Commit b0305c1e authored by David Woodhouse's avatar David Woodhouse Committed by Paolo Bonzini
Browse files

KVM: x86/xen: Add KVM_XEN_INVALID_GPA and KVM_XEN_INVALID_GFN to uapi 



These are (uint64_t)-1 magic values are a userspace ABI, allowing the
shared info pages and other enlightenments to be disabled. This isn't
a Xen ABI because Xen doesn't let the guest turn these off except with
the full SHUTDOWN_soft_reset mechanism. Under KVM, the userspace VMM is
expected to handle soft reset, and tear down the kernel parts of the
enlightenments accordingly.

Suggested-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20221226120320.1125390-5-dwmw2@infradead.org>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 1c14faa5

arch/x86/kvm/xen.c

+7 −7
Original line number Diff line number Diff line
@@ -41,7 +41,7 @@ static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn) 
	int ret = 0;

	int idx = srcu_read_lock(&kvm->srcu);



	if (gfn == GPA_INVALID) {

	if (gfn == KVM_XEN_INVALID_GFN) {

		kvm_gpc_deactivate(gpc);

		goto out;

	}
@@ -659,7 +659,7 @@ int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data) 
		if (kvm->arch.xen.shinfo_cache.active)

			data->u.shared_info.gfn = gpa_to_gfn(kvm->arch.xen.shinfo_cache.gpa);

		else

			data->u.shared_info.gfn = GPA_INVALID;

			data->u.shared_info.gfn = KVM_XEN_INVALID_GFN;

		r = 0;

		break;
@@ -705,7 +705,7 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) 
		BUILD_BUG_ON(offsetof(struct vcpu_info, time) !=

			     offsetof(struct compat_vcpu_info, time));



		if (data->u.gpa == GPA_INVALID) {

		if (data->u.gpa == KVM_XEN_INVALID_GPA) {

			kvm_gpc_deactivate(&vcpu->arch.xen.vcpu_info_cache);

			r = 0;

			break;
@@ -719,7 +719,7 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) 
		break;



	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO:

		if (data->u.gpa == GPA_INVALID) {

		if (data->u.gpa == KVM_XEN_INVALID_GPA) {

			kvm_gpc_deactivate(&vcpu->arch.xen.vcpu_time_info_cache);

			r = 0;

			break;
@@ -739,7 +739,7 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) 
			r = -EOPNOTSUPP;

			break;

		}

		if (data->u.gpa == GPA_INVALID) {

		if (data->u.gpa == KVM_XEN_INVALID_GPA) {

			r = 0;

		deactivate_out:

			kvm_gpc_deactivate(&vcpu->arch.xen.runstate_cache);
@@ -937,7 +937,7 @@ int kvm_xen_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) 
		if (vcpu->arch.xen.vcpu_info_cache.active)

			data->u.gpa = vcpu->arch.xen.vcpu_info_cache.gpa;

		else

			data->u.gpa = GPA_INVALID;

			data->u.gpa = KVM_XEN_INVALID_GPA;

		r = 0;

		break;
@@ -945,7 +945,7 @@ int kvm_xen_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) 
		if (vcpu->arch.xen.vcpu_time_info_cache.active)

			data->u.gpa = vcpu->arch.xen.vcpu_time_info_cache.gpa;

		else

			data->u.gpa = GPA_INVALID;

			data->u.gpa = KVM_XEN_INVALID_GPA;

		r = 0;

		break;

include/uapi/linux/kvm.h

+3 −0
Original line number Diff line number Diff line
@@ -1767,6 +1767,7 @@ struct kvm_xen_hvm_attr { 
		__u8 runstate_update_flag;

		struct {

			__u64 gfn;

#define KVM_XEN_INVALID_GFN ((__u64)-1)

		} shared_info;

		struct {

			__u32 send_port;
@@ -1798,6 +1799,7 @@ struct kvm_xen_hvm_attr { 
	} u;

};





/* Available with KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO */

#define KVM_XEN_ATTR_TYPE_LONG_MODE		0x0

#define KVM_XEN_ATTR_TYPE_SHARED_INFO		0x1
@@ -1823,6 +1825,7 @@ struct kvm_xen_vcpu_attr { 
	__u16 pad[3];

	union {

		__u64 gpa;

#define KVM_XEN_INVALID_GPA ((__u64)-1)

		__u64 pad[8];

		struct {

			__u64 state;