Re: [RFC v3 1/2] vfio/platform: add support for msi

[Auger Eric <eric.auger@redhat.com>]

Hi Vikas,

On 12/14/20 6:45 PM, Vikas Gupta wrote:
> MSI support for platform devices.The MSI block
> is added as an extended IRQ which exports caps
> VFIO_IRQ_INFO_CAP_TYPE and VFIO_IRQ_INFO_CAP_MSI_DESCS.
> 
> Signed-off-by: Vikas Gupta <vikas.gupta@broadcom.com>
> ---
>  drivers/vfio/platform/vfio_platform_common.c  | 179 +++++++++++-
>  drivers/vfio/platform/vfio_platform_irq.c     | 260 +++++++++++++++++-
>  drivers/vfio/platform/vfio_platform_private.h |  32 +++
>  include/uapi/linux/vfio.h                     |  44 +++
>  4 files changed, 496 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index fb4b385191f2..c936852f35d7 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -16,6 +16,7 @@
>  #include <linux/types.h>
>  #include <linux/uaccess.h>
>  #include <linux/vfio.h>
> +#include <linux/nospec.h>
>  
>  #include "vfio_platform_private.h"
>  
> @@ -26,6 +27,8 @@
>  #define VFIO_PLATFORM_IS_ACPI(vdev) ((vdev)->acpihid != NULL)
>  
>  static LIST_HEAD(reset_list);
> +/* devices having MSI support */
nit: for devices using MSIs?
> +static LIST_HEAD(msi_list);
>  static DEFINE_MUTEX(driver_lock);
>  
>  static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
> @@ -47,6 +50,25 @@ static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
>  	return reset_fn;
>  }
>  
> +static bool vfio_platform_lookup_msi(struct vfio_platform_device *vdev)
> +{
> +	bool has_msi = false;
> +	struct vfio_platform_msi_node *iter;
> +
> +	mutex_lock(&driver_lock);
> +	list_for_each_entry(iter, &msi_list, link) {
> +		if (!strcmp(iter->compat, vdev->compat) &&
> +		    try_module_get(iter->owner)) {
> +			vdev->msi_module = iter->owner;
> +			vdev->of_get_msi = iter->of_get_msi;
> +			has_msi = true;
> +			break;
> +		}
> +	}
> +	mutex_unlock(&driver_lock);
> +	return has_msi;
> +}
> +
>  static int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
>  				    struct device *dev)
>  {
> @@ -126,6 +148,19 @@ static int vfio_platform_get_reset(struct vfio_platform_device *vdev)
>  	return vdev->of_reset ? 0 : -ENOENT;
>  }
>  
> +static int vfio_platform_get_msi(struct vfio_platform_device *vdev)
> +{
> +	bool has_msi;
> +
> +	has_msi = vfio_platform_lookup_msi(vdev);
> +	if (!has_msi) {
> +		request_module("vfio-msi:%s", vdev->compat);
> +		has_msi = vfio_platform_lookup_msi(vdev);
> +	}
> +
> +	return has_msi ? 0 : -ENOENT;
> +}
> +
>  static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
>  {
>  	if (VFIO_PLATFORM_IS_ACPI(vdev))
> @@ -135,6 +170,12 @@ static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
>  		module_put(vdev->reset_module);
>  }
>  
> +static void vfio_platform_put_msi(struct vfio_platform_device *vdev)
> +{
> +	if (vdev->of_get_msi)
> +		module_put(vdev->msi_module);
> +}
> +
>  static int vfio_platform_regions_init(struct vfio_platform_device *vdev)
>  {
>  	int cnt = 0, i;
> @@ -343,9 +384,17 @@ static long vfio_platform_ioctl(void *device_data,
>  
>  	} else if (cmd == VFIO_DEVICE_GET_IRQ_INFO) {
>  		struct vfio_irq_info info;
> +		struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
