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Commit dab4b911 authored by Jan Kiszka's avatar Jan Kiszka Committed by Marcelo Tosatti
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KVM: x86: Extend KVM_SET_VCPU_EVENTS with selective updates 



User space may not want to overwrite asynchronously changing VCPU event
states on write-back. So allow to skip nmi.pending and sipi_vector by
setting corresponding bits in the flags field of kvm_vcpu_events.

[avi: advertise the bits in KVM_GET_VCPU_EVENTS]

Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 6e24a6ef

Documentation/kvm/api.txt

+9 −1
Original line number Diff line number Diff line
@@ -685,7 +685,7 @@ struct kvm_vcpu_events { 
		__u8 pad;

	} nmi;

	__u32 sipi_vector;

	__u32 flags;   /* must be zero */

	__u32 flags;

};



4.30 KVM_SET_VCPU_EVENTS
@@ -701,6 +701,14 @@ vcpu. 


See KVM_GET_VCPU_EVENTS for the data structure.



Fields that may be modified asynchronously by running VCPUs can be excluded

from the update. These fields are nmi.pending and sipi_vector. Keep the

corresponding bits in the flags field cleared to suppress overwriting the

current in-kernel state. The bits are:



KVM_VCPUEVENT_VALID_NMI_PENDING - transfer nmi.pending to the kernel

KVM_VCPUEVENT_VALID_SIPI_VECTOR - transfer sipi_vector





5. The kvm_run structure

arch/x86/include/asm/kvm.h

+4 −0
Original line number Diff line number Diff line
@@ -254,6 +254,10 @@ struct kvm_reinject_control { 
	__u8 reserved[31];

};



/* When set in flags, include corresponding fields on KVM_SET_VCPU_EVENTS */

#define KVM_VCPUEVENT_VALID_NMI_PENDING	0x00000001

#define KVM_VCPUEVENT_VALID_SIPI_VECTOR	0x00000002



/* for KVM_GET/SET_VCPU_EVENTS */

struct kvm_vcpu_events {

	struct {

arch/x86/kvm/x86.c

+8 −4
Original line number Diff line number Diff line
@@ -1913,7 +1913,8 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu, 


	events->sipi_vector = vcpu->arch.sipi_vector;



	events->flags = 0;

	events->flags = (KVM_VCPUEVENT_VALID_NMI_PENDING

			 | KVM_VCPUEVENT_VALID_SIPI_VECTOR);



	vcpu_put(vcpu);

}
@@ -1921,7 +1922,8 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu, 
static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,

					      struct kvm_vcpu_events *events)

{

	if (events->flags)

	if (events->flags & ~(KVM_VCPUEVENT_VALID_NMI_PENDING

			      | KVM_VCPUEVENT_VALID_SIPI_VECTOR))

		return -EINVAL;



	vcpu_load(vcpu);
@@ -1938,9 +1940,11 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu, 
		kvm_pic_clear_isr_ack(vcpu->kvm);



	vcpu->arch.nmi_injected = events->nmi.injected;

	if (events->flags & KVM_VCPUEVENT_VALID_NMI_PENDING)

		vcpu->arch.nmi_pending = events->nmi.pending;

	kvm_x86_ops->set_nmi_mask(vcpu, events->nmi.masked);



	if (events->flags & KVM_VCPUEVENT_VALID_SIPI_VECTOR)

		vcpu->arch.sipi_vector = events->sipi_vector;



	vcpu_put(vcpu);