KVM: arm-vgic: Add vgic reg access from dev attr

Add infrastructure to handle distributor and cpu interface register
accesses through the KVM_{GET/SET}_DEVICE_ATTR interface by adding the
KVM_DEV_ARM_VGIC_GRP_DIST_REGS and KVM_DEV_ARM_VGIC_GRP_CPU_REGS groups
and defining the semantics of the attr field to be the MMIO offset as
specified in the GICv2 specs.

Missing register accesses or other changes in individual register access
functions to support save/restore of the VGIC state is added in
subsequent patches.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

1 files changed, 178 insertions, 0 deletions

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index e2596f618281..88599b585362 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -589,6 +589,20 @@ static bool handle_mmio_sgi_reg(struct kvm_vcpu *vcpu,
         return false;
 }
 
+static bool handle_mmio_sgi_clear(struct kvm_vcpu *vcpu,
+                                  struct kvm_exit_mmio *mmio,
+                                  phys_addr_t offset)
+{
+        return false;
+}
+
+static bool handle_mmio_sgi_set(struct kvm_vcpu *vcpu,
+                                struct kvm_exit_mmio *mmio,
+                                phys_addr_t offset)
+{
+        return false;
+}
+
 /*
  * I would have liked to use the kvm_bus_io_*() API instead, but it
  * cannot cope with banked registers (only the VM pointer is passed
@@ -663,6 +677,16 @@ static const struct mmio_range vgic_dist_ranges[] = {
                 .len            = 4,
                 .handle_mmio    = handle_mmio_sgi_reg,
         },
+        {
+                .base           = GIC_DIST_SGI_PENDING_CLEAR,
+                .len            = VGIC_NR_SGIS,
+                .handle_mmio    = handle_mmio_sgi_clear,
+        },
+        {
+                .base           = GIC_DIST_SGI_PENDING_SET,
+                .len            = VGIC_NR_SGIS,
+                .handle_mmio    = handle_mmio_sgi_set,
+        },
         {}
 };
 
@@ -1557,6 +1581,114 @@ int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write)
         return r;
 }
 
