On Fri, Feb 03, 2023 at 07:04:17PM +0900, Shunsuke Mie wrote:
> Add a new library to access a virtio ring located on PCIe host memory. The
> library generates struct pci_epf_vringh that is introduced in this patch.
> The struct has a vringh member, so vringh APIs can be used to access the
> virtio ring.
>
> Signed-off-by: Shunsuke Mie <mie@xxxxxxxxxx>
> Signed-off-by: Takanari Hayama <taki@xxxxxxxxxx>
> ---
> drivers/pci/endpoint/Kconfig | 7 ++
> drivers/pci/endpoint/Makefile | 1 +
> drivers/pci/endpoint/pci-epf-virtio.c | 113 ++++++++++++++++++++++++++
> include/linux/pci-epf-virtio.h | 25 ++++++
> 4 files changed, 146 insertions(+)
> create mode 100644 drivers/pci/endpoint/pci-epf-virtio.c
> create mode 100644 include/linux/pci-epf-virtio.h
>
> diff --git a/drivers/pci/endpoint/Kconfig b/drivers/pci/endpoint/Kconfig
> index 17bbdc9bbde0..07276dcc43c8 100644
> --- a/drivers/pci/endpoint/Kconfig
> +++ b/drivers/pci/endpoint/Kconfig
> @@ -28,6 +28,13 @@ config PCI_ENDPOINT_CONFIGFS
> configure the endpoint function and used to bind the
> function with a endpoint controller.
>
> +config PCI_ENDPOINT_VIRTIO
> + tristate
> + depends on PCI_ENDPOINT
> + select VHOST_IOMEM
> + help
> + TODO update this comment
> +
> source "drivers/pci/endpoint/functions/Kconfig"
>
> endmenu
> diff --git a/drivers/pci/endpoint/Makefile b/drivers/pci/endpoint/Makefile
> index 95b2fe47e3b0..95712f0a13d1 100644
> --- a/drivers/pci/endpoint/Makefile
> +++ b/drivers/pci/endpoint/Makefile
> @@ -4,5 +4,6 @@
> #
>
> obj-$(CONFIG_PCI_ENDPOINT_CONFIGFS) += pci-ep-cfs.o
> +obj-$(CONFIG_PCI_ENDPOINT_VIRTIO) += pci-epf-virtio.o
> obj-$(CONFIG_PCI_ENDPOINT) += pci-epc-core.o pci-epf-core.o\
> pci-epc-mem.o functions/
> diff --git a/drivers/pci/endpoint/pci-epf-virtio.c b/drivers/pci/endpoint/pci-epf-virtio.c
> new file mode 100644
> index 000000000000..7134ca407a03
> --- /dev/null
> +++ b/drivers/pci/endpoint/pci-epf-virtio.c
> @@ -0,0 +1,113 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Virtio library for PCI Endpoint function
> + */
> +#include <linux/kernel.h>
> +#include <linux/pci-epf-virtio.h>
> +#include <linux/pci-epc.h>
> +#include <linux/virtio_pci.h>
> +
> +static void __iomem *epf_virtio_map_vq(struct pci_epf *epf, u32 pfn,
> + size_t size, phys_addr_t *vq_phys)
> +{
> + int err;
> + phys_addr_t vq_addr;
> + size_t vq_size;
> + void __iomem *vq_virt;
> +
> + vq_addr = (phys_addr_t)pfn << VIRTIO_PCI_QUEUE_ADDR_SHIFT;
> +
> + vq_size = vring_size(size, VIRTIO_PCI_VRING_ALIGN) + 100;
100?
Also ugh, this uses the legacy vring_size.
Did not look closely but is all this limited to legacy virtio then?
Pls make sure you code builds with #define VIRTIO_RING_NO_LEGACY.
