KVM: Adds support for in-kernel mmio handlers

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

2 files changed, 142 insertions, 12 deletions

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index b08272bce213..31846b1c162f 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -265,6 +265,65 @@ struct kvm_stat {
         u32 efer_reload;
 };
 
+struct kvm_io_device {
+        void (*read)(struct kvm_io_device *this,
+                     gpa_t addr,
+                     int len,
+                     void *val);
+        void (*write)(struct kvm_io_device *this,
+                      gpa_t addr,
+                      int len,
+                      const void *val);
+        int (*in_range)(struct kvm_io_device *this, gpa_t addr);
+        void (*destructor)(struct kvm_io_device *this);
+
+        void             *private;
+};
+
+static inline void kvm_iodevice_read(struct kvm_io_device *dev,
+                                     gpa_t addr,
+                                     int len,
+                                     void *val)
+{
+        dev->read(dev, addr, len, val);
+}
+
+static inline void kvm_iodevice_write(struct kvm_io_device *dev,
+                                      gpa_t addr,
+                                      int len,
+                                      const void *val)
+{
+        dev->write(dev, addr, len, val);
+}
+
+static inline int kvm_iodevice_inrange(struct kvm_io_device *dev, gpa_t addr)
+{
+        return dev->in_range(dev, addr);
+}
+
+static inline void kvm_iodevice_destructor(struct kvm_io_device *dev)
+{
+        dev->destructor(dev);
+}
+
+/*
+ * It would be nice to use something smarter than a linear search, TBD...
+ * Thankfully we dont expect many devices to register (famous last words :),
+ * so until then it will suffice.  At least its abstracted so we can change
+ * in one place.
+ */
+struct kvm_io_bus {
+        int                   dev_count;
+#define NR_IOBUS_DEVS 6
+        struct kvm_io_device *devs[NR_IOBUS_DEVS];
+};
+
+void kvm_io_bus_init(struct kvm_io_bus *bus);
+void kvm_io_bus_destroy(struct kvm_io_bus *bus);
+struct kvm_io_device *kvm_io_bus_find_dev(struct kvm_io_bus *bus, gpa_t addr);
+void kvm_io_bus_register_dev(struct kvm_io_bus *bus,
+                             struct kvm_io_device *dev);
+
 struct kvm_vcpu {
         struct kvm *kvm;
         union {
@@ -393,6 +452,7 @@ struct kvm {
         unsigned long rmap_overflow;
         struct list_head vm_list;
         struct file *filp;
+        struct kvm_io_bus mmio_bus;
 };
 
 struct descriptor_table {
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 633c2eded08d..e157e282fcff 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -366,6 +366,7 @@ static struct kvm *kvm_create_vm(void)
         spin_lock(&kvm_lock);
         list_add(&kvm->vm_list, &vm_list);
         spin_unlock(&kvm_lock);
+        kvm_io_bus_init(&kvm->mmio_bus);
         for (i = 0; i < KVM_MAX_VCPUS; ++i) {
                 struct kvm_vcpu *vcpu = &kvm->vcpus[i];
 
@@ -474,6 +475,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
         spin_lock(&kvm_lock);
         list_del(&kvm->vm_list);
         spin_unlock(&kvm_lock);
+        kvm_io_bus_destroy(&kvm->mmio_bus);
         kvm_free_vcpus(kvm);
         kvm_free_physmem(kvm);
         kfree(kvm);
@@ -1097,12 +1099,25 @@ static int emulator_write_std(unsigned long addr,
         return X86EMUL_UNHANDLEABLE;
 }
 
+static struct kvm_io_device *vcpu_find_mmio_dev(struct kvm_vcpu *vcpu,
+                                                gpa_t addr)
+{
+        /*
+         * Note that its important to have this wrapper function because
+         * in the very near future we will be checking for MMIOs against
+         * the LAPIC as well as the general MMIO bus
+         */
+        return kvm_io_bus_find_dev(&vcpu->kvm->mmio_bus, addr);
+}
+
 static int emulator_read_emulated(unsigned long addr,
                                   void *val,
                                   unsigned int bytes,
                                   struct x86_emulate_ctxt *ctxt)
 {
-        struct kvm_vcpu *vcpu = ctxt->vcpu;
+        struct kvm_vcpu      *vcpu = ctxt->vcpu;
+        struct kvm_io_device *mmio_dev;
+        gpa_t                 gpa;
 
         if (vcpu->mmio_read_completed) {
                 memcpy(val, vcpu->mmio_data, bytes);
@@ -1111,18 +1126,26 @@ static int emulator_read_emulated(unsigned long addr,
         } else if (emulator_read_std(addr, val, bytes, ctxt)
                    == X86EMUL_CONTINUE)
                 return X86EMUL_CONTINUE;
-        else {
-                gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
 
-                if (gpa == UNMAPPED_GVA)
-                        return X86EMUL_PROPAGATE_FAULT;
-                vcpu->mmio_needed = 1;
-                vcpu->mmio_phys_addr = gpa;
-                vcpu->mmio_size = bytes;
-                vcpu->mmio_is_write = 0;
+        gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
+        if (gpa == UNMAPPED_GVA)
+                return X86EMUL_PROPAGATE_FAULT;
 
-                return X86EMUL_UNHANDLEABLE;
+        /*
+         * Is this MMIO handled locally?
+         */
+        mmio_dev = vcpu_find_mmio_dev(vcpu, gpa);
+        if (mmio_dev) {
+                kvm_iodevice_read(mmio_dev, gpa, bytes, val);
+                return X86EMUL_CONTINUE;
         }
+
+        vcpu->mmio_needed = 1;
+        vcpu->mmio_phys_addr = gpa;
+        vcpu->mmio_size = bytes;
+        vcpu->mmio_is_write = 0;
+
+        return X86EMUL_UNHANDLEABLE;
 }
 
 static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
@@ -1150,8 +1173,9 @@ static int emulator_write_emulated(unsigned long addr,
                                    unsigned int bytes,
                                    struct x86_emulate_ctxt *ctxt)
 {
-        struct kvm_vcpu *vcpu = ctxt->vcpu;
-        gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
+        struct kvm_vcpu      *vcpu = ctxt->vcpu;
+        struct kvm_io_device *mmio_dev;
+        gpa_t                 gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
 
         if (gpa == UNMAPPED_GVA) {
                 kvm_arch_ops->inject_page_fault(vcpu, addr, 2);
@@ -1161,6 +1185,15 @@ static int emulator_write_emulated(unsigned long addr,
         if (emulator_write_phys(vcpu, gpa, val, bytes))
                 return X86EMUL_CONTINUE;
 
+        /*
+         * Is this MMIO handled locally?
+         */
+        mmio_dev = vcpu_find_mmio_dev(vcpu, gpa);
+        if (mmio_dev) {
+                kvm_iodevice_write(mmio_dev, gpa, bytes, val);
+                return X86EMUL_CONTINUE;
+        }
+
         vcpu->mmio_needed = 1;
         vcpu->mmio_phys_addr = gpa;
         vcpu->mmio_size = bytes;
@@ -3031,6 +3064,43 @@ static int kvm_cpu_hotplug(struct notifier_block *notifier, unsigned long val,
         return NOTIFY_OK;
 }
 
+void kvm_io_bus_init(struct kvm_io_bus *bus)
+{
+        memset(bus, 0, sizeof(*bus));
+}
+
+void kvm_io_bus_destroy(struct kvm_io_bus *bus)
+{
+        int i;
+
+        for (i = 0; i < bus->dev_count; i++) {
+                struct kvm_io_device *pos = bus->devs[i];
+
+                kvm_iodevice_destructor(pos);
+        }
+}
+
+struct kvm_io_device *kvm_io_bus_find_dev(struct kvm_io_bus *bus, gpa_t addr)
+{
+        int i;
+
+        for (i = 0; i < bus->dev_count; i++) {
+                struct kvm_io_device *pos = bus->devs[i];
+
+                if (pos->in_range(pos, addr))
+                        return pos;
+        }
+
+        return NULL;
+}
+
+void kvm_io_bus_register_dev(struct kvm_io_bus *bus, struct kvm_io_device *dev)
+{
+        BUG_ON(bus->dev_count > (NR_IOBUS_DEVS-1));
+
+        bus->devs[bus->dev_count++] = dev;
+}
+
 static struct notifier_block kvm_cpu_notifier = {
         .notifier_call = kvm_cpu_hotplug,
         .priority = 20, /* must be > scheduler priority */