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Commit 91586a3b authored by Jan Kiszka's avatar Jan Kiszka Committed by Avi Kivity
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KVM: x86: Rework guest single-step flag injection and filtering 



Push TF and RF injection and filtering on guest single-stepping into the
vender get/set_rflags callbacks. This makes the whole mechanism more
robust wrt user space IOCTL order and instruction emulations.

Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent a68a6a72

arch/x86/include/asm/kvm_host.h

+3 −0
Original line number Diff line number Diff line
@@ -614,6 +614,9 @@ void kvm_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l); 
int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata);

int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data);



unsigned long kvm_get_rflags(struct kvm_vcpu *vcpu);

void kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags);



void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr);

void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);

void kvm_inject_page_fault(struct kvm_vcpu *vcpu, unsigned long cr2,

arch/x86/kvm/x86.c

+45 −32
Original line number Diff line number Diff line
@@ -235,6 +235,25 @@ bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl) 
}

EXPORT_SYMBOL_GPL(kvm_require_cpl);



unsigned long kvm_get_rflags(struct kvm_vcpu *vcpu)

{

	unsigned long rflags;



	rflags = kvm_x86_ops->get_rflags(vcpu);

	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)

		rflags &= ~(unsigned long)(X86_EFLAGS_TF | X86_EFLAGS_RF);

	return rflags;

}

EXPORT_SYMBOL_GPL(kvm_get_rflags);



void kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)

{

	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)

		rflags |= X86_EFLAGS_TF | X86_EFLAGS_RF;

	kvm_x86_ops->set_rflags(vcpu, rflags);

}

EXPORT_SYMBOL_GPL(kvm_set_rflags);



/*

 * Load the pae pdptrs.  Return true is they are all valid.

 */
@@ -2777,7 +2796,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu, 
		kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);



		vcpu->arch.emulate_ctxt.vcpu = vcpu;

		vcpu->arch.emulate_ctxt.eflags = kvm_x86_ops->get_rflags(vcpu);

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

		vcpu->arch.emulate_ctxt.mode =

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

			? X86EMUL_MODE_REAL : cs_l
@@ -2855,7 +2874,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu, 
		return EMULATE_DO_MMIO;

	}



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

	kvm_set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags);



	if (vcpu->mmio_is_write) {

		vcpu->mmio_needed = 0;
@@ -3291,7 +3310,7 @@ void realmode_lmsw(struct kvm_vcpu *vcpu, unsigned long msw, 
		   unsigned long *rflags)

{

	kvm_lmsw(vcpu, msw);

	*rflags = kvm_x86_ops->get_rflags(vcpu);

	*rflags = kvm_get_rflags(vcpu);

}



unsigned long realmode_get_cr(struct kvm_vcpu *vcpu, int cr)
@@ -3329,7 +3348,7 @@ void realmode_set_cr(struct kvm_vcpu *vcpu, int cr, unsigned long val, 
	switch (cr) {

	case 0:

		kvm_set_cr0(vcpu, mk_cr_64(vcpu->arch.cr0, val));

		*rflags = kvm_x86_ops->get_rflags(vcpu);

		*rflags = kvm_get_rflags(vcpu);

		break;

	case 2:

		vcpu->arch.cr2 = val;
@@ -3460,7 +3479,7 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu) 
{

	struct kvm_run *kvm_run = vcpu->run;



	kvm_run->if_flag = (kvm_x86_ops->get_rflags(vcpu) & X86_EFLAGS_IF) != 0;

	kvm_run->if_flag = (kvm_get_rflags(vcpu) & X86_EFLAGS_IF) != 0;

	kvm_run->cr8 = kvm_get_cr8(vcpu);

	kvm_run->apic_base = kvm_get_apic_base(vcpu);

	if (irqchip_in_kernel(vcpu->kvm))
@@ -3840,13 +3859,7 @@ int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs) 
#endif



	regs->rip = kvm_rip_read(vcpu);

	regs->rflags = kvm_x86_ops->get_rflags(vcpu);



	/*

	 * Don't leak debug flags in case they were set for guest debugging

	 */

	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)

		regs->rflags &= ~(X86_EFLAGS_TF | X86_EFLAGS_RF);

	regs->rflags = kvm_get_rflags(vcpu);



	vcpu_put(vcpu);
@@ -3874,12 +3887,10 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs) 
	kvm_register_write(vcpu, VCPU_REGS_R13, regs->r13);

	kvm_register_write(vcpu, VCPU_REGS_R14, regs->r14);

	kvm_register_write(vcpu, VCPU_REGS_R15, regs->r15);



#endif



	kvm_rip_write(vcpu, regs->rip);

	kvm_x86_ops->set_rflags(vcpu, regs->rflags);



	kvm_set_rflags(vcpu, regs->rflags);



	vcpu->arch.exception.pending = false;
@@ -4098,7 +4109,7 @@ static int is_vm86_segment(struct kvm_vcpu *vcpu, int seg) 
{

	return (seg != VCPU_SREG_LDTR) &&

		(seg != VCPU_SREG_TR) &&

		(kvm_x86_ops->get_rflags(vcpu) & X86_EFLAGS_VM);

