Commit 4d2179e1 authored by Gleb Natapov's avatar Gleb Natapov Committed by Avi Kivity
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KVM: x86 emulator: handle shadowed registers outside emulator 



Emulator shouldn't access vcpu directly.

Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent bdb475a3

arch/x86/kvm/emulate.c

+0 −15
Original line number Diff line number Diff line
@@ -941,12 +941,9 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) 
	/* we cannot decode insn before we complete previous rep insn */

	WARN_ON(ctxt->restart);



	/* Shadow copy of register state. Committed on successful emulation. */

	memset(c, 0, sizeof(struct decode_cache));

	c->eip = ctxt->eip;

	c->fetch.start = c->fetch.end = c->eip;

	ctxt->cs_base = seg_base(ctxt, ops, VCPU_SREG_CS);

	memcpy(c->regs, ctxt->vcpu->arch.regs, sizeof c->regs);



	switch (mode) {

	case X86EMUL_MODE_REAL:
@@ -2486,16 +2483,13 @@ int emulator_task_switch(struct x86_emulate_ctxt *ctxt, 
	struct decode_cache *c = &ctxt->decode;

	int rc;



	memset(c, 0, sizeof(struct decode_cache));

	c->eip = ctxt->eip;

	memcpy(c->regs, ctxt->vcpu->arch.regs, sizeof c->regs);

	c->dst.type = OP_NONE;



	rc = emulator_do_task_switch(ctxt, ops, tss_selector, reason,

				     has_error_code, error_code);



	if (rc == X86EMUL_CONTINUE) {

		memcpy(ctxt->vcpu->arch.regs, c->regs, sizeof c->regs);

		rc = writeback(ctxt, ops);

		if (rc == X86EMUL_CONTINUE)

			ctxt->eip = c->eip;
@@ -2525,13 +2519,6 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) 
	ctxt->interruptibility = 0;

	ctxt->decode.mem_read.pos = 0;



	/* Shadow copy of register state. Committed on successful emulation.

	 * NOTE: we can copy them from vcpu as x86_decode_insn() doesn't

	 * modify them.

	 */



	memcpy(c->regs, ctxt->vcpu->arch.regs, sizeof c->regs);



	if (ctxt->mode == X86EMUL_MODE_PROT64 && (c->d & No64)) {

		kvm_queue_exception(ctxt->vcpu, UD_VECTOR);

		goto done;
@@ -3031,8 +3018,6 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) 
	 * without decoding

	 */

	ctxt->decode.mem_read.end = 0;

	/* Commit shadow register state. */

	memcpy(ctxt->vcpu->arch.regs, c->regs, sizeof c->regs);

	ctxt->eip = c->eip;



done:

arch/x86/kvm/x86.c

+12 −2
Original line number Diff line number Diff line
@@ -3844,7 +3844,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu, 
			int emulation_type)

{

	int r, shadow_mask;

	struct decode_cache *c;

	struct decode_cache *c = &vcpu->arch.emulate_ctxt.decode;



	kvm_clear_exception_queue(vcpu);

	vcpu->arch.mmio_fault_cr2 = cr2;
@@ -3869,13 +3869,14 @@ int emulate_instruction(struct kvm_vcpu *vcpu, 
			? X86EMUL_MODE_VM86 : cs_l

			? X86EMUL_MODE_PROT64 :	cs_db

			? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;

		memset(c, 0, sizeof(struct decode_cache));

		memcpy(c->regs, vcpu->arch.regs, sizeof c->regs);



		r = x86_decode_insn(&vcpu->arch.emulate_ctxt, &emulate_ops);

		trace_kvm_emulate_insn_start(vcpu);



		/* Only allow emulation of specific instructions on #UD

		 * (namely VMMCALL, sysenter, sysexit, syscall)*/

		c = &vcpu->arch.emulate_ctxt.decode;

		if (emulation_type & EMULTYPE_TRAP_UD) {

			if (!c->twobyte)

				return EMULATE_FAIL;
@@ -3916,6 +3917,10 @@ int emulate_instruction(struct kvm_vcpu *vcpu, 
		return EMULATE_DONE;

	}



	/* this is needed for vmware backdor interface to work since it

	   changes registers values  during IO operation */

	memcpy(c->regs, vcpu->arch.regs, sizeof c->regs);



restart:

	r = x86_emulate_insn(&vcpu->arch.emulate_ctxt, &emulate_ops);
@@ -3936,6 +3941,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu, 
	shadow_mask = vcpu->arch.emulate_ctxt.interruptibility;

	kvm_x86_ops->set_interrupt_shadow(vcpu, shadow_mask);

	kvm_x86_ops->set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags);

	memcpy(vcpu->arch.regs, c->regs, sizeof c->regs);

	kvm_rip_write(vcpu, vcpu->arch.emulate_ctxt.eip);



	if (vcpu->arch.pio.count) {
@@ -4919,6 +4925,7 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu, 
int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason,

		    bool has_error_code, u32 error_code)

{

	struct decode_cache *c = &vcpu->arch.emulate_ctxt.decode;

	int cs_db, cs_l, ret;

	cache_all_regs(vcpu);
@@ -4933,6 +4940,8 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason, 
		? X86EMUL_MODE_VM86 : cs_l

		? X86EMUL_MODE_PROT64 :	cs_db

		? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;

	memset(c, 0, sizeof(struct decode_cache));

	memcpy(c->regs, vcpu->arch.regs, sizeof c->regs);



	ret = emulator_task_switch(&vcpu->arch.emulate_ctxt, &emulate_ops,

				   tss_selector, reason, has_error_code,
@@ -4941,6 +4950,7 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason, 
	if (ret)

		return EMULATE_FAIL;



	memcpy(vcpu->arch.regs, c->regs, sizeof c->regs);

	kvm_rip_write(vcpu, vcpu->arch.emulate_ctxt.eip);

	kvm_x86_ops->set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags);

	return EMULATE_DONE;