Commit a1efbe77 authored by Jan Kiszka's avatar Jan Kiszka Committed by Avi Kivity
Browse files

KVM: x86: Add support for saving&restoring debug registers 



So far user space was not able to save and restore debug registers for
migration or after reset. Plug this hole.

Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 48005f64

Documentation/kvm/api.txt

+31 −0
Original line number Diff line number Diff line
@@ -718,6 +718,37 @@ If KVM_CAP_INTR_SHADOW is available, KVM_VCPUEVENT_VALID_SHADOW can be set in 
the flags field to signal that interrupt.shadow contains a valid state and

shall be written into the VCPU.



4.32 KVM_GET_DEBUGREGS



Capability: KVM_CAP_DEBUGREGS

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_debugregs (out)

Returns: 0 on success, -1 on error



Reads debug registers from the vcpu.



struct kvm_debugregs {

	__u64 db[4];

	__u64 dr6;

	__u64 dr7;

	__u64 flags;

	__u64 reserved[9];

};



4.33 KVM_SET_DEBUGREGS



Capability: KVM_CAP_DEBUGREGS

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_debugregs (in)

Returns: 0 on success, -1 on error



Writes debug registers into the vcpu.



See KVM_GET_DEBUGREGS for the data structure. The flags field is unused

yet and must be cleared on entry.





5. The kvm_run structure

arch/x86/include/asm/kvm.h

+10 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#define __KVM_HAVE_PIT_STATE2

#define __KVM_HAVE_XEN_HVM

#define __KVM_HAVE_VCPU_EVENTS

#define __KVM_HAVE_DEBUGREGS



/* Architectural interrupt line count. */

#define KVM_NR_INTERRUPTS 256
@@ -289,4 +290,13 @@ struct kvm_vcpu_events { 
	__u32 reserved[10];

};



/* for KVM_GET/SET_DEBUGREGS */

struct kvm_debugregs {

	__u64 db[4];

	__u64 dr6;

	__u64 dr7;

	__u64 flags;

	__u64 reserved[9];

};



#endif /* _ASM_X86_KVM_H */

arch/x86/kvm/x86.c

+54 −0
Original line number Diff line number Diff line
@@ -1548,6 +1548,7 @@ int kvm_dev_ioctl_check_extension(long ext) 
	case KVM_CAP_HYPERV_VAPIC:

	case KVM_CAP_HYPERV_SPIN:

	case KVM_CAP_PCI_SEGMENT:

	case KVM_CAP_DEBUGREGS:

	case KVM_CAP_X86_ROBUST_SINGLESTEP:

		r = 1;

		break;
@@ -2165,6 +2166,36 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu, 
	return 0;

}



static void kvm_vcpu_ioctl_x86_get_debugregs(struct kvm_vcpu *vcpu,

					     struct kvm_debugregs *dbgregs)

{

	vcpu_load(vcpu);



	memcpy(dbgregs->db, vcpu->arch.db, sizeof(vcpu->arch.db));

	dbgregs->dr6 = vcpu->arch.dr6;

	dbgregs->dr7 = vcpu->arch.dr7;

	dbgregs->flags = 0;



	vcpu_put(vcpu);

}



static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu,

					    struct kvm_debugregs *dbgregs)

{

	if (dbgregs->flags)

		return -EINVAL;



	vcpu_load(vcpu);



	memcpy(vcpu->arch.db, dbgregs->db, sizeof(vcpu->arch.db));

	vcpu->arch.dr6 = dbgregs->dr6;

	vcpu->arch.dr7 = dbgregs->dr7;



	vcpu_put(vcpu);



	return 0;

}



long kvm_arch_vcpu_ioctl(struct file *filp,

			 unsigned int ioctl, unsigned long arg)

{
@@ -2343,6 +2374,29 @@ long kvm_arch_vcpu_ioctl(struct file *filp, 
		r = kvm_vcpu_ioctl_x86_set_vcpu_events(vcpu, &events);

		break;

	}

	case KVM_GET_DEBUGREGS: {

		struct kvm_debugregs dbgregs;



		kvm_vcpu_ioctl_x86_get_debugregs(vcpu, &dbgregs);



		r = -EFAULT;

		if (copy_to_user(argp, &dbgregs,

				 sizeof(struct kvm_debugregs)))

			break;

		r = 0;

		break;

	}

	case KVM_SET_DEBUGREGS: {

		struct kvm_debugregs dbgregs;



		r = -EFAULT;

		if (copy_from_user(&dbgregs, argp,

				   sizeof(struct kvm_debugregs)))

			break;



		r = kvm_vcpu_ioctl_x86_set_debugregs(vcpu, &dbgregs);

		break;

	}

	default:

		r = -EINVAL;

	}

include/linux/kvm.h

+6 −0
Original line number Diff line number Diff line
@@ -503,6 +503,9 @@ struct kvm_ioeventfd { 
#define KVM_CAP_PCI_SEGMENT 47

#define KVM_CAP_PPC_PAIRED_SINGLES 48

#define KVM_CAP_INTR_SHADOW 49

#ifdef __KVM_HAVE_DEBUGREGS

#define KVM_CAP_DEBUGREGS 50

#endif

#define KVM_CAP_X86_ROBUST_SINGLESTEP 51



#ifdef KVM_CAP_IRQ_ROUTING
@@ -690,6 +693,9 @@ struct kvm_clock_data { 
/* Available with KVM_CAP_VCPU_EVENTS */

#define KVM_GET_VCPU_EVENTS       _IOR(KVMIO,  0x9f, struct kvm_vcpu_events)

#define KVM_SET_VCPU_EVENTS       _IOW(KVMIO,  0xa0, struct kvm_vcpu_events)

/* Available with KVM_CAP_DEBUGREGS */

#define KVM_GET_DEBUGREGS         _IOR(KVMIO,  0xa1, struct kvm_debugregs)

#define KVM_SET_DEBUGREGS         _IOW(KVMIO,  0xa2, struct kvm_debugregs)



#define KVM_DEV_ASSIGN_ENABLE_IOMMU	(1 << 0)