KVM: s390: add floating irq controller

This patch adds a floating irq controller as a kvm_device.
It will be necessary for migration of floating interrupts as well
as for hardening the reset code by allowing user space to explicitly
remove all pending floating interrupts.

Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

8 files changed, 312 insertions, 51 deletions

diff --git a/Documentation/virtual/kvm/devices/s390_flic.txt b/Documentation/virtual/kvm/devices/s390_flic.txt
new file mode 100644
index 000000000000..6b557953066a
--- /dev/null
+++ b/Documentation/virtual/kvm/devices/s390_flic.txt
@@ -0,0 +1,36 @@
+FLIC (floating interrupt controller)
+====================================
+
+FLIC handles floating (non per-cpu) interrupts, i.e. I/O, service and some
+machine check interruptions. All interrupts are stored in a per-vm list of
+pending interrupts. FLIC performs operations on this list.
+
+Only one FLIC instance may be instantiated.
+
+FLIC provides support to
+- add interrupts (KVM_DEV_FLIC_ENQUEUE)
+- inspect currently pending interrupts (KVM_FLIC_GET_ALL_IRQS)
+- purge all pending floating interrupts (KVM_DEV_FLIC_CLEAR_IRQS)
+
+Groups:
+  KVM_DEV_FLIC_ENQUEUE
+    Passes a buffer and length into the kernel which are then injected into
+    the list of pending interrupts.
+    attr->addr contains the pointer to the buffer and attr->attr contains
+    the length of the buffer.
+    The format of the data structure kvm_s390_irq as it is copied from userspace
+    is defined in usr/include/linux/kvm.h.
+
+  KVM_DEV_FLIC_GET_ALL_IRQS
+    Copies all floating interrupts into a buffer provided by userspace.
+    When the buffer is too small it returns -ENOMEM, which is the indication
+    for userspace to try again with a bigger buffer.
+    All interrupts remain pending, i.e. are not deleted from the list of
+    currently pending interrupts.
+    attr->addr contains the userspace address of the buffer into which all
+    interrupt data will be copied.
+    attr->attr contains the size of the buffer in bytes.
+
+  KVM_DEV_FLIC_CLEAR_IRQS
+    Simply deletes all elements from the list of currently pending floating
+    interrupts.  No interrupts are injected into the guest.
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 3ffc9646e742..59635b5c59a6 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -243,6 +243,7 @@ struct kvm_arch{
         struct sca_block *sca;
         debug_info_t *dbf;
         struct kvm_s390_float_interrupt float_int;
+        struct kvm_device *flic;
         struct gmap *gmap;
         int css_support;
 };
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index d25da598ec62..38d5f98552bb 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -16,6 +16,20 @@
 
 #define __KVM_S390
 
+/* Device control API: s390-specific devices */
+#define KVM_DEV_FLIC_GET_ALL_IRQS       1
+#define KVM_DEV_FLIC_ENQUEUE            2
+#define KVM_DEV_FLIC_CLEAR_IRQS         3
+/*
+ * We can have up to 4*64k pending subchannels + 8 adapter interrupts,
+ * as well as up  to ASYNC_PF_PER_VCPU*KVM_MAX_VCPUS pfault done interrupts.
+ * There are also sclp and machine checks. This gives us
+ * sizeof(kvm_s390_irq)*(4*65536+8+64*64+1+1) = 72 * 266250 = 19170000
+ * Lets round up to 8192 pages.
+ */
+
+#define KVM_S390_FLIC_MAX_BUFFER        0x2000000
+
 /* for KVM_GET_REGS and KVM_SET_REGS */
 struct kvm_regs {
         /* general purpose regs for s390 */
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 5f79d2d79ca7..a5f18babed4c 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -659,53 +659,86 @@ struct kvm_s390_interrupt_info *kvm_s390_get_io_int(struct kvm *kvm,
         return inti;
 }
 
-int kvm_s390_inject_vm(struct kvm *kvm,
-                       struct kvm_s390_interrupt *s390int)
+static void __inject_vm(struct kvm *kvm, struct kvm_s390_interrupt_info *inti)
 {
         struct kvm_s390_local_interrupt *li;
         struct kvm_s390_float_interrupt *fi;
-        struct kvm_s390_interrupt_info *inti, *iter;
+        struct kvm_s390_interrupt_info *iter;
         int sigcpu;
 
