Re: [RFC v2 1/1] vfio/platform: add support for msi

From: Vikas Gupta
Date: Thu Dec 03 2020 - 09:51:39 EST

Hi Eric,

On Wed, Dec 2, 2020 at 8:14 PM Auger Eric <eric.auger@xxxxxxxxxx> wrote:
>
> Hi Vikas,
>
> On 11/24/20 5:16 PM, Vikas Gupta wrote:
> > MSI support for platform devices.
> >
> > Signed-off-by: Vikas Gupta <vikas.gupta@xxxxxxxxxxxx>
> > ---
> > drivers/vfio/platform/vfio_platform_common.c | 99 ++++++-
> > drivers/vfio/platform/vfio_platform_irq.c | 260 +++++++++++++++++-
> > drivers/vfio/platform/vfio_platform_private.h | 16 ++
> > include/uapi/linux/vfio.h | 43 +++
> > 4 files changed, 401 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> > index c0771a9567fb..b0bfc0f4ee1f 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"
> >
> > @@ -344,9 +345,16 @@ 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 };
> > + struct vfio_irq_info_cap_msi *msi_info = NULL;
> > + unsigned long capsz;
> > + int ext_irq_index = vdev->num_irqs - vdev->num_ext_irqs;
> >
> > 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;
> >
> > @@ -356,9 +364,89 @@ static long vfio_platform_ioctl(void *device_data,
> > if (info.index >= vdev->num_irqs)
> > return -EINVAL;
> >
> > + if (info.argsz >= capsz)
> > + minsz = capsz;
> > +
> > + if (info.index == ext_irq_index) {
> nit: n case we add new ext indices afterwards, I would check info.index
> - ext_irq_index against an VFIO_EXT_IRQ_MSI define.
> > + struct vfio_irq_info_cap_type cap_type = {
> > + .header.id = VFIO_IRQ_INFO_CAP_TYPE,
> > + .header.version = 1 };
> > + int i;
> > + int ret;
> > + int num_msgs;
> > + size_t msi_info_size;
> > + struct vfio_platform_irq *irq;
> nit: I think generally the opposite order (length) is chosen. This also
> would better match the existing style in this file
Ok will fix it
> > +
> > + info.index = array_index_nospec(info.index,
> > + vdev->num_irqs);
> > +
> > + irq = &vdev->irqs[info.index];
> > +
> > + info.flags = irq->flags;
> I think this can be removed given [*]
Sure.
> > + 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;
> do would want to return the cap even if !num_ctx?
If num_ctx = 0 then VFIO_IRQ_INFO_CAP_MSI_DESCS should not be written.
I`ll take care of same.
> > +
> > + 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;
> > + 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;
> > + }
> > + }
> > +
> > info.flags = vdev->irqs[info.index].flags;
> [*]
Will fix it.
> > info.count = vdev->irqs[info.index].count;
> >
> > + 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;
> >
> > @@ -366,6 +454,7 @@ 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);
> > @@ -373,8 +462,14 @@ 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..4066223e5b2e 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;
> > + struct device *dev = vdev->device;
> >
> > while (vdev->get_irq(vdev, cnt) >= 0)
> > cnt++;
> >
> > - vdev->irqs = kcalloc(cnt, sizeof(struct vfio_platform_irq), GFP_KERNEL);
> > + num_irqs = cnt;
> > +
> > + if (dev->msi_domain)
> > + 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 its an ext irq
> it is
> > + */
> > + if (dev->msi_domain) {
> > + vdev->irqs[i].flags = VFIO_IRQ_INFO_EVENTFD;
> > + vdev->irqs[i].count = NR_IRQS;
> why NR_IRQS?
Since different devices can have different numbers of MSI(s) so we
need to initialize with max possible values. Can you please suggest if
this value does not seem appropriate?
> > + 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..7bbb05988705 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 +20,18 @@
> > #define VFIO_PLATFORM_INDEX_TO_OFFSET(index) \
> > ((u64)(index) << VFIO_PLATFORM_OFFSET_SHIFT)
> >
> > +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 +39,11 @@ 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 +61,7 @@ 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;
> > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> > index 2f313a238a8f..598d1c944283 100644
> > --- a/include/uapi/linux/vfio.h
> > +++ b/include/uapi/linux/vfio.h
> > @@ -697,11 +697,54 @@ 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;
> I think you should align a __u32 reserved field to have a 64b alignment
Sure.
> > + struct vfio_irq_msi_msg msgs[];
> Please can you clarify why this cap is needed versus your prior approach.
In the previous patch, the reset module was configuring the device
with MSI msg/data now since the module is not available, user space
needs to have this data.
With this approach userspace just needs the pairs <msg and ctx >
associated with the MSI(s) and it can choose to configure the MSI(s)
sources accordingly.
Let me know if this approach does not look appropriate.

Thanks,
Vikas
> > +};
> > +
> > /**
> > * VFIO_DEVICE_SET_IRQS - _IOW(VFIO_TYPE, VFIO_BASE + 10, struct vfio_irq_set)
> > *
> >
> Thanks
>
> Eric
>

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