[RFC, v0 1/3] vfio/platform: add support for msi

From: Vikas Gupta
Date: Thu Nov 05 2020 - 01:05:45 EST

MSI support for platform devices.

Signed-off-by: Vikas Gupta <vikas.gupta@xxxxxxxxxxxx>
---
drivers/vfio/platform/vfio_platform_common.c | 84 ++++++-
drivers/vfio/platform/vfio_platform_irq.c | 235 +++++++++++++++++-
drivers/vfio/platform/vfio_platform_private.h | 23 ++
include/uapi/linux/vfio.h | 1 +
4 files changed, 329 insertions(+), 14 deletions(-)

diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index c0771a9567fb..c713f4e4c552 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -26,6 +26,10 @@
#define VFIO_PLATFORM_IS_ACPI(vdev) ((vdev)->acpihid != NULL)

static LIST_HEAD(reset_list);
+
+/* devices having MSI support */
+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 +51,26 @@ 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;
+ vdev->of_msi_write = iter->of_msi_write;
+ 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)
{
@@ -110,6 +134,11 @@ static bool vfio_platform_has_reset(struct vfio_platform_device *vdev)
return vdev->of_reset ? true : false;
}

+static bool vfio_platform_has_msi(struct vfio_platform_device *vdev)
+{
+ return vdev->of_get_msi ? true : false;
+}
+
static int vfio_platform_get_reset(struct vfio_platform_device *vdev)
{
if (VFIO_PLATFORM_IS_ACPI(vdev))
@@ -126,6 +155,19 @@ 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 +177,12 @@ 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;
@@ -313,6 +361,10 @@ static long vfio_platform_ioctl(void *device_data,

if (vfio_platform_has_reset(vdev))
vdev->flags |= VFIO_DEVICE_FLAGS_RESET;
+
+ if (vfio_platform_has_msi(vdev))
+ vdev->flags |= VFIO_DEVICE_FLAGS_MSI;
+
info.flags = vdev->flags;
info.num_regions = vdev->num_regions;
info.num_irqs = vdev->num_irqs;
@@ -679,11 +731,15 @@ 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");
+
group = vfio_iommu_group_get(dev);
if (!group) {
dev_err(dev, "No IOMMU group for device %s\n", vdev->name);
ret = -EINVAL;
- goto put_reset;
+ goto put_msi;
}

ret = vfio_add_group_dev(dev, &vfio_platform_ops, vdev);
@@ -697,6 +753,8 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,

put_iommu:
vfio_iommu_group_put(group, dev);
+put_msi:
+ vfio_platform_put_msi(vdev);
put_reset:
vfio_platform_put_reset(vdev);
return ret;
@@ -745,6 +803,30 @@ 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..14b544c3aa42 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 +255,176 @@ 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, int nvec)
+{
+ int ret;
+ int msi_idx = 0;
+ struct msi_desc *desc;
+ struct device *dev = vdev->device;
+ u32 msi_off = vdev->num_irqs - vdev->num_msis;
+
+ /* Allocate platform MSIs */
+ ret = platform_msi_domain_alloc_irqs(dev, nvec, msi_write);
+ if (ret < 0)
+ return ret;
+
+ for_each_msi_entry(desc, dev) {
+ vdev->irqs[msi_off + msi_idx].hwirq = desc->irq;
+ msi_idx++;
+ }
+
+ vdev->num_msis = nvec;
+ vdev->config_msi = 1;
+
+ return 0;
+}
+
+static int vfio_msi_set_vector_signal(struct vfio_platform_device *vdev,
+ int vector, int fd)
+{
+ struct eventfd_ctx *trigger;
+ int irq, ret;
+ u32 msi_off = vdev->num_irqs - vdev->num_msis;
+
+ if (vector < 0 || vector >= vdev->num_msis)
+ return -EINVAL;
+
+ irq = vdev->irqs[msi_off + vector].hwirq;
+
+ if (vdev->irqs[vector].trigger) {
+ free_irq(irq, vdev->irqs[vector].trigger);
+ kfree(vdev->irqs[vector].name);
+ eventfd_ctx_put(vdev->irqs[vector].trigger);
+ vdev->irqs[vector].trigger = NULL;
+ }
+
+ if (fd < 0)
+ return 0;
+
+ vdev->irqs[vector].name = kasprintf(GFP_KERNEL,
+ "vfio-msi[%d]", vector);
+ if (!vdev->irqs[vector].name)
+ return -ENOMEM;
+
+ trigger = eventfd_ctx_fdget(fd);
+ if (IS_ERR(trigger)) {
+ kfree(vdev->irqs[vector].name);
+ return PTR_ERR(trigger);
+ }
+
+ ret = request_irq(irq, vfio_msihandler, 0,
+ vdev->irqs[vector].name, trigger);
+ if (ret) {
+ kfree(vdev->irqs[vector].name);
+ eventfd_ctx_put(trigger);
+ return ret;
+ }
+
+ vdev->irqs[vector].trigger = trigger;
+
+ return 0;
+}
+
+static int vfio_msi_set_block(struct vfio_platform_device *vdev, unsigned int start,
+ unsigned int count, int32_t *fds)
+{
+ int i, j, ret = 0;
+
+ if (start >= vdev->num_msis || start + count > vdev->num_msis)
+ return -EINVAL;
+
+ for (i = 0, j = start; i < count && !ret; i++, j++) {
+ int fd = fds ? fds[i] : -1;
+
+ ret = vfio_msi_set_vector_signal(vdev, j, fd);
+ }
+
+ if (ret) {
+ for (--j; j >= (int)start; j--)
+ vfio_msi_set_vector_signal(vdev, j, -1);
+ }
+
+ return ret;
+}
+
+static void vfio_msi_disable(struct vfio_platform_device *vdev)
+{
+ struct device *dev = vdev->device;
+
+ vfio_msi_set_block(vdev, 0, vdev->num_msis, NULL);
+ platform_msi_domain_free_irqs(dev);
+
+ vdev->config_msi = 0;
+ vdev->num_msis = 0;
+}
+
+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;
+
+ if (start + count > vdev->num_msis)
+ return -EINVAL;
+
+ if (!count && (flags & VFIO_IRQ_SET_DATA_NONE)) {
+ vfio_msi_disable(vdev);
+ return 0;
+ }
+
+ if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
+ s32 *fds = data;
+ int ret;
+
+ if (vdev->config_msi)
+ return vfio_msi_set_block(vdev, start, count,
+ fds);
+ ret = vfio_msi_enable(vdev, start + count);
+ if (ret)
+ return ret;
+
+ ret = vfio_msi_set_block(vdev, start, count, fds);
+ if (ret)
+ vfio_msi_disable(vdev);
+
+ return ret;
+ }
+
+ for (i = start; i < start + count; i++) {
+ if (!vdev->irqs[i].trigger)
+ continue;
+ if (flags & VFIO_IRQ_SET_DATA_NONE) {
+ eventfd_signal(vdev->irqs[i].trigger, 1);
+ } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
+ u8 *bools = data;
+
+ if (bools[i - start])
+ eventfd_signal(vdev->irqs[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 +433,29 @@ 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->is_msi) {
+ 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;
+ }
+ } else {
+ 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;
+ }
}