> +		struct vfio_irq_info_cap_msi *msi_info = NULL;
> +		int ext_irq_index = vdev->num_irqs - vdev->num_ext_irqs;
> +		unsigned long capsz;
> +		u32 index;
>  
>  		minsz = offsetofend(struct vfio_irq_info, count);
>  
> +		/* For backward compatibility, cannot require this */
> +		capsz = offsetofend(struct vfio_irq_info, cap_offset);
> +
>  		if (copy_from_user(&info, (void __user *)arg, minsz))
>  			return -EFAULT;
>  
> @@ -355,8 +404,94 @@ static long vfio_platform_ioctl(void *device_data,
>  		if (info.index >= vdev->num_irqs)
>  			return -EINVAL;
>  
> -		info.flags = vdev->irqs[info.index].flags;
> -		info.count = vdev->irqs[info.index].count;
> +		if (info.argsz >= capsz)
> +			minsz = capsz;
> +
> +		index = info.index;
> +
> +		info.flags = vdev->irqs[index].flags;
> +		info.count = vdev->irqs[index].count;
> +
> +		if (ext_irq_index - index == VFIO_EXT_IRQ_MSI) {
> +			struct vfio_irq_info_cap_type cap_type = {
> +				.header.id = VFIO_IRQ_INFO_CAP_TYPE,
> +				.header.version = 1 };
> +			struct vfio_platform_irq *irq;
> +			size_t msi_info_size;
> +			int num_msgs;
> +			int ret;
> +			int i;
> +
> +			index = array_index_nospec(index,
> +						   vdev->num_irqs);
> +			irq = &vdev->irqs[index];
> +
> +			cap_type.type = irq->type;
> +			cap_type.subtype = irq->subtype;
> +
> +			ret = vfio_info_add_capability(&caps,
> +						       &cap_type.header,
> +						       sizeof(cap_type));
> +			if (ret)
> +				return ret;
> +
> +			num_msgs = irq->num_ctx;
> +			if (num_msgs) {
> +				msi_info_size = struct_size(msi_info,
> +							    msgs, num_msgs);
> +
> +				msi_info = kzalloc(msi_info_size, GFP_KERNEL);
> +				if (!msi_info) {
> +					kfree(caps.buf);
> +					return -ENOMEM;
> +				}
> +
> +				msi_info->header.id =
> +						VFIO_IRQ_INFO_CAP_MSI_DESCS;
I thought you would remove this cap now the module is back. What is the
motivation to keep it?

Thanks

Eric
> +				msi_info->header.version = 1;
> +				msi_info->nr_msgs = num_msgs;
> +
> +				for (i = 0; i < num_msgs; i++) {
> +					struct vfio_irq_ctx *ctx = &irq->ctx[i];
> +
> +					msi_info->msgs[i].addr_lo =
> +							ctx->msg.address_lo;
> +					msi_info->msgs[i].addr_hi =
> +							ctx->msg.address_hi;
> +					msi_info->msgs[i].data = ctx->msg.data;
> +				}
> +
> +				ret = vfio_info_add_capability(&caps,
> +							&msi_info->header,
> +							msi_info_size);
> +				if (ret) {
> +					kfree(msi_info);
> +					kfree(caps.buf);
> +					return ret;
> +				}
> +			}
> +		}
> +
> +		if (caps.size) {
> +			info.flags |= VFIO_IRQ_INFO_FLAG_CAPS;
> +			if (info.argsz < sizeof(info) + caps.size) {
> +				info.argsz = sizeof(info) + caps.size;
> +				info.cap_offset = 0;
> +			} else {
> +				vfio_info_cap_shift(&caps, sizeof(info));
> +				if (copy_to_user((void __user *)arg +
> +						  sizeof(info), caps.buf,
> +						  caps.size)) {
> +					kfree(msi_info);
> +					kfree(caps.buf);
> +					return -EFAULT;
> +				}
> +				info.cap_offset = sizeof(info);
> +			}
> +
> +			kfree(msi_info);
> +			kfree(caps.buf);
> +		}
>  
>  		return copy_to_user((void __user *)arg, &info, minsz) ?
>  			-EFAULT : 0;
> @@ -365,6 +500,7 @@ static long vfio_platform_ioctl(void *device_data,
>  		struct vfio_irq_set hdr;
>  		u8 *data = NULL;
>  		int ret = 0;
> +		int max;
>  		size_t data_size = 0;
>  
>  		minsz = offsetofend(struct vfio_irq_set, count);
> @@ -372,8 +508,14 @@ static long vfio_platform_ioctl(void *device_data,
>  		if (copy_from_user(&hdr, (void __user *)arg, minsz))
>  			return -EFAULT;
>  
> -		ret = vfio_set_irqs_validate_and_prepare(&hdr, vdev->num_irqs,
> -						 vdev->num_irqs, &data_size);
> +		if (hdr.index >= vdev->num_irqs)
> +			return -EINVAL;
> +
> +		max = vdev->irqs[hdr.index].count;
> +
> +		ret = vfio_set_irqs_validate_and_prepare(&hdr, max,
> +							 vdev->num_irqs,
> +							 &data_size);
>  		if (ret)
>  			return ret;
>  
> @@ -678,6 +820,10 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
>  		return ret;
>  	}
>  
> +	ret = vfio_platform_get_msi(vdev);
> +	if (ret)
> +		dev_info(vdev->device, "msi not supported\n");
I don't think we should output this message. This is printed for
amd-xgbe which does not have msi so this is misleading. I would say
either the vfio_platform_get_msi() can return an actual error or we
return a void?

Thanks

Eric
> +
>  	group = vfio_iommu_group_get(dev);
>  	if (!group) {
>  		dev_err(dev, "No IOMMU group for device %s\n", vdev->name);
> @@ -697,6 +843,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
>  put_iommu:
>  	vfio_iommu_group_put(group, dev);
>  put_reset:
> +	vfio_platform_put_msi(vdev);
>  	vfio_platform_put_reset(vdev);
>  	return ret;
>  }
> @@ -744,6 +891,30 @@ void vfio_platform_unregister_reset(const char *compat,
>  }
>  EXPORT_SYMBOL_GPL(vfio_platform_unregister_reset);
>  
> +void __vfio_platform_register_msi(struct vfio_platform_msi_node *node)
> +{
> +	mutex_lock(&driver_lock);
> +	list_add(&node->link, &msi_list);
> +	mutex_unlock(&driver_lock);
> +}
> +EXPORT_SYMBOL_GPL(__vfio_platform_register_msi);
> +
> +void vfio_platform_unregister_msi(const char *compat)
> +{
> +	struct vfio_platform_msi_node *iter, *temp;
> +
> +	mutex_lock(&driver_lock);
> +	list_for_each_entry_safe(iter, temp, &msi_list, link) {
> +		if (!strcmp(iter->compat, compat)) {
> +			list_del(&iter->link);
> +			break;
> +		}
> +	}
> +
> +	mutex_unlock(&driver_lock);
> +}
> +EXPORT_SYMBOL_GPL(vfio_platform_unregister_msi);
> +
>  MODULE_VERSION(DRIVER_VERSION);
>  MODULE_LICENSE("GPL v2");
>  MODULE_AUTHOR(DRIVER_AUTHOR);
> diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
> index c5b09ec0a3c9..e0f4696afedd 100644
> --- a/drivers/vfio/platform/vfio_platform_irq.c
> +++ b/drivers/vfio/platform/vfio_platform_irq.c
> @@ -8,10 +8,12 @@
>  
>  #include <linux/eventfd.h>
>  #include <linux/interrupt.h>
> +#include <linux/eventfd.h>
>  #include <linux/slab.h>
>  #include <linux/types.h>
>  #include <linux/vfio.h>
>  #include <linux/irq.h>
> +#include <linux/msi.h>
>  
>  #include "vfio_platform_private.h"
>  
> @@ -253,6 +255,195 @@ static int vfio_platform_set_irq_trigger(struct vfio_platform_device *vdev,
>  	return 0;
>  }
>  
> +/* MSI/MSIX */
> +static irqreturn_t vfio_msihandler(int irq, void *arg)
> +{
