On Mon, Jul 19, 2021 at 06:49:45PM +0000, Oliver Upton wrote: > Add a new vCPU attribute that allows userspace to directly manipulate > the virtual counter-timer offset. Exposing such an interface allows for > the precise migration of guest virtual counter-timers, as it is an > indepotent interface. > > Uphold the existing behavior of writes to CNTVOFF_EL2 for this new > interface, wherein a write to a single vCPU is broadcasted to all vCPUs > within a VM. > > Signed-off-by: Oliver Upton <[email protected]> > --- > Documentation/virt/kvm/devices/vcpu.rst | 22 ++++++++ > arch/arm64/include/uapi/asm/kvm.h | 1 + > arch/arm64/kvm/arch_timer.c | 68 ++++++++++++++++++++++++- > 3 files changed, 89 insertions(+), 2 deletions(-) > > diff --git a/Documentation/virt/kvm/devices/vcpu.rst > b/Documentation/virt/kvm/devices/vcpu.rst > index b46d5f742e69..7b57cba3416a 100644 > --- a/Documentation/virt/kvm/devices/vcpu.rst > +++ b/Documentation/virt/kvm/devices/vcpu.rst > @@ -139,6 +139,28 @@ configured values on other VCPUs. Userspace should > configure the interrupt > numbers on at least one VCPU after creating all VCPUs and before running any > VCPUs. > > +2.2. ATTRIBUTE: KVM_ARM_VCPU_TIMER_OFFSET_VTIMER > +------------------------------------------------ > + > +:Parameters: Pointer to a 64-bit unsigned counter-timer offset. > + > +Returns: > + > + ======= ====================================== > + -EFAULT Error reading/writing the provided > + parameter address > + -ENXIO Attribute not supported > + ======= ====================================== > + > +Specifies the guest's virtual counter-timer offset from the host's > +virtual counter. The guest's virtual counter is then derived by > +the following equation: > + > + guest_cntvct = host_cntvct - KVM_ARM_VCPU_TIMER_OFFSET_VTIMER > + > +KVM does not allow the use of varying offset values for different vCPUs; > +the last written offset value will be broadcasted to all vCPUs in a VM. > + > 3. GROUP: KVM_ARM_VCPU_PVTIME_CTRL > ================================== > > diff --git a/arch/arm64/include/uapi/asm/kvm.h > b/arch/arm64/include/uapi/asm/kvm.h > index b3edde68bc3e..008d0518d2b1 100644 > --- a/arch/arm64/include/uapi/asm/kvm.h > +++ b/arch/arm64/include/uapi/asm/kvm.h > @@ -365,6 +365,7 @@ struct kvm_arm_copy_mte_tags { > #define KVM_ARM_VCPU_TIMER_CTRL 1 > #define KVM_ARM_VCPU_TIMER_IRQ_VTIMER 0 > #define KVM_ARM_VCPU_TIMER_IRQ_PTIMER 1 > +#define KVM_ARM_VCPU_TIMER_OFFSET_VTIMER 2 > #define KVM_ARM_VCPU_PVTIME_CTRL 2 > #define KVM_ARM_VCPU_PVTIME_IPA 0 > > diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c > index 3df67c127489..d2b1b13af658 100644 > --- a/arch/arm64/kvm/arch_timer.c > +++ b/arch/arm64/kvm/arch_timer.c > @@ -1305,7 +1305,7 @@ static void set_timer_irqs(struct kvm *kvm, int > vtimer_irq, int ptimer_irq) > } > } > > -int kvm_arm_timer_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr > *attr) > +int kvm_arm_timer_set_attr_irq(struct kvm_vcpu *vcpu, struct kvm_device_attr > *attr) > { > int __user *uaddr = (int __user *)(long)attr->addr; > struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); > @@ -1338,7 +1338,39 @@ int kvm_arm_timer_set_attr(struct kvm_vcpu *vcpu, > struct kvm_device_attr *attr) > return 0; > } > > -int kvm_arm_timer_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr > *attr) > +int kvm_arm_timer_set_attr_offset(struct kvm_vcpu *vcpu, struct > kvm_device_attr *attr) > +{ > + u64 __user *uaddr = (u64 __user *)(long)attr->addr; > + u64 offset; > + > + if (get_user(offset, uaddr)) > + return -EFAULT; > + > + switch (attr->attr) { > + case KVM_ARM_VCPU_TIMER_OFFSET_VTIMER: > + update_vtimer_cntvoff(vcpu, offset); > + break; > + default: > + return -ENXIO; > + } > + > + return 0; > +} > + > +int kvm_arm_timer_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr > *attr) > +{ > + switch (attr->attr) { > + case KVM_ARM_VCPU_TIMER_IRQ_VTIMER: > + case KVM_ARM_VCPU_TIMER_IRQ_PTIMER: > + return kvm_arm_timer_set_attr_irq(vcpu, attr); > + case KVM_ARM_VCPU_TIMER_OFFSET_VTIMER: > + return kvm_arm_timer_set_attr_offset(vcpu, attr); > + } > + > + return -ENXIO; > +} > + > +int kvm_arm_timer_get_attr_irq(struct kvm_vcpu *vcpu, struct kvm_device_attr > *attr) > { > int __user *uaddr = (int __user *)(long)attr->addr; > struct arch_timer_context *timer; > @@ -1359,11 +1391,43 @@ int kvm_arm_timer_get_attr(struct kvm_vcpu *vcpu, > struct kvm_device_attr *attr) > return put_user(irq, uaddr); > } > > +int kvm_arm_timer_get_attr_offset(struct kvm_vcpu *vcpu, struct > kvm_device_attr *attr) > +{ > + u64 __user *uaddr = (u64 __user *)(long)attr->addr; > + struct arch_timer_context *timer; > + u64 offset; > + > + switch (attr->attr) { > + case KVM_ARM_VCPU_TIMER_OFFSET_VTIMER: > + timer = vcpu_vtimer(vcpu); > + break; > + default: > + return -ENXIO; > + } > + > + offset = timer_get_offset(timer); > + return put_user(offset, uaddr); > +} > + > +int kvm_arm_timer_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr > *attr) > +{ > + switch (attr->attr) { > + case KVM_ARM_VCPU_TIMER_IRQ_VTIMER: > + case KVM_ARM_VCPU_TIMER_IRQ_PTIMER: > + return kvm_arm_timer_get_attr_irq(vcpu, attr); > + case KVM_ARM_VCPU_TIMER_OFFSET_VTIMER: > + return kvm_arm_timer_get_attr_offset(vcpu, attr); > + } > + > + return -ENXIO; > +} > + > int kvm_arm_timer_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr > *attr) > { > switch (attr->attr) { > case KVM_ARM_VCPU_TIMER_IRQ_VTIMER: > case KVM_ARM_VCPU_TIMER_IRQ_PTIMER: > + case KVM_ARM_VCPU_TIMER_OFFSET_VTIMER: > return 0; > } > > -- > 2.32.0.402.g57bb445576-goog > > _______________________________________________ > kvmarm mailing list > [email protected] > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm >
Reviewed-by: Andrew Jones <[email protected]> _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
