Re: [PATCH v6 05/20] vfio: mdev: common lib code for setting up Interrupt Message Store

Jason Gunthorpe
2021-05-24T00:03:04Z

On Fri, May 21, 2021 at 05:19:36PM -0700, Dave Jiang wrote:
> Add common helper code to setup IMS once the MSI domain has been
> setup by the device driver. The main helper function is
> mdev_ims_set_msix_trigger() that is called by the VFIO ioctl
> VFIO_DEVICE_SET_IRQS. The function deals with the setup and
> teardown of emulated and IMS backed eventfd that gets exported
> to the guest kernel via VFIO as MSIX vectors.
>
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
> drivers/vfio/mdev/Kconfig | 12 ++
> drivers/vfio/mdev/Makefile | 3
> drivers/vfio/mdev/mdev_irqs.c | 318 +++++++++++++++++++++++++++++++++++++++++
> include/linux/mdev.h | 51 +++++++
> 4 files changed, 384 insertions(+)
> create mode 100644 drivers/vfio/mdev/mdev_irqs.c

IMS is not mdev specific, do not entangle it with mdev code. This
should be generic VFIO stuff.

> +static int mdev_msix_set_vector_signal(struct mdev_irq *mdev_irq, int vector, int fd)
> +{
> + int rc, irq;
> + struct mdev_device *mdev = irq_to_mdev(mdev_irq);
> + struct mdev_irq_entry *entry;
> + struct device *dev = &mdev->dev;
> + struct eventfd_ctx *trigger;
> + char *name;
> + bool pasid_en;
> + u32 auxval;
> +
> + if (vector < 0 || vector >= mdev_irq->num)
> + return -EINVAL;
> +
> + entry = &mdev_irq->irq_entries[vector];
> +
> + if (entry->ims)
> + irq = dev_msi_irq_vector(dev, entry->ims_id);
> + else
> + irq = 0;
> +
> + pasid_en = mdev_irq->pasid != INVALID_IOASID ? true : false;
> +
> + /* IMS and invalid pasid is not a valid configuration */
> + if (entry->ims && !pasid_en)
> + return -EINVAL;
> +
> + if (entry->trigger) {
> + if (irq) {
> + irq_bypass_unregister_producer(&entry->producer);
> + free_irq(irq, entry->trigger);
> + if (pasid_en) {
> + auxval = ims_ctrl_pasid_aux(0, false);
> + irq_set_auxdata(irq, IMS_AUXDATA_CONTROL_WORD, auxval);
> + }
> + }
> + kfree(entry->name);
> + eventfd_ctx_put(entry->trigger);
> + entry->trigger = NULL;
> + }
> +
> + if (fd < 0)
> + return 0;
> +
> + name = kasprintf(GFP_KERNEL, "vfio-mdev-irq[%d](%s)", vector, dev_name(dev));
> + if (!name)
> + return -ENOMEM;
> +
> + trigger = eventfd_ctx_fdget(fd);
> + if (IS_ERR(trigger)) {
> + kfree(name);
> + return PTR_ERR(trigger);
> + }
> +
> + entry->name = name;
> + entry->trigger = trigger;
> +
> + if (!irq)
> + return 0;
> +
> + if (pasid_en) {
> + auxval = ims_ctrl_pasid_aux(mdev_irq->pasid, true);
> + rc = irq_set_auxdata(irq, IMS_AUXDATA_CONTROL_WORD, auxval);
> + if (rc < 0)
> + goto err;

Why is anything to do with PASID here? Something has gone wrong with
the layers I suspect..

Oh yes. drivers/irqchip/irq-ims-msi.c is dxd specific and shouldn't be
pretending to be common code.

The protocol to stuff the pasid and other stuff into the auxdata is
also compeltely idxd specific and is just a hacky way to communicate
from this code to the IDXD irq-chip.

So this doesn't belong here either. Pass in the auxdata from the idxd
code and I'd rename the irq-ims-msi to irq-ims-idxd

> +static int mdev_msix_enable(struct mdev_irq *mdev_irq, int nvec)
> +{
> + struct mdev_device *mdev = irq_to_mdev(mdev_irq);
> + struct device *dev;
> + int rc;
> +
> + if (nvec != mdev_irq->num)
> + return -EINVAL;
> +
> + if (mdev_irq->ims_num) {
> + dev = &mdev->dev;
> + rc = msi_domain_alloc_irqs(dev_get_msi_domain(dev), dev, mdev_irq->ims_num);

Huh? The PCI device should be the only device touching IRQ stuff. I'm
nervous to see you mix in the mdev struct device into this function.

Isn't the msi_domain just idxd->ims_domain?

Jason