> +	struct eventfd_ctx *trigger = arg;
> +
> +	eventfd_signal(trigger, 1);
> +	return IRQ_HANDLED;
> +}
> +
> +static void msi_write(struct msi_desc *desc, struct msi_msg *msg)
> +{
> +	int i;
> +	struct vfio_platform_irq *irq;
> +	u16 index = desc->platform.msi_index;
> +	struct device *dev = msi_desc_to_dev(desc);
> +	struct vfio_device *device = dev_get_drvdata(dev);
> +	struct vfio_platform_device *vdev = (struct vfio_platform_device *)
> +						vfio_device_data(device);
> +
> +	for (i = 0; i < vdev->num_irqs; i++)
> +		if (vdev->irqs[i].type == VFIO_IRQ_TYPE_MSI)
> +			irq = &vdev->irqs[i];
> +
> +	irq->ctx[index].msg.address_lo = msg->address_lo;
> +	irq->ctx[index].msg.address_hi = msg->address_hi;
> +	irq->ctx[index].msg.data = msg->data;
> +}
> +
> +static int vfio_msi_enable(struct vfio_platform_device *vdev,
> +			   struct vfio_platform_irq *irq, int nvec)
> +{
> +	int ret;
> +	int msi_idx = 0;
> +	struct msi_desc *desc;
> +	struct device *dev = vdev->device;
> +
> +	irq->ctx = kcalloc(nvec, sizeof(struct vfio_irq_ctx), GFP_KERNEL);
> +	if (!irq->ctx)
> +		return -ENOMEM;
> +
> +	/* Allocate platform MSIs */
> +	ret = platform_msi_domain_alloc_irqs(dev, nvec, msi_write);
> +	if (ret < 0) {
> +		kfree(irq->ctx);
> +		return ret;
> +	}
> +
> +	for_each_msi_entry(desc, dev) {
> +		irq->ctx[msi_idx].hwirq = desc->irq;
> +		msi_idx++;
> +	}
> +
> +	irq->num_ctx = nvec;
> +	irq->config_msi = 1;
> +
> +	return 0;
> +}
> +
> +static int vfio_msi_set_vector_signal(struct vfio_platform_irq *irq,
> +				      int vector, int fd)
> +{
> +	struct eventfd_ctx *trigger;
> +	int irq_num, ret;
> +
> +	if (vector < 0 || vector >= irq->num_ctx)
> +		return -EINVAL;
> +
> +	irq_num = irq->ctx[vector].hwirq;
> +
> +	if (irq->ctx[vector].trigger) {
> +		free_irq(irq_num, irq->ctx[vector].trigger);
> +		kfree(irq->ctx[vector].name);
> +		eventfd_ctx_put(irq->ctx[vector].trigger);
> +		irq->ctx[vector].trigger = NULL;
> +	}
> +
> +	if (fd < 0)
> +		return 0;
> +
> +	irq->ctx[vector].name = kasprintf(GFP_KERNEL,
> +					  "vfio-msi[%d]", vector);
> +	if (!irq->ctx[vector].name)
> +		return -ENOMEM;
> +
> +	trigger = eventfd_ctx_fdget(fd);
> +	if (IS_ERR(trigger)) {
> +		kfree(irq->ctx[vector].name);
> +		return PTR_ERR(trigger);
> +	}
> +
> +	ret = request_irq(irq_num, vfio_msihandler, 0,
> +			  irq->ctx[vector].name, trigger);
> +	if (ret) {
> +		kfree(irq->ctx[vector].name);
> +		eventfd_ctx_put(trigger);
> +		return ret;
> +	}
> +
> +	irq->ctx[vector].trigger = trigger;
> +
> +	return 0;
> +}
> +
> +static int vfio_msi_set_block(struct vfio_platform_irq *irq, unsigned int start,
> +			      unsigned int count, int32_t *fds)
> +{
> +	int i, j, ret = 0;
> +
> +	if (start >= irq->num_ctx || start + count > irq->num_ctx)
> +		return -EINVAL;
> +
> +	for (i = 0, j = start; i < count && !ret; i++, j++) {
> +		int fd = fds ? fds[i] : -1;
> +
> +		ret = vfio_msi_set_vector_signal(irq, j, fd);
> +	}
> +
> +	if (ret) {
> +		for (--j; j >= (int)start; j--)
> +			vfio_msi_set_vector_signal(irq, j, -1);
> +	}
> +
> +	return ret;
> +}
> +
> +static void vfio_msi_disable(struct vfio_platform_device *vdev,
> +			     struct vfio_platform_irq *irq)
> +{
> +	struct device *dev = vdev->device;
> +
> +	vfio_msi_set_block(irq, 0, irq->num_ctx, NULL);
> +
> +	platform_msi_domain_free_irqs(dev);
> +
> +	irq->config_msi = 0;
> +	irq->num_ctx = 0;
> +
> +	kfree(irq->ctx);
> +}
> +
> +static int vfio_set_msi_trigger(struct vfio_platform_device *vdev,
> +				unsigned int index, unsigned int start,
> +				unsigned int count, uint32_t flags, void *data)
> +{
> +	int i;
> +	struct vfio_platform_irq *irq = &vdev->irqs[index];
> +
> +	if (start + count > irq->count)
> +		return -EINVAL;
> +
> +	if (!count && (flags & VFIO_IRQ_SET_DATA_NONE)) {
> +		vfio_msi_disable(vdev, irq);
> +		return 0;
> +	}
> +
> +	if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
> +		s32 *fds = data;
> +		int ret;
> +
> +		if (irq->config_msi)
> +			return vfio_msi_set_block(irq, start, count,
> +						  fds);
> +		ret = vfio_msi_enable(vdev, irq, start + count);
> +		if (ret)
> +			return ret;
> +
> +		ret = vfio_msi_set_block(irq, start, count, fds);
> +		if (ret)
> +			vfio_msi_disable(vdev, irq);
> +
> +		return ret;
> +	}
> +
> +	for (i = start; i < start + count; i++) {
> +		if (!irq->ctx[i].trigger)
> +			continue;
> +		if (flags & VFIO_IRQ_SET_DATA_NONE) {
> +			eventfd_signal(irq->ctx[i].trigger, 1);
> +		} else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
> +			u8 *bools = data;
> +
> +			if (bools[i - start])
> +				eventfd_signal(irq->ctx[i].trigger, 1);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
>  				 uint32_t flags, unsigned index, unsigned start,
>  				 unsigned count, void *data)
> @@ -261,16 +452,29 @@ int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
>  		    unsigned start, unsigned count, uint32_t flags,
>  		    void *data) = NULL;
>  
> -	switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) {
> -	case VFIO_IRQ_SET_ACTION_MASK:
> -		func = vfio_platform_set_irq_mask;
> -		break;
> -	case VFIO_IRQ_SET_ACTION_UNMASK:
> -		func = vfio_platform_set_irq_unmask;
> -		break;
> -	case VFIO_IRQ_SET_ACTION_TRIGGER:
> -		func = vfio_platform_set_irq_trigger;
> -		break;
> +	struct vfio_platform_irq *irq = &vdev->irqs[index];
> +
> +	if (irq->type == VFIO_IRQ_TYPE_MSI) {
> +		switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) {
> +		case VFIO_IRQ_SET_ACTION_MASK:
> +		case VFIO_IRQ_SET_ACTION_UNMASK:
> +			break;
> +		case VFIO_IRQ_SET_ACTION_TRIGGER:
> +			func = vfio_set_msi_trigger;
> +			break;
> +		}
> +	} else {
> +		switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) {
> +		case VFIO_IRQ_SET_ACTION_MASK:
> +			func = vfio_platform_set_irq_mask;
> +			break;
> +		case VFIO_IRQ_SET_ACTION_UNMASK:
> +			func = vfio_platform_set_irq_unmask;
> +			break;
> +		case VFIO_IRQ_SET_ACTION_TRIGGER:
> +			func = vfio_platform_set_irq_trigger;
> +			break;
> +		}
>  	}
>  
>  	if (!func)
> @@ -281,12 +485,21 @@ int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
>  
>  int vfio_platform_irq_init(struct vfio_platform_device *vdev)
>  {
> -	int cnt = 0, i;
> +	int i;
> +	int cnt = 0;
> +	int num_irqs;
> +	int msi_cnt = 0;
>  
>  	while (vdev->get_irq(vdev, cnt) >= 0)
>  		cnt++;
>  
