[PATCH 40/55] KVM: arm64: vgic-its: Implement ITS command queue command handlers

[marc.zyngier@arm.com (Marc Zyngier)]

From: Andre Przywara <andre.przywara@arm.com>

The connection between a device, an event ID, the LPI number and the
associated CPU is stored in in-memory tables in a GICv3, but their
format is not specified by the spec. Instead software uses a command
queue in a ring buffer to let an ITS implementation use its own
format.
Implement handlers for the various ITS commands and let them store
the requested relation into our own data structures. Those data
structures are protected by the its_lock mutex.
Our internal ring buffer read and write pointers are protected by the
its_cmd mutex, so that only one VCPU per ITS can handle commands at
any given time.
Error handling is very basic at the moment, as we don't have a good
way of communicating errors to the guest (usually an SError).
The INT command handler is missing from this patch, as we gain the
capability of actually injecting MSIs into the guest only later on.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 virt/kvm/arm/vgic/vgic-its.c | 661 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 660 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 6f43b3b..1408c88 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -33,6 +33,67 @@
 #include "vgic.h"
 #include "vgic-mmio.h"
 
+/*
+ * Creates a new (reference to a) struct vgic_irq for a given LPI.
+ * If this LPI is already mapped on another ITS, we increase its refcount
+ * and return a pointer to the existing structure.
+ * If this is a "new" LPI, we allocate and initialize a new struct vgic_irq.
+ * This function returns a pointer to the _unlocked_ structure.
+ */
+static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid)
+{
+	struct vgic_dist *dist = &kvm->arch.vgic;
+	struct vgic_irq *irq = vgic_get_irq(kvm, NULL, intid), *oldirq;
+
+	/* In this case there is no put, since we keep the reference. */
+	if (irq)
+		return irq;
+
+	irq = kzalloc(sizeof(struct vgic_irq), GFP_KERNEL);
+	if (!irq)
+		return NULL;
+
+	INIT_LIST_HEAD(&irq->lpi_list);
+	INIT_LIST_HEAD(&irq->ap_list);
+	spin_lock_init(&irq->irq_lock);
+
+	irq->config = VGIC_CONFIG_EDGE;
+	kref_init(&irq->refcount);
+	irq->intid = intid;
+
+	spin_lock(&dist->lpi_list_lock);
+
+	/*
+	 * There could be a race with another vgic_add_lpi(), so we need to
+	 * check that we don't add a second list entry with the same LPI.
+	 */
+	list_for_each_entry(oldirq, &dist->lpi_list_head, lpi_list) {
+		if (oldirq->intid != intid)
+			continue;
+
+		/* Someone was faster with adding this LPI, lets use that. */
+		kfree(irq);
+		irq = oldirq;
+
+		/*
+		 * This increases the refcount, the caller is expected to
+		 * call vgic_put_irq() on the returned pointer once it's
+		 * finished with the IRQ.
+		 */
+		kref_get(&irq->refcount);
+
+		goto out_unlock;
+	}
+
+	list_add_tail(&irq->lpi_list, &dist->lpi_list_head);
+	dist->lpi_list_count++;
+
+out_unlock:
+	spin_unlock(&dist->lpi_list_lock);
+
+	return irq;
+}
+
 struct its_device {
 	struct list_head dev_list;
 
@@ -63,15 +124,74 @@ struct its_itte {
 };
 
 /*
+ * Find and returns a device in the device table for an ITS.
+ * Must be called with the its_lock mutex held.
+ */
+static struct its_device *find_its_device(struct vgic_its *its, u32 device_id)
+{
+	struct its_device *device;
+
+	list_for_each_entry(device, &its->device_list, dev_list)
+		if (device_id == device->device_id)
+			return device;
+
+	return NULL;
+}
+
+/*
+ * Find and returns an interrupt translation table entry (ITTE) for a given
+ * Device ID/Event ID pair on an ITS.
+ * Must be called with the its_lock mutex held.
+ */
+static struct its_itte *find_itte(struct vgic_its *its, u32 device_id,
+				  u32 event_id)
+{
+	struct its_device *device;
+	struct its_itte *itte;
+
+	device = find_its_device(its, device_id);
+	if (device == NULL)
+		return NULL;
+
+	list_for_each_entry(itte, &device->itt_head, itte_list)
+		if (itte->event_id == event_id)
+			return itte;
+
+	return NULL;
+}
+
+/* To be used as an iterator this macro misses the enclosing parentheses */
+#define for_each_lpi_its(dev, itte, its) \
+	list_for_each_entry(dev, &(its)->device_list, dev_list) \
+		list_for_each_entry(itte, &(dev)->itt_head, itte_list)
+
+/*
  * We only implement 48 bits of PA at the moment, although the ITS
  * supports more. Let's be restrictive here.
  */
+#define BASER_ADDRESS(x)	((x) & GENMASK_ULL(47, 16))
 #define CBASER_ADDRESS(x)	((x) & GENMASK_ULL(47, 12))
 #define PENDBASER_ADDRESS(x)	((x) & GENMASK_ULL(47, 16))
 #define PROPBASER_ADDRESS(x)	((x) & GENMASK_ULL(47, 12))
 
 #define GIC_LPI_OFFSET 8192
 
+/*
+ * Finds and returns a collection in the ITS collection table.
+ * Must be called with the its_lock mutex held.
+ */
+static struct its_collection *find_collection(struct vgic_its *its, int coll_id)
+{
+	struct its_collection *collection;
+
+	list_for_each_entry(collection, &its->collection_list, coll_list) {
+		if (coll_id == collection->collection_id)
+			return collection;
+	}
+
+	return NULL;
+}
+
 #define LPI_PROP_ENABLE_BIT(p)	((p) & LPI_PROP_ENABLED)
 #define LPI_PROP_PRIORITY(p)	((p) & 0xfc)
 
@@ -145,6 +265,51 @@ static int vgic_copy_lpi_list(struct kvm *kvm, u32 **intid_ptr)
 }
 
 /*
+ * Promotes the ITS view of affinity of an ITTE (which redistributor this LPI
+ * is targeting) to the VGIC's view, which deals with target VCPUs.
+ * Needs to be called whenever either the collection for a LPIs has
+ * changed or the collection itself got retargeted.
+ */
+static void update_affinity_itte(struct kvm *kvm, struct its_itte *itte)
+{
+	struct kvm_vcpu *vcpu;
+
+	if (!its_is_collection_mapped(itte->collection))
+		return;
+
+	vcpu = kvm_get_vcpu(kvm, itte->collection->target_addr);
+
+	spin_lock(&itte->irq->irq_lock);
+	itte->irq->target_vcpu = vcpu;
+	spin_unlock(&itte->irq->irq_lock);
+}
+
+/*
+ * Updates the target VCPU for every LPI targeting this collection.
+ * Must be called with the its_lock mutex held.
+ */
+static void update_affinity_collection(struct kvm *kvm, struct vgic_its *its,
+				       struct its_collection *coll)
+{
+	struct its_device *device;
+	struct its_itte *itte;
+
+	for_each_lpi_its(device, itte, its) {
+		if (!itte->collection || coll != itte->collection)
+			continue;
+
+		update_affinity_itte(kvm, itte);
+	}
+}
+
+static u32 max_lpis_propbaser(u64 propbaser)
+{
+	int nr_idbits = (propbaser & 0x1f) + 1;
+
+	return 1U << min(nr_idbits, INTERRUPT_ID_BITS_ITS);
+}
+
+/*
  * Scan the whole LPI pending table and sync the pending bit in there
  * with our own data structures. This relies on the LPI being
  * mapped before.
@@ -283,10 +448,504 @@ static void its_free_itte(struct kvm *kvm, struct its_itte *itte)
 	kfree(itte);
 }
 
+static u64 its_cmd_mask_field(u64 *its_cmd, int word, int shift, int size)
+{
+	return (le64_to_cpu(its_cmd[word]) >> shift) & (BIT_ULL(size) - 1);
+}
+
+#define its_cmd_get_command(cmd)	its_cmd_mask_field(cmd, 0,  0,  8)
+#define its_cmd_get_deviceid(cmd)	its_cmd_mask_field(cmd, 0, 32, 32)
+#define its_cmd_get_id(cmd)		its_cmd_mask_field(cmd, 1,  0, 32)
+#define its_cmd_get_physical_id(cmd)	its_cmd_mask_field(cmd, 1, 32, 32)
+#define its_cmd_get_collection(cmd)	its_cmd_mask_field(cmd, 2,  0, 16)
+#define its_cmd_get_target_addr(cmd)	its_cmd_mask_field(cmd, 2, 16, 32)
+#define its_cmd_get_validbit(cmd)	its_cmd_mask_field(cmd, 2, 63,  1)
+
+/*
+ * The DISCARD command frees an Interrupt Translation Table Entry (ITTE).
+ * Must be called with the its_lock mutex held.
+ */
+static int vgic_its_cmd_handle_discard(struct kvm *kvm, struct vgic_its *its,
+				       u64 *its_cmd)
+{
+	u32 device_id = its_cmd_get_deviceid(its_cmd);
+	u32 event_id = its_cmd_get_id(its_cmd);
+	struct its_itte *itte;
+
+
+	itte = find_itte(its, device_id, event_id);
+	if (itte && itte->collection) {
+		/*
+		 * Though the spec talks about removing the pending state, we
+		 * don't bother here since we clear the ITTE anyway and the
+		 * pending state is a property of the ITTE struct.
+		 */
+		its_free_itte(kvm, itte);
+		return 0;
+	}
+
+	return E_ITS_DISCARD_UNMAPPED_INTERRUPT;
+}
+
+/*
+ * The MOVI command moves an ITTE to a different collection.
+ * Must be called with the its_lock mutex held.
+ */
+static int vgic_its_cmd_handle_movi(struct kvm *kvm, struct vgic_its *its,
+				    u64 *its_cmd)
+{
+	u32 device_id = its_cmd_get_deviceid(its_cmd);
+	u32 event_id = its_cmd_get_id(its_cmd);
+	u32 coll_id = its_cmd_get_collection(its_cmd);
+	struct kvm_vcpu *vcpu;
+	struct its_itte *itte;
+	struct its_collection *collection;
+
+	itte = find_itte(its, device_id, event_id);
+	if (!itte)
+		return E_ITS_MOVI_UNMAPPED_INTERRUPT;
+
+	if (!its_is_collection_mapped(itte->collection))
+		return E_ITS_MOVI_UNMAPPED_COLLECTION;
+
+	collection = find_collection(its, coll_id);
+	if (!its_is_collection_mapped(collection))
+		return E_ITS_MOVI_UNMAPPED_COLLECTION;
+
+	itte->collection = collection;
+	vcpu = kvm_get_vcpu(kvm, collection->target_addr);
+
+	spin_lock(&itte->irq->irq_lock);
+	itte->irq->target_vcpu = vcpu;
+	spin_unlock(&itte->irq->irq_lock);
+
+	return 0;
+}
+
+static void vgic_its_init_collection(struct vgic_its *its,
+				     struct its_collection *collection,
+				     u32 coll_id)
+{
+	collection->collection_id = coll_id;
+	collection->target_addr = COLLECTION_NOT_MAPPED;
+
+	list_add_tail(&collection->coll_list, &its->collection_list);
+}
+
+/*
+ * The MAPTI and MAPI commands map LPIs to ITTEs.
+ * Must be called with its_lock mutex held.
+ */
+static int vgic_its_cmd_handle_mapi(struct kvm *kvm, struct vgic_its *its,
+				    u64 *its_cmd, u8 subcmd)
+{
+	u32 device_id = its_cmd_get_deviceid(its_cmd);
+	u32 event_id = its_cmd_get_id(its_cmd);
+	u32 coll_id = its_cmd_get_collection(its_cmd);
+	struct its_itte *itte;
+	struct its_device *device;
+	struct its_collection *collection, *new_coll = NULL;
+	int lpi_nr;
+
+	device = find_its_device(its, device_id);
+	if (!device)
+		return E_ITS_MAPTI_UNMAPPED_DEVICE;
+
+	collection = find_collection(its, coll_id);
+	if (!collection) {
+		new_coll = kzalloc(sizeof(struct its_collection), GFP_KERNEL);
+		if (!new_coll)
+			return -ENOMEM;
+	}
+
+	if (subcmd == GITS_CMD_MAPTI)
+		lpi_nr = its_cmd_get_physical_id(its_cmd);
+	else
+		lpi_nr = event_id;
+	if (lpi_nr < GIC_LPI_OFFSET ||
+	    lpi_nr >= max_lpis_propbaser(kvm->arch.vgic.propbaser)) {
+		kfree(new_coll);
+		return E_ITS_MAPTI_PHYSICALID_OOR;
+	}
+
+	itte = find_itte(its, device_id, event_id);
+	if (!itte) {
+		itte = kzalloc(sizeof(struct its_itte), GFP_KERNEL);
+		if (!itte) {
+			kfree(new_coll);
+			return -ENOMEM;
+		}
+
+		itte->event_id	= event_id;
+		list_add_tail(&itte->itte_list, &device->itt_head);
+	}
+
+	if (!collection) {
+		collection = new_coll;
+		vgic_its_init_collection(its, collection, coll_id);
+	}
+
+	itte->collection = collection;
+	itte->lpi = lpi_nr;
+	itte->irq = vgic_add_lpi(kvm, lpi_nr);
+	update_affinity_itte(kvm, itte);
+
+	/*
+	 * We "cache" the configuration table entries in out struct vgic_irq's.
+	 * However we only have those structs for mapped IRQs, so we read in
+	 * the respective config data from memory here upon mapping the LPI.
+	 */
+	update_lpi_config(kvm, itte->irq, NULL);
+
+	return 0;
+}
+
+/* Requires the its_lock to be held. */
+static void vgic_its_unmap_device(struct kvm *kvm, struct its_device *device)
+{
+	struct its_itte *itte, *temp;
+
+	/*
+	 * The spec says that unmapping a device with still valid
+	 * ITTEs associated is UNPREDICTABLE. We remove all ITTEs,
+	 * since we cannot leave the memory unreferenced.
+	 */
+	list_for_each_entry_safe(itte, temp, &device->itt_head, itte_list)
+		its_free_itte(kvm, itte);
+
+	list_del(&device->dev_list);
+	kfree(device);
+}
+
+/*
+ * Check whether a device ID can be stored into the guest device tables.
+ * For a direct table this is pretty easy, but gets a bit nasty for
+ * indirect tables. We check whether the resulting guest physical address
+ * is actually valid (covered by a memslot and guest accessbible).
+ * For this we have to read the respective first level entry.
+ */
+static bool vgic_its_check_device_id(struct kvm *kvm, struct vgic_its *its,
+				     int device_id)
+{
+	u64 r = its->baser_device_table;
+	int nr_entries = GITS_BASER_NR_PAGES(r) * SZ_64K;
+	int index;
+	u64 indirect_ptr;
+	gfn_t gfn;
+
+
+	if (!(r & GITS_BASER_INDIRECT))
+		return device_id < (nr_entries / GITS_BASER_ENTRY_SIZE(r));
+
+	/* calculate and check the index into the 1st level */
+	index = device_id / (SZ_64K / GITS_BASER_ENTRY_SIZE(r));
+	if (index >= (nr_entries / sizeof(u64)))
+		return false;
+
+	/* Each 1st level entry is represented by a 64-bit value. */
+	if (!kvm_read_guest(kvm,
+			    BASER_ADDRESS(r) + index * sizeof(indirect_ptr),
+			    &indirect_ptr, sizeof(indirect_ptr)))
+		return false;
+
+	/* check the valid bit of the first level entry */
+	if (!(indirect_ptr & BIT_ULL(63)))
+		return false;
+
+	/*
+	 * Mask the guest physical address and calculate the frame number.
+	 * Any address beyond our supported 48 bits of PA will be caught
+	 * by the actual check in the final step.
+	 */
+	gfn = (indirect_ptr & GENMASK_ULL(51, 16)) >> PAGE_SHIFT;
+
+	return kvm_is_visible_gfn(kvm, gfn);
+}
+
+/*
+ * MAPD maps or unmaps a device ID to Interrupt Translation Tables (ITTs).
+ * Must be called with the its_lock mutex held.
+ */
+static int vgic_its_cmd_handle_mapd(struct kvm *kvm, struct vgic_its *its,
+				    u64 *its_cmd)
+{
+	u32 device_id = its_cmd_get_deviceid(its_cmd);
+	bool valid = its_cmd_get_validbit(its_cmd);
+	struct its_device *device;
+
+	if (!vgic_its_check_device_id(kvm, its, device_id))
+		return E_ITS_MAPD_DEVICE_OOR;
+
+	device = find_its_device(its, device_id);
+
+	/*
+	 * The spec says that calling MAPD on an already mapped device
+	 * invalidates all cached data for this device. We implement this
+	 * by removing the mapping and re-establishing it.
