KVM: s390: irq routing for adapter interrupts.

Introduce a new interrupt class for s390 adapter interrupts and enable
irqfds for s390.

This is depending on a new s390 specific vm capability, KVM_CAP_S390_IRQCHIP,
that needs to be enabled by userspace.

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

5 files changed, 163 insertions, 1 deletions

diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
index c8bacbcd2e5b..10d529ac9821 100644
--- a/arch/s390/kvm/Kconfig
+++ b/arch/s390/kvm/Kconfig
@@ -25,6 +25,8 @@ config KVM
         select HAVE_KVM_EVENTFD
         select KVM_ASYNC_PF
         select KVM_ASYNC_PF_SYNC
+        select HAVE_KVM_IRQCHIP
+        select HAVE_KVM_IRQ_ROUTING
         ---help---
           Support hosting paravirtualized guest machines using the SIE
           virtualization capability on the mainframe. This should work
diff --git a/arch/s390/kvm/Makefile b/arch/s390/kvm/Makefile
index a47d2c355f68..d3adb37e93a4 100644
--- a/arch/s390/kvm/Makefile
+++ b/arch/s390/kvm/Makefile
@@ -7,7 +7,7 @@
 # as published by the Free Software Foundation.
 
 KVM := ../../../virt/kvm
-common-objs = $(KVM)/kvm_main.o $(KVM)/eventfd.o  $(KVM)/async_pf.o
+common-objs = $(KVM)/kvm_main.o $(KVM)/eventfd.o  $(KVM)/async_pf.o $(KVM)/irqchip.o
 