> -	vdev->irqs = kcalloc(cnt, sizeof(struct vfio_platform_irq), GFP_KERNEL);
> +	if (vdev->of_get_msi) {
> +		msi_cnt = vdev->of_get_msi(vdev);
> +		num_irqs++;
> +	}
> +
> +	vdev->irqs = kcalloc(num_irqs, sizeof(struct vfio_platform_irq),
> +			     GFP_KERNEL);
>  	if (!vdev->irqs)
>  		return -ENOMEM;
>  
> @@ -309,7 +522,19 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
>  		vdev->irqs[i].masked = false;
>  	}
>  
> -	vdev->num_irqs = cnt;
> +	/*
> +	 * MSI block is added at last index and it is an ext irq
> +	 */
> +	if (msi_cnt > 0) {
> +		vdev->irqs[i].flags = VFIO_IRQ_INFO_EVENTFD;
> +		vdev->irqs[i].count = msi_cnt;
> +		vdev->irqs[i].hwirq = 0;
> +		vdev->irqs[i].masked = false;
> +		vdev->irqs[i].type = VFIO_IRQ_TYPE_MSI;
> +		vdev->num_ext_irqs = 1;
> +	}
> +
> +	vdev->num_irqs = num_irqs;
>  
>  	return 0;
>  err:
> @@ -321,8 +546,13 @@ void vfio_platform_irq_cleanup(struct vfio_platform_device *vdev)
>  {
>  	int i;
>  
> -	for (i = 0; i < vdev->num_irqs; i++)
> -		vfio_set_trigger(vdev, i, -1, NULL);
> +	for (i = 0; i < vdev->num_irqs; i++) {
> +		if (vdev->irqs[i].type == VFIO_IRQ_TYPE_MSI)
> +			vfio_set_msi_trigger(vdev, i, 0, 0,
> +					     VFIO_IRQ_SET_DATA_NONE, NULL);
> +		else
> +			vfio_set_trigger(vdev, i, -1, NULL);
> +	}
>  
>  	vdev->num_irqs = 0;
>  	kfree(vdev->irqs);
> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> index 289089910643..1307feddda21 100644
> --- a/drivers/vfio/platform/vfio_platform_private.h
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -9,6 +9,7 @@
>  
>  #include <linux/types.h>
>  #include <linux/interrupt.h>
> +#include <linux/msi.h>
>  
>  #define VFIO_PLATFORM_OFFSET_SHIFT   40
>  #define VFIO_PLATFORM_OFFSET_MASK (((u64)(1) << VFIO_PLATFORM_OFFSET_SHIFT) - 1)
> @@ -19,9 +20,21 @@
>  #define VFIO_PLATFORM_INDEX_TO_OFFSET(index)	\
>  	((u64)(index) << VFIO_PLATFORM_OFFSET_SHIFT)
>  
> +/* IRQ index for MSI in ext IRQs */
> +#define VFIO_EXT_IRQ_MSI	0
> +
> +struct vfio_irq_ctx {
> +	int			hwirq;
> +	char			*name;
> +	struct msi_msg		msg;
> +	struct eventfd_ctx	*trigger;
> +};
> +
>  struct vfio_platform_irq {
>  	u32			flags;
>  	u32			count;
> +	int			num_ctx;
> +	struct vfio_irq_ctx	*ctx;
>  	int			hwirq;
>  	char			*name;
>  	struct eventfd_ctx	*trigger;
> @@ -29,6 +42,11 @@ struct vfio_platform_irq {
>  	spinlock_t		lock;
>  	struct virqfd		*unmask;
>  	struct virqfd		*mask;
> +
> +	/* for extended irqs */
> +	u32			type;
> +	u32			subtype;
> +	int			config_msi;
>  };
>  
>  struct vfio_platform_region {
> @@ -46,12 +64,14 @@ struct vfio_platform_device {
>  	u32				num_regions;
>  	struct vfio_platform_irq	*irqs;
>  	u32				num_irqs;
> +	int				num_ext_irqs;
>  	int				refcnt;
>  	struct mutex			igate;
>  	struct module			*parent_module;
>  	const char			*compat;
>  	const char			*acpihid;
>  	struct module			*reset_module;
> +	struct module			*msi_module;
>  	struct device			*device;
>  
>  	/*
> @@ -65,11 +85,13 @@ struct vfio_platform_device {
>  		(*get_resource)(struct vfio_platform_device *vdev, int i);
>  	int	(*get_irq)(struct vfio_platform_device *vdev, int i);
>  	int	(*of_reset)(struct vfio_platform_device *vdev);