+	 */
+	if (device)
+		vgic_its_unmap_device(kvm, device);
+
+	/*
+	 * The spec does not say whether unmapping a not-mapped device
+	 * is an error, so we are done in any case.
+	 */
+	if (!valid)
+		return 0;
+
+	device = kzalloc(sizeof(struct its_device), GFP_KERNEL);
+	if (!device)
+		return -ENOMEM;
+
+	device->device_id = device_id;
+	INIT_LIST_HEAD(&device->itt_head);
+
+	list_add_tail(&device->dev_list, &its->device_list);
+
+	return 0;
+}
+
+static int vgic_its_nr_collection_ids(struct vgic_its *its)
+{
+	u64 r = its->baser_coll_table;
+
+	return (GITS_BASER_NR_PAGES(r) * SZ_64K) / GITS_BASER_ENTRY_SIZE(r);
+}
+
+/*
+ * The MAPC command maps collection IDs to redistributors.
+ * Must be called with the its_lock mutex held.
+ */
+static int vgic_its_cmd_handle_mapc(struct kvm *kvm, struct vgic_its *its,
+				    u64 *its_cmd)
+{
+	u16 coll_id;
+	u32 target_addr;
+	struct its_collection *collection;
+	bool valid;
+
+	valid = its_cmd_get_validbit(its_cmd);
+	coll_id = its_cmd_get_collection(its_cmd);
+	target_addr = its_cmd_get_target_addr(its_cmd);
+
+	if (target_addr >= atomic_read(&kvm->online_vcpus))
+		return E_ITS_MAPC_PROCNUM_OOR;
+
+	if (coll_id >= vgic_its_nr_collection_ids(its))
+		return E_ITS_MAPC_COLLECTION_OOR;
+
+	collection = find_collection(its, coll_id);
+
+	if (!valid) {
+		struct its_device *device;
+		struct its_itte *itte;
+		/*
+		 * Clearing the mapping for that collection ID removes the
+		 * entry from the list. If there wasn't any before, we can
+		 * go home early.
+		 */
+		if (!collection)
+			return 0;
+
+		for_each_lpi_its(device, itte, its)
+			if (itte->collection &&
+			    itte->collection->collection_id == coll_id)
+				itte->collection = NULL;
+
+		list_del(&collection->coll_list);
+		kfree(collection);
+	} else {
+		if (!collection) {
+			collection = kzalloc(sizeof(struct its_collection),
+					     GFP_KERNEL);
+			if (!collection)
+				return -ENOMEM;
+
+			vgic_its_init_collection(its, collection, coll_id);
+			collection->target_addr = target_addr;
+		} else {
+			collection->target_addr = target_addr;
+			update_affinity_collection(kvm, its, collection);
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * The CLEAR command removes the pending state for a particular LPI.
+ * Must be called with the its_lock mutex held.
+ */
+static int vgic_its_cmd_handle_clear(struct kvm *kvm, struct vgic_its *its,
+				     u64 *its_cmd)
+{
+	u32 device_id = its_cmd_get_deviceid(its_cmd);
+	u32 event_id = its_cmd_get_id(its_cmd);
+	struct its_itte *itte;
+
+
+	itte = find_itte(its, device_id, event_id);
+	if (!itte)
+		return E_ITS_CLEAR_UNMAPPED_INTERRUPT;
+
+	itte->irq->pending = false;
+
+	return 0;
+}
+
+/*
+ * The INV command syncs the configuration bits from the memory table.
+ * Must be called with the its_lock mutex held.
+ */
+static int vgic_its_cmd_handle_inv(struct kvm *kvm, struct vgic_its *its,
+				   u64 *its_cmd)
+{
+	u32 device_id = its_cmd_get_deviceid(its_cmd);
+	u32 event_id = its_cmd_get_id(its_cmd);
+	struct its_itte *itte;
+
+
+	itte = find_itte(its, device_id, event_id);
+	if (!itte)
+		return E_ITS_INV_UNMAPPED_INTERRUPT;
+
+	return update_lpi_config(kvm, itte->irq, NULL);
+}
+
+/*
+ * The INVALL command requests flushing of all IRQ data in this collection.
+ * Find the VCPU mapped to that collection, then iterate over the VM's list
+ * of mapped LPIs and update the configuration for each IRQ which targets
+ * the specified vcpu. The configuration will be read from the in-memory
+ * configuration table.
+ * Must be called with the its_lock mutex held.
+ */