if (!func)
@@ -282,11 +467,17 @@ 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 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);
+ vdev->num_msis = msi_cnt;
+
+ vdev->irqs = kcalloc(cnt + msi_cnt, sizeof(struct vfio_platform_irq),
+ GFP_KERNEL);
if (!vdev->irqs)
return -ENOMEM;

@@ -309,7 +500,18 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
vdev->irqs[i].masked = false;
}

- vdev->num_irqs = cnt;
+ for (i = cnt; i < msi_cnt + cnt; i++) {
+ spin_lock_init(&vdev->irqs[i].lock);
+
+ vdev->irqs[i].flags = VFIO_IRQ_INFO_EVENTFD;
+
+ vdev->irqs[i].count = 1;
+ vdev->irqs[i].hwirq = 0;
+ vdev->irqs[i].masked = false;
+ vdev->irqs[i].is_msi = true;
+ }
+
+ vdev->num_irqs = cnt + msi_cnt;

return 0;
err:
@@ -320,10 +522,17 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
void vfio_platform_irq_cleanup(struct vfio_platform_device *vdev)
{
int i;
+ int non_msi_cnt = vdev->num_irqs - vdev->num_msis;

- for (i = 0; i < vdev->num_irqs; i++)
+ for (i = 0; i < non_msi_cnt; i++)
vfio_set_trigger(vdev, i, -1, NULL);

+ if (vdev->num_msis) {
+ vfio_set_msi_trigger(vdev, 0, 0, 0,
+ VFIO_IRQ_SET_DATA_NONE, NULL);
+ vdev->num_msis = 0;
+ }
+
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..2aea445e1071 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)
@@ -26,6 +27,7 @@ struct vfio_platform_irq {
char *name;
struct eventfd_ctx *trigger;
bool masked;
+ bool is_msi;
spinlock_t lock;
struct virqfd *unmask;
struct virqfd *mask;
@@ -46,13 +48,16 @@ struct vfio_platform_device {
u32 num_regions;
struct vfio_platform_irq *irqs;
u32 num_irqs;
+ u32 num_msis;
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;
+ int config_msi;

/*
* These fields should be filled by the bus specific binder
@@ -65,11 +70,19 @@ 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);
+ int (*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 int (*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;
@@ -78,6 +91,14 @@ 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;
+ vfio_platform_msi_write_fn_t of_msi_write;
+};
+
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 +115,8 @@ 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 2f313a238a8f..aab051e8338d 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -203,6 +203,7 @@ struct vfio_device_info {
#define VFIO_DEVICE_FLAGS_AP (1 << 5) /* vfio-ap device */
#define VFIO_DEVICE_FLAGS_FSL_MC (1 << 6) /* vfio-fsl-mc device */
#define VFIO_DEVICE_FLAGS_CAPS (1 << 7) /* Info supports caps */
+#define VFIO_DEVICE_FLAGS_MSI (1 << 8) /* Device supports msi */
__u32 num_regions; /* Max region index + 1 */
__u32 num_irqs; /* Max IRQ index + 1 */
__u32 cap_offset; /* Offset within info struct of first cap */
--
2.17.1

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