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

From: Vikas Gupta
Date: Fri Jan 29 2021 - 12:26:05 EST

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@xxxxxxxxxxxx>
---
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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