> +	u32	(*of_get_msi)(struct vfio_platform_device *vdev);
>  
>  	bool				reset_required;
>  };
>  
>  typedef int (*vfio_platform_reset_fn_t)(struct vfio_platform_device *vdev);
> +typedef u32 (*vfio_platform_get_msi_fn_t)(struct vfio_platform_device *vdev);
>  
>  struct vfio_platform_reset_node {
>  	struct list_head link;
> @@ -78,6 +100,13 @@ struct vfio_platform_reset_node {
>  	vfio_platform_reset_fn_t of_reset;
>  };
>  
> +struct vfio_platform_msi_node {
> +	struct list_head link;
> +	char *compat;
> +	struct module *owner;
> +	vfio_platform_get_msi_fn_t of_get_msi;
> +};
> +
>  extern int vfio_platform_probe_common(struct vfio_platform_device *vdev,
>  				      struct device *dev);
>  extern struct vfio_platform_device *vfio_platform_remove_common
> @@ -94,6 +123,9 @@ extern int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
>  extern void __vfio_platform_register_reset(struct vfio_platform_reset_node *n);
>  extern void vfio_platform_unregister_reset(const char *compat,
>  					   vfio_platform_reset_fn_t fn);
> +void __vfio_platform_register_msi(struct vfio_platform_msi_node *n);
> +void vfio_platform_unregister_msi(const char *compat);
> +
>  #define vfio_platform_register_reset(__compat, __reset)		\
>  static struct vfio_platform_reset_node __reset ## _node = {	\
>  	.owner = THIS_MODULE,					\
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index d1812777139f..53a7ff2b524e 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -697,11 +697,55 @@ struct vfio_irq_info {
>  #define VFIO_IRQ_INFO_MASKABLE		(1 << 1)
>  #define VFIO_IRQ_INFO_AUTOMASKED	(1 << 2)
>  #define VFIO_IRQ_INFO_NORESIZE		(1 << 3)
> +#define VFIO_IRQ_INFO_FLAG_CAPS		(1 << 4) /* Info supports caps */
>  	__u32	index;		/* IRQ index */
>  	__u32	count;		/* Number of IRQs within this index */
> +	__u32	cap_offset;	/* Offset within info struct of first cap */
>  };
>  #define VFIO_DEVICE_GET_IRQ_INFO	_IO(VFIO_TYPE, VFIO_BASE + 9)
>  
> +/*
> + * The irq type capability allows IRQs unique to a specific device or
> + * class of devices to be exposed.
> + *
> + * The structures below define version 1 of this capability.
> + */
> +#define VFIO_IRQ_INFO_CAP_TYPE		3
> +
> +struct vfio_irq_info_cap_type {
> +	struct vfio_info_cap_header header;
> +	__u32 type;     /* global per bus driver */
> +	__u32 subtype;  /* type specific */
> +};
> +
> +/*
> + * List of IRQ types, global per bus driver.
> + * If you introduce a new type, please add it here.
> + */
> +
> +/* Non PCI devices having MSI(s) support */
> +#define VFIO_IRQ_TYPE_MSI		(1)
> +
> +/*
> + * The msi capability allows the user to use the msi msg to
> + * configure the iova for the msi configuration.
> + * The structures below define version 1 of this capability.
> + */
> +#define VFIO_IRQ_INFO_CAP_MSI_DESCS	4
> +
> +struct vfio_irq_msi_msg {
> +	__u32	addr_lo;
> +	__u32	addr_hi;
> +	__u32	data;
> +};
> +
> +struct vfio_irq_info_cap_msi {
> +	struct vfio_info_cap_header header;
> +	__u32	nr_msgs;
> +	__u32	reserved;
> +	struct vfio_irq_msi_msg msgs[];
> +};
> +
>  /**
>   * VFIO_DEVICE_SET_IRQS - _IOW(VFIO_TYPE, VFIO_BASE + 10, struct vfio_irq_set)
>   *
>