+        mutex_lock(&kvm->lock);
+        fi = &kvm->arch.float_int;
+        spin_lock(&fi->lock);
+        if (!is_ioint(inti->type)) {
+                list_add_tail(&inti->list, &fi->list);
+        } else {
+                u64 isc_bits = int_word_to_isc_bits(inti->io.io_int_word);
+
+                /* Keep I/O interrupts sorted in isc order. */
+                list_for_each_entry(iter, &fi->list, list) {
+                        if (!is_ioint(iter->type))
+                                continue;
+                        if (int_word_to_isc_bits(iter->io.io_int_word)
+                            <= isc_bits)
+                                continue;
+                        break;
+                }
+                list_add_tail(&inti->list, &iter->list);
+        }
+        atomic_set(&fi->active, 1);
+        sigcpu = find_first_bit(fi->idle_mask, KVM_MAX_VCPUS);
+        if (sigcpu == KVM_MAX_VCPUS) {
+                do {
+                        sigcpu = fi->next_rr_cpu++;
+                        if (sigcpu == KVM_MAX_VCPUS)
+                                sigcpu = fi->next_rr_cpu = 0;
+                } while (fi->local_int[sigcpu] == NULL);
+        }
+        li = fi->local_int[sigcpu];
+        spin_lock_bh(&li->lock);
+        atomic_set_mask(CPUSTAT_EXT_INT, li->cpuflags);
+        if (waitqueue_active(li->wq))
+                wake_up_interruptible(li->wq);
+        spin_unlock_bh(&li->lock);
+        spin_unlock(&fi->lock);
+        mutex_unlock(&kvm->lock);
+}
+
+int kvm_s390_inject_vm(struct kvm *kvm,
+                       struct kvm_s390_interrupt *s390int)
+{
+        struct kvm_s390_interrupt_info *inti;
+
         inti = kzalloc(sizeof(*inti), GFP_KERNEL);
         if (!inti)
                 return -ENOMEM;
 
-        switch (s390int->type) {
+        inti->type = s390int->type;
+        switch (inti->type) {
         case KVM_S390_INT_VIRTIO:
                 VM_EVENT(kvm, 5, "inject: virtio parm:%x,parm64:%llx",
                          s390int->parm, s390int->parm64);
-                inti->type = s390int->type;
                 inti->ext.ext_params = s390int->parm;
                 inti->ext.ext_params2 = s390int->parm64;
                 break;
         case KVM_S390_INT_SERVICE:
                 VM_EVENT(kvm, 5, "inject: sclp parm:%x", s390int->parm);
-                inti->type = s390int->type;
                 inti->ext.ext_params = s390int->parm;
                 break;
-        case KVM_S390_PROGRAM_INT:
-        case KVM_S390_SIGP_STOP:
-        case KVM_S390_INT_EXTERNAL_CALL:
-        case KVM_S390_INT_EMERGENCY:
-                kfree(inti);
-                return -EINVAL;
         case KVM_S390_MCHK:
                 VM_EVENT(kvm, 5, "inject: machine check parm64:%llx",
                          s390int->parm64);
-                inti->type = s390int->type;
                 inti->mchk.cr14 = s390int->parm; /* upper bits are not used */
                 inti->mchk.mcic = s390int->parm64;
                 break;
         case KVM_S390_INT_IO_MIN...KVM_S390_INT_IO_MAX:
-                if (s390int->type & IOINT_AI_MASK)
+                if (inti->type & IOINT_AI_MASK)
                         VM_EVENT(kvm, 5, "%s", "inject: I/O (AI)");
                 else
                         VM_EVENT(kvm, 5, "inject: I/O css %x ss %x schid %04x",
                                  s390int->type & IOINT_CSSID_MASK,
                                  s390int->type & IOINT_SSID_MASK,
                                  s390int->type & IOINT_SCHID_MASK);
-                inti->type = s390int->type;
                 inti->io.subchannel_id = s390int->parm >> 16;
                 inti->io.subchannel_nr = s390int->parm & 0x0000ffffu;
                 inti->io.io_int_parm = s390int->parm64 >> 32;
@@ -718,42 +751,7 @@ int kvm_s390_inject_vm(struct kvm *kvm,
         trace_kvm_s390_inject_vm(s390int->type, s390int->parm, s390int->parm64,
                                  2);
 