+static int vgic_its_cmd_handle_invall(struct kvm *kvm, struct vgic_its *its,
+				      u64 *its_cmd)
+{
+	u32 coll_id = its_cmd_get_collection(its_cmd);
+	struct its_collection *collection;
+	struct kvm_vcpu *vcpu;
+	struct vgic_irq *irq;
+	u32 *intids;
+	int irq_count, i;
+
+	collection = find_collection(its, coll_id);
+	if (!its_is_collection_mapped(collection))
+		return E_ITS_INVALL_UNMAPPED_COLLECTION;
+
+	vcpu = kvm_get_vcpu(kvm, collection->target_addr);
+
+	irq_count = vgic_copy_lpi_list(kvm, &intids);
+	if (irq_count < 0)
+		return irq_count;
+
+	for (i = 0; i < irq_count; i++) {
+		irq = vgic_get_irq(kvm, NULL, intids[i]);
+		if (!irq)
+			continue;
+		update_lpi_config(kvm, irq, vcpu);
+		vgic_put_irq(kvm, irq);
+	}
+
+	kfree(intids);
+
+	return 0;
+}
+
+/*
+ * The MOVALL command moves the pending state of all IRQs targeting one
+ * redistributor to another. We don't hold the pending state in the VCPUs,
+ * but in the IRQs instead, so there is really not much to do for us here.
+ * However the spec says that no IRQ must target the old redistributor
+ * afterwards, so we make sure that no LPI is using the associated target_vcpu.
+ * This command affects all LPIs in the system that target that redistributor.
+ */
+static int vgic_its_cmd_handle_movall(struct kvm *kvm, struct vgic_its *its,
+				      u64 *its_cmd)
+{
+	struct vgic_dist *dist = &kvm->arch.vgic;
+	u32 target1_addr = its_cmd_get_target_addr(its_cmd);
+	u32 target2_addr = its_cmd_mask_field(its_cmd, 3, 16, 32);
+	struct kvm_vcpu *vcpu1, *vcpu2;
+	struct vgic_irq *irq;
+
+	if (target1_addr >= atomic_read(&kvm->online_vcpus) ||
+	    target2_addr >= atomic_read(&kvm->online_vcpus))
+		return E_ITS_MOVALL_PROCNUM_OOR;
+
+	if (target1_addr == target2_addr)
+		return 0;
+
+	vcpu1 = kvm_get_vcpu(kvm, target1_addr);
+	vcpu2 = kvm_get_vcpu(kvm, target2_addr);
+
+	spin_lock(&dist->lpi_list_lock);
+
+	list_for_each_entry(irq, &dist->lpi_list_head, lpi_list) {
+		spin_lock(&irq->irq_lock);
+
+		if (irq->target_vcpu == vcpu1)
+			irq->target_vcpu = vcpu2;
+
+		spin_unlock(&irq->irq_lock);
+	}
+
+	spin_unlock(&dist->lpi_list_lock);
+
+	return 0;
+}
+
+/*
+ * This function is called with the its_cmd lock held, but the ITS data
+ * structure lock dropped.
+ */
 static int vgic_its_handle_command(struct kvm *kvm, struct vgic_its *its,
 				   u64 *its_cmd)
 {
-	return -ENODEV;
+	u8 cmd = its_cmd_get_command(its_cmd);
+	int ret = -ENODEV;
+
+	mutex_lock(&its->its_lock);
+	switch (cmd) {
+	case GITS_CMD_MAPD:
+		ret = vgic_its_cmd_handle_mapd(kvm, its, its_cmd);
+		break;
+	case GITS_CMD_MAPC:
+		ret = vgic_its_cmd_handle_mapc(kvm, its, its_cmd);
+		break;
+	case GITS_CMD_MAPI:
+		ret = vgic_its_cmd_handle_mapi(kvm, its, its_cmd, cmd);
+		break;
+	case GITS_CMD_MAPTI:
+		ret = vgic_its_cmd_handle_mapi(kvm, its, its_cmd, cmd);
+		break;
+	case GITS_CMD_MOVI:
+		ret = vgic_its_cmd_handle_movi(kvm, its, its_cmd);
+		break;
+	case GITS_CMD_DISCARD:
+		ret = vgic_its_cmd_handle_discard(kvm, its, its_cmd);
+		break;
+	case GITS_CMD_CLEAR:
+		ret = vgic_its_cmd_handle_clear(kvm, its, its_cmd);
+		break;
+	case GITS_CMD_MOVALL:
+		ret = vgic_its_cmd_handle_movall(kvm, its, its_cmd);
+		break;
+	case GITS_CMD_INV:
+		ret = vgic_its_cmd_handle_inv(kvm, its, its_cmd);
+		break;
+	case GITS_CMD_INVALL:
+		ret = vgic_its_cmd_handle_invall(kvm, its, its_cmd);
+		break;
+	case GITS_CMD_SYNC:
+		/* we ignore this command: we are in sync all of the time */
+		ret = 0;
+		break;
+	}
+	mutex_unlock(&its->its_lock);
+
+	return ret;
 }
 
 static u64 vgic_sanitise_its_baser(u64 reg)
-- 
2.8.1