+static bool handle_cpu_mmio_misc(struct kvm_vcpu *vcpu,
+                                 struct kvm_exit_mmio *mmio, phys_addr_t offset)
+{
+        return true;
+}
+
+static const struct mmio_range vgic_cpu_ranges[] = {
+        {
+                .base           = GIC_CPU_CTRL,
+                .len            = 12,
+                .handle_mmio    = handle_cpu_mmio_misc,
+        },
+        {
+                .base           = GIC_CPU_ALIAS_BINPOINT,
+                .len            = 4,
+                .handle_mmio    = handle_cpu_mmio_misc,
+        },
+        {
+                .base           = GIC_CPU_ACTIVEPRIO,
+                .len            = 16,
+                .handle_mmio    = handle_cpu_mmio_misc,
+        },
+        {
+                .base           = GIC_CPU_IDENT,
+                .len            = 4,
+                .handle_mmio    = handle_cpu_mmio_misc,
+        },
+};
+
+static int vgic_attr_regs_access(struct kvm_device *dev,
+                                 struct kvm_device_attr *attr,
+                                 u32 *reg, bool is_write)
+{
+        const struct mmio_range *r = NULL, *ranges;
+        phys_addr_t offset;
+        int ret, cpuid, c;
+        struct kvm_vcpu *vcpu, *tmp_vcpu;
+        struct vgic_dist *vgic;
+        struct kvm_exit_mmio mmio;
+
+        offset = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
+        cpuid = (attr->attr & KVM_DEV_ARM_VGIC_CPUID_MASK) >>
+                KVM_DEV_ARM_VGIC_CPUID_SHIFT;
+
+        mutex_lock(&dev->kvm->lock);
+
+        if (cpuid >= atomic_read(&dev->kvm->online_vcpus)) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        vcpu = kvm_get_vcpu(dev->kvm, cpuid);
+        vgic = &dev->kvm->arch.vgic;
+
+        mmio.len = 4;
+        mmio.is_write = is_write;
+        if (is_write)
+                mmio_data_write(&mmio, ~0, *reg);
+        switch (attr->group) {
+        case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
+                mmio.phys_addr = vgic->vgic_dist_base + offset;
+                ranges = vgic_dist_ranges;
+                break;
+        case KVM_DEV_ARM_VGIC_GRP_CPU_REGS:
+                mmio.phys_addr = vgic->vgic_cpu_base + offset;
+                ranges = vgic_cpu_ranges;
+                break;
+        default:
+                BUG();
+        }
+        r = find_matching_range(ranges, &mmio, offset);
+
+        if (unlikely(!r || !r->handle_mmio)) {
+                ret = -ENXIO;
+                goto out;
+        }
+
+
+        spin_lock(&vgic->lock);
+
+        /*
+         * Ensure that no other VCPU is running by checking the vcpu->cpu
+         * field.  If no other VPCUs are running we can safely access the VGIC
+         * state, because even if another VPU is run after this point, that
+         * VCPU will not touch the vgic state, because it will block on
+         * getting the vgic->lock in kvm_vgic_sync_hwstate().
+         */
+        kvm_for_each_vcpu(c, tmp_vcpu, dev->kvm) {
+                if (unlikely(tmp_vcpu->cpu != -1)) {
+                        ret = -EBUSY;
+                        goto out_vgic_unlock;
+                }
+        }
+
+        offset -= r->base;
+        r->handle_mmio(vcpu, &mmio, offset);
+
+        if (!is_write)
+                *reg = mmio_data_read(&mmio, ~0);
+
+        ret = 0;
+out_vgic_unlock:
+        spin_unlock(&vgic->lock);
+out:
+        mutex_unlock(&dev->kvm->lock);
+        return ret;
+}
+
 static int vgic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
 {
         int r;
@@ -1573,6 +1705,18 @@ static int vgic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
                 r = kvm_vgic_addr(dev->kvm, type, &addr, true);
                 return (r == -ENODEV) ? -ENXIO : r;
         }
+
+        case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
+        case KVM_DEV_ARM_VGIC_GRP_CPU_REGS: {
+                u32 __user *uaddr = (u32 __user *)(long)attr->addr;
+                u32 reg;
+
+                if (get_user(reg, uaddr))
+                        return -EFAULT;
+
+                return vgic_attr_regs_access(dev, attr, &reg, true);
+        }
+
         }
 
         return -ENXIO;
@@ -1594,14 +1738,42 @@ static int vgic_get_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
 
                 if (copy_to_user(uaddr, &addr, sizeof(addr)))
                         return -EFAULT;
+                break;
+        }
+
+        case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
+        case KVM_DEV_ARM_VGIC_GRP_CPU_REGS: {
+                u32 __user *uaddr = (u32 __user *)(long)attr->addr;
+                u32 reg = 0;
+
+                r = vgic_attr_regs_access(dev, attr, &reg, false);
+                if (r)
+                        return r;
+                r = put_user(reg, uaddr);
+                break;
         }
+
         }
 
         return r;
 }
 
+static int vgic_has_attr_regs(const struct mmio_range *ranges,
+                              phys_addr_t offset)
+{
+        struct kvm_exit_mmio dev_attr_mmio;
+
+        dev_attr_mmio.len = 4;
+        if (find_matching_range(ranges, &dev_attr_mmio, offset))
+                return 0;
+        else
+                return -ENXIO;
+}
+
 static int vgic_has_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
 {
+        phys_addr_t offset;
+
         switch (attr->group) {
         case KVM_DEV_ARM_VGIC_GRP_ADDR:
                 switch (attr->attr) {
@@ -1610,6 +1782,12 @@ static int vgic_has_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
                         return 0;
                 }
                 break;
+        case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
+                offset = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
+                return vgic_has_attr_regs(vgic_dist_ranges, offset);
+        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);
         }
         return -ENXIO;
 }