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Message-ID: <ee3dd0c5-5e44-634d-7ab7-7a4c9c1cd4f7@amd.com>
Date: Wed, 15 Mar 2023 20:25:19 -0700
From: Shannon Nelson <shannon.nelson@....com>
To: Jason Wang <jasowang@...hat.com>
Cc: mst@...hat.com, virtualization@...ts.linux-foundation.org,
brett.creeley@....com, davem@...emloft.net, netdev@...r.kernel.org,
kuba@...nel.org, drivers@...sando.io
Subject: Re: [PATCH RFC v2 virtio 3/7] pds_vdpa: virtio bar setup for vdpa
On 3/15/23 12:05 AM, Jason Wang wrote:
> On Thu, Mar 9, 2023 at 9:31 AM Shannon Nelson <shannon.nelson@....com> wrote:
>>
>> The PDS vDPA device has a virtio BAR for describing itself, and
>> the pds_vdpa driver needs to access it. Here we copy liberally
>> from the existing drivers/virtio/virtio_pci_modern_dev.c as it
>> has what we need, but we need to modify it so that it can work
>> with our device id and so we can use our own DMA mask.
>
> By passing a pointer to a customized id probing routine to vp_modern_probe()?
The only real differences are that we needed to cut out the device id
checks to use our vDPA VF device id, and remove
dma_set_mask_and_coherent() because we need a different DMA_BIT_MASK().
Maybe a function pointer to something that can validate the device id,
and a bitmask for setting DMA mapping; if they are 0/NULL, use the
default device id check and DMA mask.
Adding them as extra arguments to the function call seems a bit messy,
maybe add them to the struct virtio_pci_modern_device and the caller can
set them as overrides if needed?
struct virtio_pci_modern_device {
...
int (*device_id_check_override(struct pci_dev *pdev));
u64 dma_mask_override;
}
sln
>
> Thanks
>
>
>>
>> We suspect there is room for discussion here about making the
>> existing code a little more flexible, but we thought we'd at
>> least start the discussion here.
>>
>> Signed-off-by: Shannon Nelson <shannon.nelson@....com>
>> ---
>> drivers/vdpa/pds/Makefile | 1 +
>> drivers/vdpa/pds/aux_drv.c | 14 ++
>> drivers/vdpa/pds/aux_drv.h | 1 +
>> drivers/vdpa/pds/debugfs.c | 1 +
>> drivers/vdpa/pds/vdpa_dev.c | 1 +
>> drivers/vdpa/pds/virtio_pci.c | 281 ++++++++++++++++++++++++++++++++++
>> drivers/vdpa/pds/virtio_pci.h | 8 +
>> 7 files changed, 307 insertions(+)
>> create mode 100644 drivers/vdpa/pds/virtio_pci.c
>> create mode 100644 drivers/vdpa/pds/virtio_pci.h
>>
>> diff --git a/drivers/vdpa/pds/Makefile b/drivers/vdpa/pds/Makefile
>> index 13b50394ec64..ca2efa8c6eb5 100644
>> --- a/drivers/vdpa/pds/Makefile
>> +++ b/drivers/vdpa/pds/Makefile
>> @@ -4,6 +4,7 @@
>> obj-$(CONFIG_PDS_VDPA) := pds_vdpa.o
>>
>> pds_vdpa-y := aux_drv.o \
>> + virtio_pci.o \
>> vdpa_dev.o
>>
>> pds_vdpa-$(CONFIG_DEBUG_FS) += debugfs.o
>> diff --git a/drivers/vdpa/pds/aux_drv.c b/drivers/vdpa/pds/aux_drv.c
>> index 63e40ae68211..28158d0d98a5 100644
>> --- a/drivers/vdpa/pds/aux_drv.c
>> +++ b/drivers/vdpa/pds/aux_drv.c
>> @@ -4,6 +4,7 @@
>> #include <linux/auxiliary_bus.h>
>> #include <linux/pci.h>
>> #include <linux/vdpa.h>
>> +#include <linux/virtio_pci_modern.h>
>>
>> #include <linux/pds/pds_core.h>
>> #include <linux/pds/pds_auxbus.h>
>> @@ -12,6 +13,7 @@
>> #include "aux_drv.h"
>> #include "debugfs.h"
>> #include "vdpa_dev.h"
>> +#include "virtio_pci.h"
>>
>> static const struct auxiliary_device_id pds_vdpa_id_table[] = {
>> { .name = PDS_VDPA_DEV_NAME, },
>> @@ -49,8 +51,19 @@ static int pds_vdpa_probe(struct auxiliary_device *aux_dev,
>> if (err)
>> goto err_aux_unreg;
>>
>> + /* Find the virtio configuration */
>> + vdpa_aux->vd_mdev.pci_dev = padev->vf->pdev;
>> + err = pds_vdpa_probe_virtio(&vdpa_aux->vd_mdev);
>> + if (err) {
>> + dev_err(dev, "Unable to probe for virtio configuration: %pe\n",
>> + ERR_PTR(err));
>> + goto err_free_mgmt_info;
>> + }
>> +
>> return 0;
>>
>> +err_free_mgmt_info:
>> + pci_free_irq_vectors(padev->vf->pdev);
>> err_aux_unreg:
>> padev->ops->unregister_client(padev);
>> err_free_mem:
>> @@ -65,6 +78,7 @@ static void pds_vdpa_remove(struct auxiliary_device *aux_dev)
>> struct pds_vdpa_aux *vdpa_aux = auxiliary_get_drvdata(aux_dev);
>> struct device *dev = &aux_dev->dev;
>>
>> + pds_vdpa_remove_virtio(&vdpa_aux->vd_mdev);
>> pci_free_irq_vectors(vdpa_aux->padev->vf->pdev);
>>
>> vdpa_aux->padev->ops->unregister_client(vdpa_aux->padev);
>> diff --git a/drivers/vdpa/pds/aux_drv.h b/drivers/vdpa/pds/aux_drv.h
>> index 94ba7abcaa43..87ac3c01c476 100644
>> --- a/drivers/vdpa/pds/aux_drv.h
>> +++ b/drivers/vdpa/pds/aux_drv.h
>> @@ -16,6 +16,7 @@ struct pds_vdpa_aux {
>>
>> int vf_id;
>> struct dentry *dentry;
>> + struct virtio_pci_modern_device vd_mdev;
>>
>> int nintrs;
>> };
>> diff --git a/drivers/vdpa/pds/debugfs.c b/drivers/vdpa/pds/debugfs.c
>> index 7b7e90fd6578..aa5e9677fe74 100644
>> --- a/drivers/vdpa/pds/debugfs.c
>> +++ b/drivers/vdpa/pds/debugfs.c
>> @@ -1,6 +1,7 @@
>> // SPDX-License-Identifier: GPL-2.0-only
>> /* Copyright(c) 2023 Advanced Micro Devices, Inc */
>>
>> +#include <linux/virtio_pci_modern.h>
>> #include <linux/vdpa.h>
>>
>> #include <linux/pds/pds_core.h>
>> diff --git a/drivers/vdpa/pds/vdpa_dev.c b/drivers/vdpa/pds/vdpa_dev.c
>> index bd840688503c..15d623297203 100644
>> --- a/drivers/vdpa/pds/vdpa_dev.c
>> +++ b/drivers/vdpa/pds/vdpa_dev.c
>> @@ -4,6 +4,7 @@
>> #include <linux/pci.h>
>> #include <linux/vdpa.h>
>> #include <uapi/linux/vdpa.h>
>> +#include <linux/virtio_pci_modern.h>
>>
>> #include <linux/pds/pds_core.h>
>> #include <linux/pds/pds_adminq.h>
>> diff --git a/drivers/vdpa/pds/virtio_pci.c b/drivers/vdpa/pds/virtio_pci.c
>> new file mode 100644
>> index 000000000000..cb879619dac3
>> --- /dev/null
>> +++ b/drivers/vdpa/pds/virtio_pci.c
>> @@ -0,0 +1,281 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +
>> +/*
>> + * adapted from drivers/virtio/virtio_pci_modern_dev.c, v6.0-rc1
>> + */
>> +
>> +#include <linux/virtio_pci_modern.h>
>> +#include <linux/pci.h>
>> +
>> +#include "virtio_pci.h"
>> +
>> +/*
>> + * pds_vdpa_map_capability - map a part of virtio pci capability
>> + * @mdev: the modern virtio-pci device
>> + * @off: offset of the capability
>> + * @minlen: minimal length of the capability
>> + * @align: align requirement
>> + * @start: start from the capability
>> + * @size: map size
>> + * @len: the length that is actually mapped
>> + * @pa: physical address of the capability
>> + *
>> + * Returns the io address of for the part of the capability
>> + */
>> +static void __iomem *
>> +pds_vdpa_map_capability(struct virtio_pci_modern_device *mdev, int off,
>> + size_t minlen, u32 align, u32 start, u32 size,
>> + size_t *len, resource_size_t *pa)
>> +{
>> + struct pci_dev *dev = mdev->pci_dev;
>> + u8 bar;
>> + u32 offset, length;
>> + void __iomem *p;
>> +
>> + pci_read_config_byte(dev, off + offsetof(struct virtio_pci_cap,
>> + bar),
>> + &bar);
>> + pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, offset),
>> + &offset);
>> + pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
>> + &length);
>> +
>> + /* Check if the BAR may have changed since we requested the region. */
>> + if (bar >= PCI_STD_NUM_BARS || !(mdev->modern_bars & (1 << bar))) {
>> + dev_err(&dev->dev,
>> + "virtio_pci: bar unexpectedly changed to %u\n", bar);
>> + return NULL;
>> + }
>> +
>> + if (length <= start) {
>> + dev_err(&dev->dev,
>> + "virtio_pci: bad capability len %u (>%u expected)\n",
>> + length, start);
>> + return NULL;
>> + }
>> +
>> + if (length - start < minlen) {
>> + dev_err(&dev->dev,
>> + "virtio_pci: bad capability len %u (>=%zu expected)\n",
>> + length, minlen);
>> + return NULL;
>> + }
>> +
>> + length -= start;
>> +
>> + if (start + offset < offset) {
>> + dev_err(&dev->dev,
>> + "virtio_pci: map wrap-around %u+%u\n",
>> + start, offset);
>> + return NULL;
>> + }
>> +
>> + offset += start;
>> +
>> + if (offset & (align - 1)) {
>> + dev_err(&dev->dev,
>> + "virtio_pci: offset %u not aligned to %u\n",
>> + offset, align);
>> + return NULL;
>> + }
>> +
>> + if (length > size)
>> + length = size;
>> +
>> + if (len)
>> + *len = length;
>> +
>> + if (minlen + offset < minlen ||
>> + minlen + offset > pci_resource_len(dev, bar)) {
>> + dev_err(&dev->dev,
>> + "virtio_pci: map virtio %zu@%u out of range on bar %i length %lu\n",
>> + minlen, offset,
>> + bar, (unsigned long)pci_resource_len(dev, bar));
>> + return NULL;
>> + }
>> +
>> + p = pci_iomap_range(dev, bar, offset, length);
>> + if (!p)
>> + dev_err(&dev->dev,
>> + "virtio_pci: unable to map virtio %u@%u on bar %i\n",
>> + length, offset, bar);
>> + else if (pa)
>> + *pa = pci_resource_start(dev, bar) + offset;
>> +
>> + return p;
>> +}
>> +
>> +/**
>> + * virtio_pci_find_capability - walk capabilities to find device info.
>> + * @dev: the pci device
>> + * @cfg_type: the VIRTIO_PCI_CAP_* value we seek
>> + * @ioresource_types: IORESOURCE_MEM and/or IORESOURCE_IO.
>> + * @bars: the bitmask of BARs
>> + *
>> + * Returns offset of the capability, or 0.
>> + */
>> +static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
>> + u32 ioresource_types, int *bars)
>> +{
>> + int pos;
>> +
>> + for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR);
>> + pos > 0;
>> + pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
>> + u8 type, bar;
>> +
>> + pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
>> + cfg_type),
>> + &type);
>> + pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
>> + bar),
>> + &bar);
>> +
>> + /* Ignore structures with reserved BAR values */
>> + if (bar >= PCI_STD_NUM_BARS)
>> + continue;
>> +
>> + if (type == cfg_type) {
>> + if (pci_resource_len(dev, bar) &&
>> + pci_resource_flags(dev, bar) & ioresource_types) {
>> + *bars |= (1 << bar);
>> + return pos;
>> + }
>> + }
>> + }
>> + return 0;
>> +}
>> +
>> +/*
>> + * pds_vdpa_probe_virtio: probe the modern virtio pci device, note that the
>> + * caller is required to enable PCI device before calling this function.
>> + * @mdev: the modern virtio-pci device
>> + *
>> + * Return 0 on succeed otherwise fail
>> + */
>> +int pds_vdpa_probe_virtio(struct virtio_pci_modern_device *mdev)
>> +{
>> + struct pci_dev *pci_dev = mdev->pci_dev;
>> + int err, common, isr, notify, device;
>> + u32 notify_length;
>> + u32 notify_offset;
>> +
>> + /* check for a common config: if not, use legacy mode (bar 0). */
>> + common = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_COMMON_CFG,
>> + IORESOURCE_IO | IORESOURCE_MEM,
>> + &mdev->modern_bars);
>> + if (!common) {
>> + dev_info(&pci_dev->dev,
>> + "virtio_pci: missing common config\n");
>> + return -ENODEV;
>> + }
>> +
>> + /* If common is there, these should be too... */
>> + isr = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_ISR_CFG,
>> + IORESOURCE_IO | IORESOURCE_MEM,
>> + &mdev->modern_bars);
>> + notify = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_NOTIFY_CFG,
>> + IORESOURCE_IO | IORESOURCE_MEM,
>> + &mdev->modern_bars);
>> + if (!isr || !notify) {
>> + dev_err(&pci_dev->dev,
>> + "virtio_pci: missing capabilities %i/%i/%i\n",
>> + common, isr, notify);
>> + return -EINVAL;
>> + }
>> +
>> + /* Device capability is only mandatory for devices that have
>> + * device-specific configuration.