 ccflags-y := -Ivirt/kvm -Iarch/s390/kvm
 
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 7ecef5a18e25..2e2814eceb85 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -13,6 +13,7 @@
 #include <linux/interrupt.h>
 #include <linux/kvm_host.h>
 #include <linux/hrtimer.h>
+#include <linux/mmu_context.h>
 #include <linux/signal.h>
 #include <linux/slab.h>
 #include <asm/asm-offsets.h>
@@ -1284,3 +1285,123 @@ struct kvm_device_ops kvm_flic_ops = {
         .create = flic_create,
         .destroy = flic_destroy,
 };
+
+static unsigned long get_ind_bit(__u64 addr, unsigned long bit_nr, bool swap)
+{
+        unsigned long bit;
+
+        bit = bit_nr + (addr % PAGE_SIZE) * 8;
+
+        return swap ? (bit ^ (BITS_PER_LONG - 1)) : bit;
+}
+
+static struct s390_map_info *get_map_info(struct s390_io_adapter *adapter,
+                                          u64 addr)
+{
+        struct s390_map_info *map;
+
+        if (!adapter)
+                return NULL;
+
+        list_for_each_entry(map, &adapter->maps, list) {
+                if (map->guest_addr == addr)
+                        return map;
+        }
+        return NULL;
+}
+
+static int adapter_indicators_set(struct kvm *kvm,
+                                  struct s390_io_adapter *adapter,
+                                  struct kvm_s390_adapter_int *adapter_int)
+{
+        unsigned long bit;
+        int summary_set, idx;
+        struct s390_map_info *info;
+        void *map;
+
+        info = get_map_info(adapter, adapter_int->ind_addr);
+        if (!info)
+                return -1;
+        map = page_address(info->page);
+        bit = get_ind_bit(info->addr, adapter_int->ind_offset, adapter->swap);
+        set_bit(bit, map);
+        idx = srcu_read_lock(&kvm->srcu);
+        mark_page_dirty(kvm, info->guest_addr >> PAGE_SHIFT);
+        set_page_dirty_lock(info->page);
+        info = get_map_info(adapter, adapter_int->summary_addr);
+        if (!info) {
+                srcu_read_unlock(&kvm->srcu, idx);
+                return -1;
+        }
+        map = page_address(info->page);
+        bit = get_ind_bit(info->addr, adapter_int->summary_offset,
+                          adapter->swap);
+        summary_set = test_and_set_bit(bit, map);
+        mark_page_dirty(kvm, info->guest_addr >> PAGE_SHIFT);
+        set_page_dirty_lock(info->page);
+        srcu_read_unlock(&kvm->srcu, idx);
+        return summary_set ? 0 : 1;
+}
+
+/*
+ * < 0 - not injected due to error
+ * = 0 - coalesced, summary indicator already active
+ * > 0 - injected interrupt
+ */
+static int set_adapter_int(struct kvm_kernel_irq_routing_entry *e,
+                           struct kvm *kvm, int irq_source_id, int level,
+                           bool line_status)
+{
+        int ret;
+        struct s390_io_adapter *adapter;
+
+        /* We're only interested in the 0->1 transition. */
+        if (!level)
+                return 0;
+        adapter = get_io_adapter(kvm, e->adapter.adapter_id);
+        if (!adapter)
+                return -1;
+        down_read(&adapter->maps_lock);
+        ret = adapter_indicators_set(kvm, adapter, &e->adapter);
+        up_read(&adapter->maps_lock);
+        if ((ret > 0) && !adapter->masked) {
+                struct kvm_s390_interrupt s390int = {
+                        .type = KVM_S390_INT_IO(1, 0, 0, 0),
+                        .parm = 0,
+                        .parm64 = (adapter->isc << 27) | 0x80000000,
+                };
+                ret = kvm_s390_inject_vm(kvm, &s390int);
+                if (ret == 0)
+                        ret = 1;
+        }
+        return ret;
+}
+
+int kvm_set_routing_entry(struct kvm_irq_routing_table *rt,
+                          struct kvm_kernel_irq_routing_entry *e,
+                          const struct kvm_irq_routing_entry *ue)
+{
+        int ret;
+
+        switch (ue->type) {
+        case KVM_IRQ_ROUTING_S390_ADAPTER:
+                e->set = set_adapter_int;
+                e->adapter.summary_addr = ue->u.adapter.summary_addr;
+                e->adapter.ind_addr = ue->u.adapter.ind_addr;
+                e->adapter.summary_offset = ue->u.adapter.summary_offset;
+                e->adapter.ind_offset = ue->u.adapter.ind_offset;
+                e->adapter.adapter_id = ue->u.adapter.adapter_id;
+                ret = 0;
+                break;
+        default:
+                ret = -EINVAL;
+        }
+
+        return ret;
+}
+
+int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e, struct kvm *kvm,
+                int irq_source_id, int level, bool line_status)
+{
+        return -EINVAL;
+}
diff --git a/arch/s390/kvm/irq.h b/arch/s390/kvm/irq.h
new file mode 100644
index 000000000000..d98e4159643d
--- /dev/null
+++ b/arch/s390/kvm/irq.h
@@ -0,0 +1,22 @@
+/*
+ * s390 irqchip routines
+ *
+ * Copyright IBM Corp. 2014
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2 only)
+ * as published by the Free Software Foundation.
+ *
+ *    Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
+ */
+#ifndef __KVM_IRQ_H
+#define __KVM_IRQ_H
+
+#include <linux/kvm_host.h>
+
+static inline int irqchip_in_kernel(struct kvm *kvm)
+{
+        return 1;
+}
+
+#endif
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 2e6fbb0b4f68..ce5b659ec531 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -196,6 +196,10 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
                 return -EINVAL;
 
         switch (cap->cap) {
+        case KVM_CAP_S390_IRQCHIP:
+                kvm->arch.use_irqchip = 1;
+                r = 0;
+                break;
         default:
                 r = -EINVAL;
                 break;
@@ -228,6 +232,18 @@ long kvm_arch_vm_ioctl(struct file *filp,
                 r = kvm_vm_ioctl_enable_cap(kvm, &cap);
                 break;
         }
+        case KVM_CREATE_IRQCHIP: {
+                struct kvm_irq_routing_entry routing;
+
+                r = -EINVAL;
+                if (kvm->arch.use_irqchip) {
+                        /* Set up dummy routing. */
+                        memset(&routing, 0, sizeof(routing));
+                        kvm_set_irq_routing(kvm, &routing, 0, 0);
+                        r = 0;
+                }
+                break;
+        }
         default:
                 r = -ENOTTY;
         }
@@ -284,6 +300,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
         }
 
         kvm->arch.css_support = 0;
+        kvm->arch.use_irqchip = 0;
 
         return 0;
 out_nogmap: