[PATCH v4 09/13] KVM: arm64: Allow userspace to configure a vCPU's virtual offset
From: Oliver Upton <hidden>
Date: 2021-07-29 00:14:56
Also in:
kvm, kvmarm
Subsystem:
arm64 port (aarch64 architecture), documentation, kernel virtual machine (kvm), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Jonathan Corbet, Paolo Bonzini, Marc Zyngier, Oliver Upton, Linus Torvalds
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. Reviewed-by: Andrew Jones <redacted> Signed-off-by: Oliver Upton <redacted> --- 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; }
--
2.32.0.432.gabb21c7263-goog
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel