[v3,14/16] KVM: arm64: implement ITS command queue command handlers

Commit Message

Pavel Fedin Oct. 14, 2015, 12:26 p.m. UTC

Hello!

> -----Original Message-----
> From: [e-mail] [mailto:[e-mail]] On Behalf Of Andre Przywara
> Sent: Wednesday, October 07, 2015 5:55 PM
> To: [e-mail]; [e-mail]
> Cc: [e-mail]; [e-mail]; [e-mail]; linux-arm-
> [e-mail]; [e-mail]
> Subject: [PATCH v3 14/16] KVM: arm64: implement ITS command queue command handlers
> 
> The connection between a device, an event ID, the LPI number and the
> allocated 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 the ITS implementation use their own
> format.
> Implement handlers for the various ITS commands and let them store
> the requested relation into our own data structures.
> To avoid kmallocs inside the ITS spinlock, we preallocate possibly
> needed memory outside of the lock and free that if it turns out to
> be not needed (mostly error handling).
> Error handling is very basic at this point, as we don't have a good
> way of communicating errors to the guest (usually a SError).
> The INT command handler is missing at this point, as we gain the
> capability of actually injecting MSIs into the guest only later on.
> 
> Signed-off-by: Andre Przywara <[e-mail]>
> ---
> Changelog v2..v3:
> - adjust handlers to new pendbaser/propbaser locking scheme
> - properly free ITTEs (including pending bitmap)
> - fix handling of unmapped collections
> 
>  include/linux/irqchip/arm-gic-v3.h |   5 +-
>  virt/kvm/arm/its-emul.c            | 502 ++++++++++++++++++++++++++++++++++++-
>  virt/kvm/arm/its-emul.h            |  11 +
>  3 files changed, 516 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
> index ef274a9..27c0e75 100644
> --- a/include/linux/irqchip/arm-gic-v3.h
> +++ b/include/linux/irqchip/arm-gic-v3.h
> @@ -255,7 +255,10 @@
>   */
>  #define GITS_CMD_MAPD			0x08
>  #define GITS_CMD_MAPC			0x09
> -#define GITS_CMD_MAPVI			0x0a
> +#define GITS_CMD_MAPTI			0x0a
> +/* older GIC documentation used MAPVI for this command */
> +#define GITS_CMD_MAPVI			GITS_CMD_MAPTI
> +#define GITS_CMD_MAPI			0x0b
>  #define GITS_CMD_MOVI			0x01
>  #define GITS_CMD_DISCARD		0x0f
>  #define GITS_CMD_INV			0x0c
> diff --git a/virt/kvm/arm/its-emul.c b/virt/kvm/arm/its-emul.c
> index 7a8c5db..642effb 100644
> --- a/virt/kvm/arm/its-emul.c
> +++ b/virt/kvm/arm/its-emul.c
> @@ -22,6 +22,7 @@
>  #include <linux/kvm_host.h>
>  #include <linux/interrupt.h>
>  #include <linux/list.h>
> +#include <linux/slab.h>
> 
>  #include <linux/irqchip/arm-gic-v3.h>
>  #include <kvm/arm_vgic.h>
> @@ -64,6 +65,34 @@ struct its_itte {
>  	unsigned long *pending;
>  };
> 
> +static struct its_device *find_its_device(struct kvm *kvm, u32 device_id)
> +{
> +	struct vgic_its *its = &kvm->arch.vgic.its;
> +	struct its_device *device;
> +
> +	list_for_each_entry(device, &its->device_list, dev_list)
> +		if (device_id == device->device_id)
> +			return device;
> +
> +	return NULL;
> +}
> +
> +static struct its_itte *find_itte(struct kvm *kvm, u32 device_id, u32 event_id)
> +{
> +	struct its_device *device;
> +	struct its_itte *itte;
> +
> +	device = find_its_device(kvm, device_id);
> +	if (device == NULL)
> +		return NULL;
> +
> +	list_for_each_entry(itte, &device->itt, 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(dev, itte, kvm) \
>  	list_for_each_entry(dev, &(kvm)->arch.vgic.its.device_list, dev_list) \
> @@ -81,6 +110,19 @@ static struct its_itte *find_itte_by_lpi(struct kvm *kvm, int lpi)
>  	return NULL;
>  }
> 
> +static struct its_collection *find_collection(struct kvm *kvm, int coll_id)
> +{
> +	struct its_collection *collection;
> +
> +	list_for_each_entry(collection, &kvm->arch.vgic.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)
> 
> @@ -352,13 +394,471 @@ static void its_free_itte(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). */
> +static int vits_cmd_handle_discard(struct kvm *kvm, u64 *its_cmd)
> +{
> +	struct vgic_its *its = &kvm->arch.vgic.its;
> +	u32 device_id;
> +	u32 event_id;
> +	struct its_itte *itte;
> +	int ret = E_ITS_DISCARD_UNMAPPED_INTERRUPT;
> +
> +	device_id = its_cmd_get_deviceid(its_cmd);
> +	event_id = its_cmd_get_id(its_cmd);
> +
> +	spin_lock(&its->lock);
> +	itte = find_itte(kvm, 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(itte);
> +		ret = 0;
> +	}

 Are you sure that DISCARD should remove the entry? The doc says in 6.3.4:
--- cut ---
This command translates the event defined by EventID and DeviceID and instructs the appropriate Redistributor to
remove the pending state of the interrupt. It also ensures that any caching in the Redistributors associated with a
specific EventID is consistent with the configuration held in memory.
--- cut ---
 So, it seems to be like CLEAR + INV.

> +
> +	spin_unlock(&its->lock);
> +	return ret;
> +}
> +
> +/* The MOVI command moves an ITTE to a different collection. */
> +static int vits_cmd_handle_movi(struct kvm *kvm, u64 *its_cmd)
> +{
> +	struct vgic_its *its = &kvm->arch.vgic.its;
> +	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_collection *collection;
> +	int ret;
> +
> +	spin_lock(&its->lock);
> +	itte = find_itte(kvm, device_id, event_id);
> +	if (!itte) {
> +		ret = E_ITS_MOVI_UNMAPPED_INTERRUPT;
> +		goto out_unlock;
> +	}
> +	if (!its_is_collection_mapped(itte->collection)) {
> +		ret = E_ITS_MOVI_UNMAPPED_COLLECTION;
> +		goto out_unlock;
> +	}
> +
> +	collection = find_collection(kvm, coll_id);
> +	if (!its_is_collection_mapped(collection)) {
> +		ret = E_ITS_MOVI_UNMAPPED_COLLECTION;
> +		goto out_unlock;
> +	}
> +
> +	if (test_and_clear_bit(itte->collection->target_addr, itte->pending))
> +		__set_bit(collection->target_addr, itte->pending);
> +
> +	itte->collection = collection;
> +out_unlock:
> +	spin_unlock(&its->lock);
> +	return ret;
> +}
> +
> +static void vits_init_collection(struct kvm *kvm,
> +				 struct its_collection *collection,
> +				 u32 coll_id)
> +{
> +	collection->collection_id = coll_id;
> +	collection->target_addr = COLLECTION_NOT_MAPPED;
> +
> +	list_add_tail(&collection->coll_list,
> +		&kvm->arch.vgic.its.collection_list);
> +}
> +
> +/* The MAPTI and MAPI commands map LPIs to ITTEs. */
> +static int vits_cmd_handle_mapi(struct kvm *kvm, u64 *its_cmd, u8 cmd)
> +{
> +	struct vgic_dist *dist = &kvm->arch.vgic;
> +	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, *new_itte;
> +	struct its_device *device;
> +	struct its_collection *collection, *new_coll;
> +	int lpi_nr;
> +	int ret = 0;
> +
> +	/* Preallocate possibly needed memory here outside of the lock */
> +	new_coll = kmalloc(sizeof(struct its_collection), GFP_KERNEL);
> +	new_itte = kzalloc(sizeof(struct its_itte), GFP_KERNEL);
> +	if (new_itte)
> +		new_itte->pending = kcalloc(BITS_TO_LONGS(dist->nr_cpus),
> +					    sizeof(long), GFP_KERNEL);
> +
> +	spin_lock(&dist->its.lock);
> +
> +	device = find_its_device(kvm, device_id);
> +	if (!device) {
> +		ret = E_ITS_MAPTI_UNMAPPED_DEVICE;
> +		goto out_unlock;
> +	}
> +
> +	collection = find_collection(kvm, coll_id);
> +	if (!collection && !new_coll) {
> +		ret = -ENOMEM;
> +		goto out_unlock;
> +	}
> +
> +	if (cmd == 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 >= nr_idbits_propbase(dist->propbaser)) {
> +		ret = E_ITS_MAPTI_PHYSICALID_OOR;
> +		goto out_unlock;
> +	}
> +
> +	itte = find_itte(kvm, device_id, event_id);
> +	if (!itte) {
