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KVM: x86: Extend KVM_SET_VCPU_EVENTS with selective updates

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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: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Jan Kiszka 2009-12-06 18:24:15 +01:00 committed by Marcelo Tosatti
parent 6e24a6eff4
commit dab4b911a5
3 changed files with 21 additions and 5 deletions
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10
Documentation/kvm/api.txt
View file

@ -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

4
arch/x86/include/asm/kvm.h
View file

@ -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 {

12
arch/x86/kvm/x86.c
View file

@ -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);
@ -1938,10 +1940,12 @@ 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;
vcpu->arch.nmi_pending = events->nmi.pending;
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);
vcpu->arch.sipi_vector = events->sipi_vector;
if (events->flags & KVM_VCPUEVENT_VALID_SIPI_VECTOR)
vcpu->arch.sipi_vector = events->sipi_vector;
vcpu_put(vcpu);