-        mutex_lock(&kvm->lock);
-        fi = &kvm->arch.float_int;
-        spin_lock(&fi->lock);
-        if (!is_ioint(inti->type))
-                list_add_tail(&inti->list, &fi->list);
-        else {
-                u64 isc_bits = int_word_to_isc_bits(inti->io.io_int_word);
-
-                /* Keep I/O interrupts sorted in isc order. */
-                list_for_each_entry(iter, &fi->list, list) {
-                        if (!is_ioint(iter->type))
-                                continue;
-                        if (int_word_to_isc_bits(iter->io.io_int_word)
-                            <= isc_bits)
-                                continue;
-                        break;
-                }
-                list_add_tail(&inti->list, &iter->list);
-        }
-        atomic_set(&fi->active, 1);
-        sigcpu = find_first_bit(fi->idle_mask, KVM_MAX_VCPUS);
-        if (sigcpu == KVM_MAX_VCPUS) {
-                do {
-                        sigcpu = fi->next_rr_cpu++;
-                        if (sigcpu == KVM_MAX_VCPUS)
-                                sigcpu = fi->next_rr_cpu = 0;
-                } while (fi->local_int[sigcpu] == NULL);
-        }
-        li = fi->local_int[sigcpu];
-        spin_lock_bh(&li->lock);
-        atomic_set_mask(CPUSTAT_EXT_INT, li->cpuflags);
-        if (waitqueue_active(li->wq))
-                wake_up_interruptible(li->wq);
-        spin_unlock_bh(&li->lock);
-        spin_unlock(&fi->lock);
-        mutex_unlock(&kvm->lock);
+        __inject_vm(kvm, inti);
         return 0;
 }
 