		(kvm_get_rflags(vcpu) & X86_EFLAGS_VM);

}



int kvm_load_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
@@ -4126,7 +4137,7 @@ static void save_state_to_tss32(struct kvm_vcpu *vcpu, 
{

	tss->cr3 = vcpu->arch.cr3;

	tss->eip = kvm_rip_read(vcpu);

	tss->eflags = kvm_x86_ops->get_rflags(vcpu);

	tss->eflags = kvm_get_rflags(vcpu);

	tss->eax = kvm_register_read(vcpu, VCPU_REGS_RAX);

	tss->ecx = kvm_register_read(vcpu, VCPU_REGS_RCX);

	tss->edx = kvm_register_read(vcpu, VCPU_REGS_RDX);
@@ -4150,7 +4161,7 @@ static int load_state_from_tss32(struct kvm_vcpu *vcpu, 
	kvm_set_cr3(vcpu, tss->cr3);



	kvm_rip_write(vcpu, tss->eip);

	kvm_x86_ops->set_rflags(vcpu, tss->eflags | 2);

	kvm_set_rflags(vcpu, tss->eflags | 2);



	kvm_register_write(vcpu, VCPU_REGS_RAX, tss->eax);

	kvm_register_write(vcpu, VCPU_REGS_RCX, tss->ecx);
@@ -4188,7 +4199,7 @@ static void save_state_to_tss16(struct kvm_vcpu *vcpu, 
				struct tss_segment_16 *tss)

{

	tss->ip = kvm_rip_read(vcpu);

	tss->flag = kvm_x86_ops->get_rflags(vcpu);

	tss->flag = kvm_get_rflags(vcpu);

	tss->ax = kvm_register_read(vcpu, VCPU_REGS_RAX);

	tss->cx = kvm_register_read(vcpu, VCPU_REGS_RCX);

	tss->dx = kvm_register_read(vcpu, VCPU_REGS_RDX);
@@ -4209,7 +4220,7 @@ static int load_state_from_tss16(struct kvm_vcpu *vcpu, 
				 struct tss_segment_16 *tss)

{

	kvm_rip_write(vcpu, tss->ip);

	kvm_x86_ops->set_rflags(vcpu, tss->flag | 2);

	kvm_set_rflags(vcpu, tss->flag | 2);

	kvm_register_write(vcpu, VCPU_REGS_RAX, tss->ax);

	kvm_register_write(vcpu, VCPU_REGS_RCX, tss->cx);

	kvm_register_write(vcpu, VCPU_REGS_RDX, tss->dx);
@@ -4355,8 +4366,8 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason) 
	}



	if (reason == TASK_SWITCH_IRET) {

		u32 eflags = kvm_x86_ops->get_rflags(vcpu);

		kvm_x86_ops->set_rflags(vcpu, eflags & ~X86_EFLAGS_NT);

		u32 eflags = kvm_get_rflags(vcpu);

		kvm_set_rflags(vcpu, eflags & ~X86_EFLAGS_NT);

	}



	/* set back link to prev task only if NT bit is set in eflags
@@ -4377,8 +4388,8 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason) 
					 old_tss_base, &nseg_desc);



	if (reason == TASK_SWITCH_CALL || reason == TASK_SWITCH_GATE) {

		u32 eflags = kvm_x86_ops->get_rflags(vcpu);

		kvm_x86_ops->set_rflags(vcpu, eflags | X86_EFLAGS_NT);

		u32 eflags = kvm_get_rflags(vcpu);

		kvm_set_rflags(vcpu, eflags | X86_EFLAGS_NT);

	}



	if (reason != TASK_SWITCH_IRET) {
@@ -4473,12 +4484,15 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, 
					struct kvm_guest_debug *dbg)

{

	unsigned long rflags;

	int old_debug;

	int i;



	vcpu_load(vcpu);



	old_debug = vcpu->guest_debug;

	/*

	 * Read rflags as long as potentially injected trace flags are still

	 * filtered out.

	 */

	rflags = kvm_get_rflags(vcpu);



	vcpu->guest_debug = dbg->control;

	if (!(vcpu->guest_debug & KVM_GUESTDBG_ENABLE))
@@ -4495,12 +4509,11 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, 
		vcpu->arch.switch_db_regs = (vcpu->arch.dr7 & DR7_BP_EN_MASK);

	}



	rflags = kvm_x86_ops->get_rflags(vcpu);

	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)

		rflags |= X86_EFLAGS_TF | X86_EFLAGS_RF;

	else if (old_debug & KVM_GUESTDBG_SINGLESTEP)

		rflags &= ~(X86_EFLAGS_TF | X86_EFLAGS_RF);

	kvm_x86_ops->set_rflags(vcpu, rflags);

	/*

	 * Trigger an rflags update that will inject or remove the trace

	 * flags.

	 */

	kvm_set_rflags(vcpu, rflags);



	kvm_x86_ops->set_guest_debug(vcpu, dbg);