[RFC v4 1/3] vfio/platform: add support for msi

[Vikas Gupta <vikas.gupta@broadcom.com>]

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MSI support for platform devices. MSI is added
as a single 'index' with 'count' as the number of
MSI(s) supported by the devices.

Signed-off-by: Vikas Gupta <vikas.gupta@broadcom.com>
---
 drivers/vfio/platform/Kconfig                 |   1 +
 drivers/vfio/platform/vfio_platform_common.c  |  95 ++++++-
 drivers/vfio/platform/vfio_platform_irq.c     | 253 ++++++++++++++++--
 drivers/vfio/platform/vfio_platform_private.h |  29 ++
 include/uapi/linux/vfio.h                     |  24 ++
 5 files changed, 373 insertions(+), 29 deletions(-)

diff --git a/drivers/vfio/platform/Kconfig b/drivers/vfio/platform/Kconfig
index dc1a3c44f2c6..d4bbc9f27763 100644
--- a/drivers/vfio/platform/Kconfig
+++ b/drivers/vfio/platform/Kconfig
@@ -3,6 +3,7 @@ config VFIO_PLATFORM
 	tristate "VFIO support for platform devices"
 	depends on VFIO && EVENTFD && (ARM || ARM64)
 	select VFIO_VIRQFD
+	select GENERIC_MSI_IRQ_DOMAIN
 	help
 	  Support for platform devices with VFIO. This is required to make
 	  use of platform devices present on the system using the VFIO
diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index fb4b385191f2..f2b1f0c3bfcc 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"
 
@@ -28,23 +29,22 @@
 static LIST_HEAD(reset_list);
 static DEFINE_MUTEX(driver_lock);
 
-static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
-					struct module **module)
+static void vfio_platform_lookup_reset(const char *compat,
+				       struct module **module,
+				       struct vfio_platform_reset_node **node)
 {
 	struct vfio_platform_reset_node *iter;
-	vfio_platform_reset_fn_t reset_fn = NULL;
 
 	mutex_lock(&driver_lock);
 	list_for_each_entry(iter, &reset_list, link) {
 		if (!strcmp(iter->compat, compat) &&
 			try_module_get(iter->owner)) {
 			*module = iter->owner;
-			reset_fn = iter->of_reset;
+			*node = iter;
 			break;
 		}
 	}
 	mutex_unlock(&driver_lock);
-	return reset_fn;
 }
 
 static int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
@@ -112,15 +112,23 @@ static bool vfio_platform_has_reset(struct vfio_platform_device *vdev)
 
 static int vfio_platform_get_reset(struct vfio_platform_device *vdev)
 {
+	struct vfio_platform_reset_node *node = NULL;
+
 	if (VFIO_PLATFORM_IS_ACPI(vdev))
 		return vfio_platform_acpi_has_reset(vdev) ? 0 : -ENOENT;
 
-	vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
-						    &vdev->reset_module);
-	if (!vdev->of_reset) {
+	vfio_platform_lookup_reset(vdev->compat, &vdev->reset_module,
+				   &node);
+	if (!node) {
 		request_module("vfio-reset:%s", vdev->compat);
-		vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
-							&vdev->reset_module);
+		vfio_platform_lookup_reset(vdev->compat, &vdev->reset_module,
+					   &node);
+	}
+
+	if (node) {
+		vdev->of_reset = node->of_reset;
+		vdev->of_get_msi = node->of_get_msi;
+		vdev->of_msi_write = node->of_msi_write;
 	}
 
 	return vdev->of_reset ? 0 : -ENOENT;
@@ -343,9 +351,16 @@ 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 };
+		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 +370,53 @@ 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;
+			int ret;
+
+			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;
+		}
+
+		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(caps.buf);
+					return -EFAULT;
+				}
+				info.cap_offset = sizeof(info);
+			}
+
+			kfree(caps.buf);
+		}
 
 		return copy_to_user((void __user *)arg, &info, minsz) ?
 			-EFAULT : 0;
@@ -365,6 +425,7 @@ 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 +433,14 @@ 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;
 
diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
index c5b09ec0a3c9..db60240d27ca 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 +255,186 @@ 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)
+{
+	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);
+
+	vdev->of_msi_write(vdev, desc, msg);
+}
+
+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 +443,29 @@ 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 +476,23 @@ 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 = 0;
+	int msi_cnt = 0;
 
 	while (vdev->get_irq(vdev, cnt) >= 0)
 		cnt++;
 
-	vdev->irqs = kcalloc(cnt, sizeof(struct vfio_platform_irq), GFP_KERNEL);
+	num_irqs = cnt;
+
+	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 +515,19 @@ 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 +539,13 @@ 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..b8dd892aec53 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 {
@@ -46,6 +64,7 @@ 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;
@@ -65,17 +84,27 @@ 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);
+	void	(*of_msi_write)(struct vfio_platform_device *vdev,
+				struct msi_desc *desc,
+				struct msi_msg *msg);
 
 	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);
+typedef void (*vfio_platform_msi_write_fn_t)(struct vfio_platform_device *vdev,
+					     struct msi_desc *desc,
+					     struct msi_msg *msg);
 
 struct vfio_platform_reset_node {
 	struct list_head link;
 	char *compat;
 	struct module *owner;
 	vfio_platform_reset_fn_t of_reset;
+	vfio_platform_get_msi_fn_t of_get_msi;
+	vfio_platform_msi_write_fn_t of_msi_write;
 };
 
 extern int vfio_platform_probe_common(struct vfio_platform_device *vdev,
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index d1812777139f..8e2c0131781d 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -697,11 +697,35 @@ 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)
+
 /**
  * VFIO_DEVICE_SET_IRQS - _IOW(VFIO_TYPE, VFIO_BASE + 10, struct vfio_irq_set)
  *
-- 
2.17.1


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