@@ -841,3 +839,207 @@ int kvm_s390_inject_vcpu(struct kvm_vcpu *vcpu,
         mutex_unlock(&vcpu->kvm->lock);
         return 0;
 }
+
+static void clear_floating_interrupts(struct kvm *kvm)
+{
+        struct kvm_s390_float_interrupt *fi;
+        struct kvm_s390_interrupt_info  *n, *inti = NULL;
+
+        mutex_lock(&kvm->lock);
+        fi = &kvm->arch.float_int;
+        spin_lock(&fi->lock);
+        list_for_each_entry_safe(inti, n, &fi->list, list) {
+                list_del(&inti->list);
+                kfree(inti);
+        }
+        atomic_set(&fi->active, 0);
+        spin_unlock(&fi->lock);
+        mutex_unlock(&kvm->lock);
+}
+
+static inline int copy_irq_to_user(struct kvm_s390_interrupt_info *inti,
+                                   u8 *addr)
+{
+        struct kvm_s390_irq __user *uptr = (struct kvm_s390_irq __user *) addr;
+        struct kvm_s390_irq irq = {0};
+
+        irq.type = inti->type;
+        switch (inti->type) {
+        case KVM_S390_INT_VIRTIO:
+        case KVM_S390_INT_SERVICE:
+                irq.u.ext = inti->ext;
+                break;
+        case KVM_S390_INT_IO_MIN...KVM_S390_INT_IO_MAX:
+                irq.u.io = inti->io;
+                break;
+        case KVM_S390_MCHK:
+                irq.u.mchk = inti->mchk;
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        if (copy_to_user(uptr, &irq, sizeof(irq)))
+                return -EFAULT;
+
+        return 0;
+}
+
+static int get_all_floating_irqs(struct kvm *kvm, __u8 *buf, __u64 len)
+{
+        struct kvm_s390_interrupt_info *inti;
+        struct kvm_s390_float_interrupt *fi;
+        int ret = 0;
+        int n = 0;
+
+        mutex_lock(&kvm->lock);
+        fi = &kvm->arch.float_int;
+        spin_lock(&fi->lock);
+
+        list_for_each_entry(inti, &fi->list, list) {
+                if (len < sizeof(struct kvm_s390_irq)) {
+                        /* signal userspace to try again */
+                        ret = -ENOMEM;
+                        break;
+                }
+                ret = copy_irq_to_user(inti, buf);
+                if (ret)
+                        break;
+                buf += sizeof(struct kvm_s390_irq);
+                len -= sizeof(struct kvm_s390_irq);
+                n++;
+        }
+
+        spin_unlock(&fi->lock);
+        mutex_unlock(&kvm->lock);
+
+        return ret < 0 ? ret : n;
+}
+
+static int flic_get_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
+{
+        int r;
+
+        switch (attr->group) {
+        case KVM_DEV_FLIC_GET_ALL_IRQS:
+                r = get_all_floating_irqs(dev->kvm, (u8 *) attr->addr,
+                                          attr->attr);
+                break;
+        default:
+                r = -EINVAL;
+        }
+
+        return r;
+}
+
+static inline int copy_irq_from_user(struct kvm_s390_interrupt_info *inti,
+                                     u64 addr)
+{
+        struct kvm_s390_irq __user *uptr = (struct kvm_s390_irq __user *) addr;
+        void *target = NULL;
+        void __user *source;
+        u64 size;
+
+        if (get_user(inti->type, (u64 __user *)addr))
+                return -EFAULT;
+
+        switch (inti->type) {
+        case KVM_S390_INT_VIRTIO:
+        case KVM_S390_INT_SERVICE:
+                target = (void *) &inti->ext;
+                source = &uptr->u.ext;
+                size = sizeof(inti->ext);
+                break;
+        case KVM_S390_INT_IO_MIN...KVM_S390_INT_IO_MAX:
+                target = (void *) &inti->io;
+                source = &uptr->u.io;
+                size = sizeof(inti->io);
+                break;
+        case KVM_S390_MCHK:
+                target = (void *) &inti->mchk;
+                source = &uptr->u.mchk;
+                size = sizeof(inti->mchk);
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        if (copy_from_user(target, source, size))
+                return -EFAULT;
+
+        return 0;
+}
+
+static int enqueue_floating_irq(struct kvm_device *dev,
+                                struct kvm_device_attr *attr)
+{
+        struct kvm_s390_interrupt_info *inti = NULL;
+        int r = 0;
+        int len = attr->attr;
+
+        if (len % sizeof(struct kvm_s390_irq) != 0)
+                return -EINVAL;
+        else if (len > KVM_S390_FLIC_MAX_BUFFER)
+                return -EINVAL;
+
+        while (len >= sizeof(struct kvm_s390_irq)) {
+                inti = kzalloc(sizeof(*inti), GFP_KERNEL);
+                if (!inti)
+                        return -ENOMEM;
+
+                r = copy_irq_from_user(inti, attr->addr);
+                if (r) {
+                        kfree(inti);
+                        return r;
+                }
+                __inject_vm(dev->kvm, inti);
+                len -= sizeof(struct kvm_s390_irq);
+                attr->addr += sizeof(struct kvm_s390_irq);
+        }
+
+        return r;
+}
+
+static int flic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
+{
+        int r = 0;
+
+        switch (attr->group) {
+        case KVM_DEV_FLIC_ENQUEUE:
+                r = enqueue_floating_irq(dev, attr);
+                break;
+        case KVM_DEV_FLIC_CLEAR_IRQS:
+                r = 0;
+                clear_floating_interrupts(dev->kvm);
+                break;
+        default:
+                r = -EINVAL;
+        }
+
+        return r;
+}
+
+static int flic_create(struct kvm_device *dev, u32 type)
+{
+        if (!dev)
+                return -EINVAL;
+        if (dev->kvm->arch.flic)
+                return -EINVAL;
+        dev->kvm->arch.flic = dev;
+        return 0;
+}
+
+static void flic_destroy(struct kvm_device *dev)
+{
+        dev->kvm->arch.flic = NULL;
+        kfree(dev);
+}
+
+/* s390 floating irq controller (flic) */
+struct kvm_device_ops kvm_flic_ops = {
+        .name = "kvm-flic",
+        .get_attr = flic_get_attr,
+        .set_attr = flic_set_attr,
+        .create = flic_create,
+        .destroy = flic_destroy,
+};
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index e0676f390d57..782420f3c4d5 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -157,6 +157,7 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_ENABLE_CAP:
         case KVM_CAP_S390_CSS_SUPPORT:
         case KVM_CAP_IOEVENTFD:
+        case KVM_CAP_DEVICE_CTRL:
                 r = 1;
                 break;
         case KVM_CAP_NR_VCPUS:
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index b8e9a43e501a..c0102ef2de48 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1064,6 +1064,7 @@ extern struct kvm_device_ops kvm_mpic_ops;
 extern struct kvm_device_ops kvm_xics_ops;
 extern struct kvm_device_ops kvm_vfio_ops;
 extern struct kvm_device_ops kvm_arm_vgic_v2_ops;
+extern struct kvm_device_ops kvm_flic_ops;
 
 #ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
 
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 86faf47ae494..19f717b15297 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -918,6 +918,7 @@ struct kvm_device_attr {
 #define   KVM_DEV_VFIO_GROUP_ADD                        1
 #define   KVM_DEV_VFIO_GROUP_DEL                        2
 #define KVM_DEV_TYPE_ARM_VGIC_V2        5
+#define KVM_DEV_TYPE_FLIC               6
 
 /*
  * ioctls for VM fds
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 03a0381b1cb7..a9e999a48e43 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2284,6 +2284,11 @@ static int kvm_ioctl_create_device(struct kvm *kvm,
                 ops = &kvm_arm_vgic_v2_ops;
                 break;
 #endif
+#ifdef CONFIG_S390
+        case KVM_DEV_TYPE_FLIC:
+                ops = &kvm_flic_ops;
+                break;
+#endif
         default:
                 return -ENODEV;
         }