[PATCH v4 8/8] arm/arm64: KVM: vgic: make number of irqs a configurable attribute

Marc Zyngier
2014-09-11T11:09:40Z

In order to make the number of interrupts configurable, use the new
fancy device management API to add KVM_DEV_ARM_VGIC_GRP_NR_IRQS as
a VGIC configurable attribute.

Userspace can now specify the exact size of the GIC (by increments
of 32 interrupts).

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
Documentation/virtual/kvm/devices/arm-vgic.txt | 10 +++++++
arch/arm/include/uapi/asm/kvm.h | 1 +
arch/arm64/include/uapi/asm/kvm.h | 1 +
virt/kvm/arm/vgic.c | 37 ++++++++++++++++++++++++++
4 files changed, 49 insertions(+)

diff --git a/Documentation/virtual/kvm/devices/arm-vgic.txt b/Documentation/virtual/kvm/devices/arm-vgic.txt
index 7f4e91b..df8b0c7 100644
--- a/Documentation/virtual/kvm/devices/arm-vgic.txt
+++ b/Documentation/virtual/kvm/devices/arm-vgic.txt
@@ -71,3 +71,13 @@ Groups:
Errors:
-ENODEV: Getting or setting this register is not yet supported
-EBUSY: One or more VCPUs are running
+
+ KVM_DEV_ARM_VGIC_GRP_NR_IRQS
+ Attributes:
+ A value describing the number of interrupts (SGI, PPI and SPI) for
+ this GIC instance, ranging from 64 to 1024, in increments of 32.
+
+ Errors:
+ -EINVAL: Value set is out of the expected range
+ -EBUSY: Value has already be set, or GIC has already been initialized
+ with default values.
diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h
index e6ebdd3..8b51c1a 100644
--- a/arch/arm/include/uapi/asm/kvm.h
+++ b/arch/arm/include/uapi/asm/kvm.h
@@ -173,6 +173,7 @@ struct kvm_arch_memory_slot {
#define KVM_DEV_ARM_VGIC_CPUID_MASK (0xffULL << KVM_DEV_ARM_VGIC_CPUID_SHIFT)
#define KVM_DEV_ARM_VGIC_OFFSET_SHIFT 0
#define KVM_DEV_ARM_VGIC_OFFSET_MASK (0xffffffffULL << KVM_DEV_ARM_VGIC_OFFSET_SHIFT)
+#define KVM_DEV_ARM_VGIC_GRP_NR_IRQS 3

/* KVM_IRQ_LINE irq field index values */
#define KVM_ARM_IRQ_TYPE_SHIFT 24
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index e633ff8..b5cd6ed 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -159,6 +159,7 @@ struct kvm_arch_memory_slot {
#define KVM_DEV_ARM_VGIC_CPUID_MASK (0xffULL << KVM_DEV_ARM_VGIC_CPUID_SHIFT)
#define KVM_DEV_ARM_VGIC_OFFSET_SHIFT 0
#define KVM_DEV_ARM_VGIC_OFFSET_MASK (0xffffffffULL << KVM_DEV_ARM_VGIC_OFFSET_SHIFT)
+#define KVM_DEV_ARM_VGIC_GRP_NR_IRQS 3

/* KVM_IRQ_LINE irq field index values */
#define KVM_ARM_IRQ_TYPE_SHIFT 24
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 9180823..744388d 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -2331,6 +2331,36 @@ static int vgic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)

return vgic_attr_regs_access(dev, attr, &reg, true);
}
+ case KVM_DEV_ARM_VGIC_GRP_NR_IRQS: {
+ u32 __user *uaddr = (u32 __user *)(long)attr->addr;
+ u32 val;
+ int ret = 0;
+
+ if (get_user(val, uaddr))
+ return -EFAULT;
+
+ /*
+ * We require:
+ * - at least 32 SPIs on top of the 16 SGIs and 16 PPIs
+ * - at most 1024 interrupts
+ * - a multiple of 32 interrupts
+ */
+ if (val < (VGIC_NR_PRIVATE_IRQS + 32) ||
+ val > VGIC_MAX_IRQS ||
+ (val & 31))
+ return -EINVAL;
+
+ mutex_lock(&dev->kvm->lock);
+
+ if (vgic_initialized(dev->kvm) || dev->kvm->arch.vgic.nr_irqs)
+ ret = -EBUSY;
+ else
+ dev->kvm->arch.vgic.nr_irqs = val;
+
+ mutex_unlock(&dev->kvm->lock);
+
+ return ret;
+ }

}

@@ -2367,6 +2397,11 @@ static int vgic_get_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
r = put_user(reg, uaddr);
break;
}
+ case KVM_DEV_ARM_VGIC_GRP_NR_IRQS: {
+ u32 __user *uaddr = (u32 __user *)(long)attr->addr;
+ r = put_user(dev->kvm->arch.vgic.nr_irqs, uaddr);
+ break;
+ }

}

@@ -2403,6 +2438,8 @@ static int vgic_has_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
case KVM_DEV_ARM_VGIC_GRP_CPU_REGS:
offset = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
return vgic_has_attr_regs(vgic_cpu_ranges, offset);
+ case KVM_DEV_ARM_VGIC_GRP_NR_IRQS:
+ return 0;
}
return -ENXIO;
}
--
2.0.4