 64-bit (long) mode.    */

#define X86EMUL_MODE_PROT64   8	/* 64-bit (long) mode.    */

arch/x86/kvm/emulate.c

+7 −5
Original line number Original line Diff line number Diff line
@@ -899,6 +899,7 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) 




	switch (mode) {

	switch (mode) {

	case X86EMUL_MODE_REAL:

	case X86EMUL_MODE_REAL:

	case X86EMUL_MODE_VM86:

	case X86EMUL_MODE_PROT16:

	case X86EMUL_MODE_PROT16:

		def_op_bytes = def_ad_bytes = 2;

		def_op_bytes = def_ad_bytes = 2;

		break;

		break;
@@ -1525,7 +1526,7 @@ emulate_syscall(struct x86_emulate_ctxt *ctxt) 




	/* syscall is not available in real mode */

	/* syscall is not available in real mode */

	if (c->lock_prefix || ctxt->mode == X86EMUL_MODE_REAL

	if (c->lock_prefix || ctxt->mode == X86EMUL_MODE_REAL

	    || !is_protmode(ctxt->vcpu))

	    || ctxt->mode == X86EMUL_MODE_VM86)

		return -1;

		return -1;





	setup_syscalls_segments(ctxt, &cs, &ss);

	setup_syscalls_segments(ctxt, &cs, &ss);
@@ -1577,8 +1578,8 @@ emulate_sysenter(struct x86_emulate_ctxt *ctxt) 
	if (c->lock_prefix)

	if (c->lock_prefix)

		return -1;

		return -1;





	/* inject #GP if in real mode or paging is disabled */

	/* inject #GP if in real mode */

	if (ctxt->mode == X86EMUL_MODE_REAL || !is_protmode(ctxt->vcpu)) {

	if (ctxt->mode == X86EMUL_MODE_REAL) {

		kvm_inject_gp(ctxt->vcpu, 0);

		kvm_inject_gp(ctxt->vcpu, 0);

		return -1;

		return -1;

	}

	}
@@ -1642,8 +1643,9 @@ emulate_sysexit(struct x86_emulate_ctxt *ctxt) 
	if (c->lock_prefix)

	if (c->lock_prefix)

		return -1;

		return -1;





	/* inject #GP if in real mode or paging is disabled */

	/* inject #GP if in real mode or Virtual 8086 mode */

	if (ctxt->mode == X86EMUL_MODE_REAL || !is_protmode(ctxt->vcpu)) {

	if (ctxt->mode == X86EMUL_MODE_REAL ||

	    ctxt->mode == X86EMUL_MODE_VM86) {

		kvm_inject_gp(ctxt->vcpu, 0);

		kvm_inject_gp(ctxt->vcpu, 0);

		return -1;

		return -1;

	}

	}

arch/x86/kvm/x86.c

+2 −1
Original line number Original line Diff line number Diff line
@@ -3348,8 +3348,9 @@ int emulate_instruction(struct kvm_vcpu *vcpu, 
		vcpu->arch.emulate_ctxt.vcpu = vcpu;

		vcpu->arch.emulate_ctxt.vcpu = vcpu;

		vcpu->arch.emulate_ctxt.eflags = kvm_get_rflags(vcpu);

		vcpu->arch.emulate_ctxt.eflags = kvm_get_rflags(vcpu);

		vcpu->arch.emulate_ctxt.mode =

		vcpu->arch.emulate_ctxt.mode =

			(!is_protmode(vcpu)) ? X86EMUL_MODE_REAL :

			(vcpu->arch.emulate_ctxt.eflags & X86_EFLAGS_VM)

			(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_PROT64 :	cs_db

			? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;

			? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;