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.
Signed-off-by: Jan Kiszka <jan.kis...@siemens.com> --- Documentation/kvm/api.txt | 10 +++++++++- arch/x86/include/asm/kvm.h | 4 ++++ arch/x86/kvm/x86.c | 9 ++++++--- 3 files changed, 19 insertions(+), 4 deletions(-) diff --git a/Documentation/kvm/api.txt b/Documentation/kvm/api.txt index e1a1141..ee07e3a 100644 --- a/Documentation/kvm/api.txt +++ b/Documentation/kvm/api.txt @@ -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. Set the +corresponding mask bits in the flags field to suppress overwriting their +current state: + +KVM_VCPUEVENT_MASK_NMI_PENDING - do not update nmi.pending +KVM_VCPUEVENT_MASK_SIPI_VECTOR - do not update sipi_vector + 5. The kvm_run structure diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h index 950df43..acf8585 100644 --- a/arch/x86/include/asm/kvm.h +++ b/arch/x86/include/asm/kvm.h @@ -254,6 +254,10 @@ struct kvm_reinject_control { __u8 reserved[31]; }; +/* When set in flags, skip corresponding fields on KVM_SET_VCPU_EVENTS */ +#define KVM_VCPUEVENT_MASK_NMI_PENDING 0x00000001 +#define KVM_VCPUEVENT_MASK_SIPI_VECTOR 0x00000002 + /* for KVM_GET/SET_VCPU_EVENTS */ struct kvm_vcpu_events { struct { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index dd15d7a..368843c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1953,7 +1953,8 @@ 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_MASK_NMI_PENDING | KVM_VCPUEVENT_MASK_SIPI_VECTOR)) return -EINVAL; vcpu_load(vcpu); @@ -1970,10 +1971,12 @@ 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_MASK_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_MASK_SIPI_VECTOR)) + vcpu->arch.sipi_vector = events->sipi_vector; vcpu_put(vcpu);
signature.asc
Description: OpenPGP digital signature