>> + */
>> + device = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_DEVICE_CFG,
>> + IORESOURCE_IO | IORESOURCE_MEM,
>> + &mdev->modern_bars);
>> +
>> + err = pci_request_selected_regions(pci_dev, mdev->modern_bars,
>> + "virtio-pci-modern");
>> + if (err)
>> + return err;
>> +
>> + err = -EINVAL;
>> + mdev->common = pds_vdpa_map_capability(mdev, common,
>> + sizeof(struct virtio_pci_common_cfg),
>> + 4, 0,
>> + sizeof(struct virtio_pci_common_cfg),
>> + NULL, NULL);
>> + if (!mdev->common)
>> + goto err_map_common;
>> + mdev->isr = pds_vdpa_map_capability(mdev, isr, sizeof(u8), 1,
>> + 0, 1, NULL, NULL);
>> + if (!mdev->isr)
>> + goto err_map_isr;
>> +
>> + /* Read notify_off_multiplier from config space. */
>> + pci_read_config_dword(pci_dev,
>> + notify + offsetof(struct virtio_pci_notify_cap,
>> + notify_off_multiplier),
>> + &mdev->notify_offset_multiplier);
>> + /* Read notify length and offset from config space. */
>> + pci_read_config_dword(pci_dev,
>> + notify + offsetof(struct virtio_pci_notify_cap,
>> + cap.length),
>> + ¬ify_length);
>> +
>> + pci_read_config_dword(pci_dev,
>> + notify + offsetof(struct virtio_pci_notify_cap,
>> + cap.offset),
>> + ¬ify_offset);
>> +
>> + /* We don't know how many VQs we'll map, ahead of the time.
>> + * If notify length is small, map it all now.
>> + * Otherwise, map each VQ individually later.
>> + */
>> + if ((u64)notify_length + (notify_offset % PAGE_SIZE) <= PAGE_SIZE) {
>> + mdev->notify_base = pds_vdpa_map_capability(mdev, notify,
>> + 2, 2,
>> + 0, notify_length,
>> + &mdev->notify_len,
>> + &mdev->notify_pa);
>> + if (!mdev->notify_base)
>> + goto err_map_notify;
>> + } else {
>> + mdev->notify_map_cap = notify;
>> + }
>> +
>> + /* Again, we don't know how much we should map, but PAGE_SIZE
>> + * is more than enough for all existing devices.
>> + */
>> + if (device) {
>> + mdev->device = pds_vdpa_map_capability(mdev, device, 0, 4,
>> + 0, PAGE_SIZE,
>> + &mdev->device_len,
>> + NULL);
>> + if (!mdev->device)
>> + goto err_map_device;
>> + }
>> +
>> + return 0;
>> +
>> +err_map_device:
>> + if (mdev->notify_base)
>> + pci_iounmap(pci_dev, mdev->notify_base);
>> +err_map_notify:
>> + pci_iounmap(pci_dev, mdev->isr);
>> +err_map_isr:
>> + pci_iounmap(pci_dev, mdev->common);
>> +err_map_common:
>> + pci_release_selected_regions(pci_dev, mdev->modern_bars);
>> + return err;
>> +}
>> +
>> +void pds_vdpa_remove_virtio(struct virtio_pci_modern_device *mdev)
>> +{
>> + struct pci_dev *pci_dev = mdev->pci_dev;
>> +
>> + if (mdev->device)
>> + pci_iounmap(pci_dev, mdev->device);
>> + if (mdev->notify_base)
>> + pci_iounmap(pci_dev, mdev->notify_base);
>> + pci_iounmap(pci_dev, mdev->isr);
>> + pci_iounmap(pci_dev, mdev->common);
>> + pci_release_selected_regions(pci_dev, mdev->modern_bars);
>> +}
>> diff --git a/drivers/vdpa/pds/virtio_pci.h b/drivers/vdpa/pds/virtio_pci.h
>> new file mode 100644
>> index 000000000000..f017cfa1173c
>> --- /dev/null
>> +++ b/drivers/vdpa/pds/virtio_pci.h
>> @@ -0,0 +1,8 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/* Copyright(c) 2023 Advanced Micro Devices, Inc */
>> +
>> +#ifndef _PDS_VIRTIO_PCI_H_
>> +#define _PDS_VIRTIO_PCI_H_
>> +int pds_vdpa_probe_virtio(struct virtio_pci_modern_device *mdev);
>> +void pds_vdpa_remove_virtio(struct virtio_pci_modern_device *mdev);
>> +#endif /* _PDS_VIRTIO_PCI_H_ */
>> --
>> 2.17.1
>>
>
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