> +
> + vq_virt = pci_epc_mem_alloc_addr(epf->epc, vq_phys, vq_size);
> + if (!vq_virt) {
> + pr_err("Failed to allocate epc memory\n");
> + return ERR_PTR(-ENOMEM);
> + }
> +
> + err = pci_epc_map_addr(epf->epc, epf->func_no, epf->vfunc_no, *vq_phys,
> + vq_addr, vq_size);
> + if (err) {
> + pr_err("Failed to map virtuqueue to local");
> + goto err_free;
> + }
> +
> + return vq_virt;
> +
> +err_free:
> + pci_epc_mem_free_addr(epf->epc, *vq_phys, vq_virt, vq_size);
> +
> + return ERR_PTR(err);
> +}
> +
> +static void epf_virtio_unmap_vq(struct pci_epf *epf, void __iomem *vq_virt,
> + phys_addr_t vq_phys, size_t size)
> +{
> + pci_epc_unmap_addr(epf->epc, epf->func_no, epf->vfunc_no, vq_phys);
> + pci_epc_mem_free_addr(epf->epc, vq_phys, vq_virt,
> + vring_size(size, VIRTIO_PCI_VRING_ALIGN));
> +}
> +
> +/**
> + * pci_epf_virtio_alloc_vringh() - allocate epf vringh from @pfn
> + * @epf: the EPF device that communicates to host virtio dirver
> + * @features: the virtio features of device
> + * @pfn: page frame number of virtqueue located on host memory. It is
> + * passed during virtqueue negotiation.
> + * @size: a length of virtqueue
> + */
> +struct pci_epf_vringh *pci_epf_virtio_alloc_vringh(struct pci_epf *epf,
> + u64 features, u32 pfn,
> + size_t size)
> +{
> + int err;
> + struct vring vring;
> + struct pci_epf_vringh *evrh;
> +
> + evrh = kmalloc(sizeof(*evrh), GFP_KERNEL);
> + if (!evrh) {
> + err = -ENOMEM;
> + goto err_unmap_vq;
> + }
> +
> + evrh->size = size;
> +
> + evrh->virt = epf_virtio_map_vq(epf, pfn, size, &evrh->phys);
> + if (IS_ERR(evrh->virt))
> + return evrh->virt;
> +
> + vring_init(&vring, size, evrh->virt, VIRTIO_PCI_VRING_ALIGN);
> +
> + err = vringh_init_iomem(&evrh->vrh, features, size, false, GFP_KERNEL,
> + vring.desc, vring.avail, vring.used);
> + if (err)
> + goto err_free_epf_vq;
> +
> + return evrh;
> +
> +err_free_epf_vq:
> + kfree(evrh);
> +
> +err_unmap_vq:
> + epf_virtio_unmap_vq(epf, evrh->virt, evrh->phys, evrh->size);
> +
> + return ERR_PTR(err);
> +}
> +EXPORT_SYMBOL_GPL(pci_epf_virtio_alloc_vringh);
> +
> +/**
> + * pci_epf_virtio_free_vringh() - release allocated epf vring
> + * @epf: the EPF device that communicates to host virtio dirver
> + * @evrh: epf vringh to free
> + */
> +void pci_epf_virtio_free_vringh(struct pci_epf *epf,
> + struct pci_epf_vringh *evrh)
> +{
> + epf_virtio_unmap_vq(epf, evrh->virt, evrh->phys, evrh->size);
> + kfree(evrh);
> +}
> +EXPORT_SYMBOL_GPL(pci_epf_virtio_free_vringh);
> +
> +MODULE_DESCRIPTION("PCI EP Virtio Library");
> +MODULE_AUTHOR("Shunsuke Mie <mie@xxxxxxxxxx>");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/pci-epf-virtio.h b/include/linux/pci-epf-virtio.h
> new file mode 100644
> index 000000000000..ae09087919a9
> --- /dev/null
> +++ b/include/linux/pci-epf-virtio.h
> @@ -0,0 +1,25 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * PCI Endpoint Function (EPF) for virtio definitions
> + */
> +#ifndef __LINUX_PCI_EPF_VIRTIO_H
> +#define __LINUX_PCI_EPF_VIRTIO_H
> +
> +#include <linux/types.h>
> +#include <linux/vringh.h>
> +#include <linux/pci-epf.h>
> +
> +struct pci_epf_vringh {
> + struct vringh vrh;
> + void __iomem *virt;
> + phys_addr_t phys;
> + size_t size;
> +};
> +
> +struct pci_epf_vringh *pci_epf_virtio_alloc_vringh(struct pci_epf *epf,
> + u64 features, u32 pfn,
> + size_t size);
> +void pci_epf_virtio_free_vringh(struct pci_epf *epf,
> + struct pci_epf_vringh *evrh);
> +
> +#endif // __LINUX_PCI_EPF_VIRTIO_H
> --
> 2.25.1
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