> +		if (!new_itte || !new_itte->pending) {
> +			ret = -ENOMEM;
> +			goto out_unlock;
> +		}
> +		itte = new_itte;
> +
> +		itte->event_id	= event_id;
> +		list_add_tail(&itte->itte_list, &device->itt);
> +	} else {
> +		if (new_itte)
> +			kfree(new_itte->pending);
> +		kfree(new_itte);
> +	}
> +
> +	if (!collection) {
> +		collection = new_coll;
> +		vits_init_collection(kvm, collection, coll_id);
> +	} else {
> +		kfree(new_coll);
> +	}
> +
> +	itte->collection = collection;
> +	itte->lpi = lpi_nr;
> +
> +out_unlock:
> +	spin_unlock(&dist->its.lock);
> +	if (ret) {
> +		kfree(new_coll);
> +		if (new_itte)
> +			kfree(new_itte->pending);
> +		kfree(new_itte);
> +	}
> +	return ret;
> +}
> +
> +static void vits_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, itte_list)
> +		its_free_itte(itte);
> +
> +	list_del(&device->dev_list);
> +	kfree(device);
> +}
> +
> +/* MAPD maps or unmaps a device ID to Interrupt Translation Tables (ITTs). */
> +static int vits_cmd_handle_mapd(struct kvm *kvm, u64 *its_cmd)
> +{
> +	struct vgic_its *its = &kvm->arch.vgic.its;
> +	bool valid = its_cmd_get_validbit(its_cmd);
> +	u32 device_id = its_cmd_get_deviceid(its_cmd);
> +	struct its_device *device, *new_device = NULL;
> +
> +	/* We preallocate memory outside of the lock here */
> +	if (valid) {
> +		new_device = kzalloc(sizeof(struct its_device), GFP_KERNEL);
> +		if (!new_device)
> +			return -ENOMEM;
> +	}
> +
> +	spin_lock(&its->lock);
> +
> +	device = find_its_device(kvm, device_id);
> +	if (device)
> +		vits_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)
> +		goto out_unlock;
> +
> +	device = new_device;
> +
> +	device->device_id = device_id;
> +	INIT_LIST_HEAD(&device->itt);
> +
> +	list_add_tail(&device->dev_list,
> +		      &kvm->arch.vgic.its.device_list);
> +
> +out_unlock:
> +	spin_unlock(&its->lock);
> +	return 0;
> +}
> +
> +/* The MAPC command maps collection IDs to redistributors. */
> +static int vits_cmd_handle_mapc(struct kvm *kvm, u64 *its_cmd)
> +{
> +	struct vgic_its *its = &kvm->arch.vgic.its;
> +	u16 coll_id;
> +	u32 target_addr;
> +	struct its_collection *collection, *new_coll = NULL;
> +	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;
> +
> +	/* We preallocate memory outside of the lock here */
> +	if (valid) {
> +		new_coll = kmalloc(sizeof(struct its_collection), GFP_KERNEL);
> +		if (!new_coll)
> +			return -ENOMEM;
> +	}
> +
> +	spin_lock(&its->lock);
> +	collection = find_collection(kvm, 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)
> +			goto out_unlock;
> +
> +		for_each_lpi(device, itte, kvm)
> +			if (itte->collection &&
> +			    itte->collection->collection_id == coll_id)
> +				itte->collection = NULL;
> +
> +		list_del(&collection->coll_list);
> +		kfree(collection);
> +	} else {
> +		if (!collection)
> +			collection = new_coll;
> +		else
> +			kfree(new_coll);
> +
> +		vits_init_collection(kvm, collection, coll_id);
> +		collection->target_addr = target_addr;
> +	}
> +
> +out_unlock:
> +	spin_unlock(&its->lock);
> +	return 0;
> +}
> +
> +/* The CLEAR command removes the pending state for a particular LPI. */
> +static int vits_cmd_handle_clear(struct kvm *kvm, u64 *its_cmd)
> +{
> +	struct vgic_its *its = &kvm->arch.vgic.its;
> +	u32 device_id;
> +	u32 event_id;
> +	struct its_itte *itte;
> +	int ret = 0;
> +
> +	device_id = its_cmd_get_deviceid(its_cmd);
> +	event_id = its_cmd_get_id(its_cmd);
> +
> +	spin_lock(&its->lock);
> +
> +	itte = find_itte(kvm, device_id, event_id);
> +	if (!itte) {
> +		ret = E_ITS_CLEAR_UNMAPPED_INTERRUPT;
> +		goto out_unlock;
> +	}
> +
> +	if (its_is_collection_mapped(itte->collection))
> +		__clear_bit(itte->collection->target_addr, itte->pending);
> +
> +out_unlock:
> +	spin_unlock(&its->lock);
> +	return ret;
> +}
> +
> +/* The INV command syncs the configuration bits from the memory tables. */
> +static int vits_cmd_handle_inv(struct kvm *kvm, u64 *its_cmd)
> +{
> +	struct vgic_dist *dist = &kvm->arch.vgic;
> +	u32 device_id;
> +	u32 event_id;
> +	struct its_itte *itte, *new_itte;
> +	gpa_t propbase;
> +	int ret;
> +	u8 prop;
> +
> +	device_id = its_cmd_get_deviceid(its_cmd);
> +	event_id = its_cmd_get_id(its_cmd);
> +
> +	spin_lock(&dist->its.lock);
> +	itte = find_itte(kvm, device_id, event_id);
> +	spin_unlock(&dist->its.lock);
> +	if (!itte)
> +		return E_ITS_INV_UNMAPPED_INTERRUPT;
> +
> +	/*
> +	 * We cannot read from guest memory inside the spinlock, so we
> +	 * need to re-read our tables to learn whether the LPI number we are
> +	 * using is still valid.
> +	 */
> +	do {
> +		propbase = BASER_BASE_ADDRESS(dist->propbaser);
> +		ret = kvm_read_guest(kvm, propbase + itte->lpi - GIC_LPI_OFFSET,
> +				     &prop, 1);
> +		if (ret)
> +			return ret;
> +
> +		spin_lock(&dist->its.lock);
> +		new_itte = find_itte(kvm, device_id, event_id);
> +		if (new_itte->lpi != itte->lpi) {
> +			itte = new_itte;
> +			spin_unlock(&dist->its.lock);
> +			continue;
> +		}
> +		update_lpi_config(kvm, itte, prop);
> +		spin_unlock(&dist->its.lock);
> +	} while (0);
> +	return 0;
> +}
> +
> +/* The INVALL command requests flushing of all IRQ data in this collection. */
> +static int vits_cmd_handle_invall(struct kvm *kvm, u64 *its_cmd)
> +{
> +	struct vgic_dist *dist = &kvm->arch.vgic;
> +	u64 prop_base_reg, pend_base_reg;
> +	u32 coll_id = its_cmd_get_collection(its_cmd);
> +	struct its_collection *collection;
> +	struct kvm_vcpu *vcpu;
> +
> +	collection = find_collection(kvm, coll_id);
> +	if (!its_is_collection_mapped(collection))
> +		return E_ITS_INVALL_UNMAPPED_COLLECTION;
> +
> +	vcpu = kvm_get_vcpu(kvm, collection->target_addr);
> +
> +	spin_lock(&dist->lock);
> +	pend_base_reg = dist->pendbaser[vcpu->vcpu_id];
> +	prop_base_reg = dist->propbaser;
> +	spin_unlock(&dist->lock);
> +
> +	its_update_lpis_configuration(kvm, prop_base_reg);
> +	its_sync_lpi_pending_table(vcpu, pend_base_reg);
> +
> +	return 0;
> +}
> +
> +/* The MOVALL command moves all IRQs from one redistributor to another. */
> +static int vits_cmd_handle_movall(struct kvm *kvm, u64 *its_cmd)
> +{
> +	struct vgic_its *its = &kvm->arch.vgic.its;
> +	u32 target1_addr = its_cmd_get_target_addr(its_cmd);
> +	u32 target2_addr = its_cmd_mask_field(its_cmd, 3, 16, 32);
> +	struct its_collection *collection;
> +	struct its_device *device;
> +	struct its_itte *itte;
> +
> +	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;
> +
> +	spin_lock(&its->lock);
> +	for_each_lpi(device, itte, kvm) {
> +		/* remap all collections mapped to target address 1 */
> +		collection = itte->collection;
> +		if (collection && collection->target_addr == target1_addr)
> +			collection->target_addr = target2_addr;
> +
> +		/* move pending state if LPI is affected */
> +		if (test_and_clear_bit(target1_addr, itte->pending))
> +			__set_bit(target2_addr, itte->pending);
> +	}
> +
> +	spin_unlock(&its->lock);
> +	return 0;
> +}
> +
>  /*
>   * This function is called with both the ITS and the distributor lock dropped,
>   * so the actual command handlers must take the respective locks when needed.
>   */
>  static int vits_handle_command(struct kvm_vcpu *vcpu, u64 *its_cmd)
>  {
> -	return -ENODEV;
> +	u8 cmd = its_cmd_get_command(its_cmd);
> +	int ret = -ENODEV;
> +
> +	switch (cmd) {
> +	case GITS_CMD_MAPD:
> +		ret = vits_cmd_handle_mapd(vcpu->kvm, its_cmd);
> +		break;
> +	case GITS_CMD_MAPC:
> +		ret = vits_cmd_handle_mapc(vcpu->kvm, its_cmd);
> +		break;
> +	case GITS_CMD_MAPI:
> +		ret = vits_cmd_handle_mapi(vcpu->kvm, its_cmd, cmd);
> +		break;
> +	case GITS_CMD_MAPTI:
> +		ret = vits_cmd_handle_mapi(vcpu->kvm, its_cmd, cmd);
> +		break;
> +	case GITS_CMD_MOVI:
> +		ret = vits_cmd_handle_movi(vcpu->kvm, its_cmd);
> +		break;
> +	case GITS_CMD_DISCARD:
> +		ret = vits_cmd_handle_discard(vcpu->kvm, its_cmd);
> +		break;
> +	case GITS_CMD_CLEAR:
> +		ret = vits_cmd_handle_clear(vcpu->kvm, its_cmd);
> +		break;
> +	case GITS_CMD_MOVALL:
> +		ret = vits_cmd_handle_movall(vcpu->kvm, its_cmd);
> +		break;
> +	case GITS_CMD_INV:
> +		ret = vits_cmd_handle_inv(vcpu->kvm, its_cmd);
> +		break;
> +	case GITS_CMD_INVALL:
> +		ret = vits_cmd_handle_invall(vcpu->kvm, its_cmd);
> +		break;
> +	case GITS_CMD_SYNC:
> +		/* we ignore this command: we are in sync all of the time */
> +		ret = 0;
> +		break;
> +	}
> +
> +	return ret;
>  }
> 
>  static bool handle_mmio_gits_cbaser(struct kvm_vcpu *vcpu,
> diff --git a/virt/kvm/arm/its-emul.h b/virt/kvm/arm/its-emul.h
> index cbc3877..830524a 100644
> --- a/virt/kvm/arm/its-emul.h
> +++ b/virt/kvm/arm/its-emul.h
> @@ -39,4 +39,15 @@ void vits_destroy(struct kvm *kvm);
>  bool vits_queue_lpis(struct kvm_vcpu *vcpu);
>  void vits_unqueue_lpi(struct kvm_vcpu *vcpu, int irq);
> 
> +#define E_ITS_MOVI_UNMAPPED_INTERRUPT		0x010107
> +#define E_ITS_MOVI_UNMAPPED_COLLECTION		0x010109
> +#define E_ITS_CLEAR_UNMAPPED_INTERRUPT		0x010507
> +#define E_ITS_MAPC_PROCNUM_OOR			0x010902
> +#define E_ITS_MAPTI_UNMAPPED_DEVICE		0x010a04
> +#define E_ITS_MAPTI_PHYSICALID_OOR		0x010a06
> +#define E_ITS_INV_UNMAPPED_INTERRUPT		0x010c07
> +#define E_ITS_INVALL_UNMAPPED_COLLECTION	0x010d09
> +#define E_ITS_MOVALL_PROCNUM_OOR		0x010e01
> +#define E_ITS_DISCARD_UNMAPPED_INTERRUPT	0x010f07

 Did you just invent PROCNUM_OOR? Additionally, you have two different suffixes for it, this goes against the concept.
 Actually, your error handling is IMHO too stripped down. I can suggest you to squash in the following patch below, it significantly
improves error recognition. Yes, i know that status register isn't implemented (or at least error code goes nowhere).

> +
>  #endif
> --

---
From 6da01d44c5b3753610b2a87724aedc2b05f42e06 Mon Sep 17 00:00:00 2001
From: Pavel Fedin <[e-mail]>
Date: Wed, 14 Oct 2015 15:14:07 +0300
Subject: [PATCH] KVM: arm64: Improve ITS error handling

Remember ITT size and check device IDs against it. Also, factor out
its_find_itte_in_device() for convenience.

Error codes generalized accross commands. When status register is
implemented, in order to complete error code, command code should be
echoed back in bits 15...8.
---
 virt/kvm/arm/its-emul.c | 86 +++++++++++++++++++++++++++++++------------------
 virt/kvm/arm/its-emul.h | 15 +++------
 2 files changed, 59 insertions(+), 42 deletions(-)

Patch

diff --git a/virt/kvm/arm/its-emul.c b/virt/kvm/arm/its-emul.c
index 2fcd844..181bec8 100644
--- a/virt/kvm/arm/its-emul.c
+++ b/virt/kvm/arm/its-emul.c
@@ -40,6 +40,7 @@  struct its_device {
 	/* the head for the list of ITTEs */
 	struct list_head itt;
 	u32 device_id;
+	u32 itt_size;
 };
 
 #define COLLECTION_NOT_MAPPED ((u32)-1)
@@ -77,15 +78,11 @@  static struct its_device *find_its_device(struct kvm *kvm, u32 device_id)
 	return NULL;
 }
 
-static struct its_itte *find_itte(struct kvm *kvm, u32 device_id, u32 event_id)
+static struct its_itte *find_itte_in_device(struct its_device *device,
+					    u32 event_id)
 {
-	struct its_device *device;
 	struct its_itte *itte;
 
-	device = find_its_device(kvm, device_id);
-	if (device == NULL)
-		return NULL;
-
 	list_for_each_entry(itte, &device->itt, itte_list)
 		if (itte->event_id == event_id)
 			return itte;
@@ -93,6 +90,28 @@  static struct its_itte *find_itte(struct kvm *kvm, u32 device_id, u32 event_id)
 	return NULL;
 }
 
+static struct its_itte *find_itte(struct kvm *kvm, u32 device_id,
+				  u32 event_id, int *err)
+{
+	struct its_device *device;
+	struct its_itte *itte;
+
+	device = find_its_device(kvm, device_id);
+	if (device == NULL) {
+		*err = E_ITS_UNMAPPED_DEVICE;
+		return NULL;
+	}
+
+	if (event_id >= 2 << device->itt_size) {
+		*err = E_ITS_ID_OOR;
+		return NULL;
+	}
+
+	itte = find_itte_in_device(device, event_id);
+	*err = itte ? 0 : E_ITS_UNMAPPED_INTERRUPT;
+	return itte;
+}
+
 /* To be used as an iterator this macro misses the enclosing parentheses */
 #define for_each_lpi(dev, itte, kvm) \
 	list_for_each_entry(dev, &(kvm)->arch.vgic.its.device_list, dev_list) \
@@ -359,10 +378,12 @@  int vits_inject_msi(struct kvm *kvm, struct kvm_msi *msi)
 		goto out_unlock;
 	}
 
-	itte = find_itte(kvm, msi->devid, msi->data);
+	itte = find_itte(kvm, msi->devid, msi->data, &ret);
 	/* Triggering an unmapped IRQ gets silently dropped. */
-	if (!itte || !its_is_collection_mapped(itte->collection))
+	if (!itte || !its_is_collection_mapped(itte->collection)) {
+		ret = 0;
 		goto out_unlock;
+	}
 
 	cpuid = itte->collection->target_addr;
 	__set_bit(cpuid, itte->pending);
@@ -476,6 +497,7 @@  static u64 its_cmd_mask_field(u64 *its_cmd, int word, int shift, int size)
 
 #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_size(cmd)		its_cmd_mask_field(cmd, 1,  0,  5)
 #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)
@@ -489,21 +511,23 @@  static int vits_cmd_handle_discard(struct kvm *kvm, u64 *its_cmd)
 	u32 device_id;
 	u32 event_id;
 	struct its_itte *itte;
-	int ret = E_ITS_DISCARD_UNMAPPED_INTERRUPT;
+	int ret;
 
 	device_id = its_cmd_get_deviceid(its_cmd);
 	event_id = its_cmd_get_id(its_cmd);
 
 	spin_lock(&its->lock);
-	itte = find_itte(kvm, device_id, event_id);
-	if (itte && itte->collection) {
+	itte = find_itte(kvm, device_id, event_id, &ret);
+	if (itte) {
 		/*
 		 * 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(itte);
-		ret = 0;
+		if (itte->collection)
+			its_free_itte(itte);
+		else
+			ret = E_ITS_UNMAPPED_INTERRUPT;
 	}
 
 	spin_unlock(&its->lock);
@@ -522,19 +546,18 @@  static int vits_cmd_handle_movi(struct kvm *kvm, u64 *its_cmd)
 	int ret;
 
 	spin_lock(&its->lock);
-	itte = find_itte(kvm, device_id, event_id);
-	if (!itte) {
-		ret = E_ITS_MOVI_UNMAPPED_INTERRUPT;
+	itte = find_itte(kvm, device_id, event_id, &ret);
+	if (!itte)
 		goto out_unlock;
-	}
+
 	if (!its_is_collection_mapped(itte->collection)) {
-		ret = E_ITS_MOVI_UNMAPPED_COLLECTION;
+		ret = E_ITS_UNMAPPED_COLLECTION;
 		goto out_unlock;
 	}
 
 	collection = find_collection(kvm, coll_id);
 	if (!its_is_collection_mapped(collection)) {
-		ret = E_ITS_MOVI_UNMAPPED_COLLECTION;
+		ret = E_ITS_UNMAPPED_COLLECTION;
 		goto out_unlock;
 	}
 
@@ -582,7 +605,7 @@  static int vits_cmd_handle_mapi(struct kvm *kvm, u64 *its_cmd, u8 cmd)
 
 	device = find_its_device(kvm, device_id);
 	if (!device) {
-		ret = E_ITS_MAPTI_UNMAPPED_DEVICE;
+		ret = E_ITS_UNMAPPED_DEVICE;
 		goto out_unlock;
 	}
 
@@ -598,11 +621,11 @@  static int vits_cmd_handle_mapi(struct kvm *kvm, u64 *its_cmd, u8 cmd)
 		lpi_nr = event_id;
 	if (lpi_nr < GIC_LPI_OFFSET ||
 	    lpi_nr >= nr_idbits_propbase(dist->propbaser)) {
-		ret = E_ITS_MAPTI_PHYSICALID_OOR;
+		ret = E_ITS_PHYSICALID_OOR;
 		goto out_unlock;
 	}
 
-	itte = find_itte(kvm, device_id, event_id);
+	itte = find_itte_in_device(device, event_id);
 	if (!itte) {
 		if (!new_itte || !new_itte->pending) {
 			ret = -ENOMEM;
@@ -686,6 +709,7 @@  static int vits_cmd_handle_mapd(struct kvm *kvm, u64 *its_cmd)
 	device = new_device;
 
 	device->device_id = device_id;
+	device->itt_size = its_cmd_get_size(its_cmd);
 	INIT_LIST_HEAD(&device->itt);
 
 	list_add_tail(&device->dev_list,
@@ -710,7 +734,7 @@  static int vits_cmd_handle_mapc(struct kvm *kvm, u64 *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;
+		return -EINVAL;
 
 	/* We preallocate memory outside of the lock here */
 	if (valid) {
@@ -769,11 +793,9 @@  static int vits_cmd_handle_clear(struct kvm *kvm, u64 *its_cmd)
 
 	spin_lock(&its->lock);
 
-	itte = find_itte(kvm, device_id, event_id);
-	if (!itte) {
-		ret = E_ITS_CLEAR_UNMAPPED_INTERRUPT;
+	itte = find_itte(kvm, device_id, event_id, &ret);
+	if (!itte)
 		goto out_unlock;
-	}
 
 	if (its_is_collection_mapped(itte->collection))
 		__clear_bit(itte->collection->target_addr, itte->pending);
@@ -798,10 +820,10 @@  static int vits_cmd_handle_inv(struct kvm *kvm, u64 *its_cmd)
 	event_id = its_cmd_get_id(its_cmd);
 
 	spin_lock(&dist->its.lock);
-	itte = find_itte(kvm, device_id, event_id);
+	itte = find_itte(kvm, device_id, event_id, &ret);
 	spin_unlock(&dist->its.lock);
 	if (!itte)
-		return E_ITS_INV_UNMAPPED_INTERRUPT;
+		return ret;
 
 	/*
 	 * We cannot read from guest memory inside the spinlock, so we
@@ -816,7 +838,7 @@  static int vits_cmd_handle_inv(struct kvm *kvm, u64 *its_cmd)
 			return ret;
 
 		spin_lock(&dist->its.lock);
-		new_itte = find_itte(kvm, device_id, event_id);
+		new_itte = find_itte(kvm, device_id, event_id, &ret);
 		if (new_itte->lpi != itte->lpi) {
 			itte = new_itte;
 			spin_unlock(&dist->its.lock);
@@ -839,7 +861,7 @@  static int vits_cmd_handle_invall(struct kvm *kvm, u64 *its_cmd)
 
 	collection = find_collection(kvm, coll_id);
 	if (!its_is_collection_mapped(collection))
-		return E_ITS_INVALL_UNMAPPED_COLLECTION;
+		return E_ITS_UNMAPPED_COLLECTION;
 
 	vcpu = kvm_get_vcpu(kvm, collection->target_addr);
 
@@ -866,7 +888,7 @@  static int vits_cmd_handle_movall(struct kvm *kvm, u64 *its_cmd)
 
 	if (target1_addr >= atomic_read(&kvm->online_vcpus) ||
 	    target2_addr >= atomic_read(&kvm->online_vcpus))
-		return E_ITS_MOVALL_PROCNUM_OOR;
+		return -EINVAL;
 
 	if (target1_addr == target2_addr)
 		return 0;
diff --git a/virt/kvm/arm/its-emul.h b/virt/kvm/arm/its-emul.h
index f7fa5f8..56161d9 100644
--- a/virt/kvm/arm/its-emul.h
+++ b/virt/kvm/arm/its-emul.h
@@ -43,15 +43,10 @@  bool vits_queue_lpis(struct kvm_vcpu *vcpu);
 void vits_unqueue_lpi(struct kvm_vcpu *vcpu, int irq);
 bool vits_check_lpis(struct kvm_vcpu *vcpu);
 
-#define E_ITS_MOVI_UNMAPPED_INTERRUPT		0x010107
-#define E_ITS_MOVI_UNMAPPED_COLLECTION		0x010109
-#define E_ITS_CLEAR_UNMAPPED_INTERRUPT		0x010507
-#define E_ITS_MAPC_PROCNUM_OOR			0x010902
-#define E_ITS_MAPTI_UNMAPPED_DEVICE		0x010a04
-#define E_ITS_MAPTI_PHYSICALID_OOR		0x010a06
-#define E_ITS_INV_UNMAPPED_INTERRUPT		0x010c07
-#define E_ITS_INVALL_UNMAPPED_COLLECTION	0x010d09
-#define E_ITS_MOVALL_PROCNUM_OOR		0x010e01
-#define E_ITS_DISCARD_UNMAPPED_INTERRUPT	0x010f07
+#define E_ITS_UNMAPPED_DEVICE		0x010004
+#define E_ITS_ID_OOR			0x010005
+#define E_ITS_PHYSICALID_OOR		0x010006
+#define E_ITS_UNMAPPED_INTERRUPT	0x010007
+#define E_ITS_UNMAPPED_COLLECTION	0x010009
 
 #endif