On 4/25/23 7:09 PM, Xuan Zhuo wrote:
On Tue, 25 Apr 2023 14:25:53 -0700, Shannon Nelson <shannon.nelson@xxxxxxx> wrote:To add a bit of flexibility with various virtio based devices, allow the caller to specify a different device id and DMA mask. This adds fields to struct virtio_pci_modern_device to specify an override device id check and a DMA mask. int (*device_id_check)(struct pci_dev *pdev); If defined by the driver, this function will be called to check that the PCI device is the vendor's expected device, and will return the found device id to be stored in mdev->id.device. This allows vendors with alternative vendor device ids to use this library on their own device BAR. u64 dma_mask; If defined by the driver, this mask will be used in a call to dma_set_mask_and_coherent() instead of the traditional DMA_BIT_MASK(64). This allows limiting the DMA space on vendor devices with address limitations. Signed-off-by: Shannon Nelson <shannon.nelson@xxxxxxx> --- drivers/virtio/virtio_pci_modern_dev.c | 37 +++++++++++++++++--------- include/linux/virtio_pci_modern.h | 6 +++++ 2 files changed, 31 insertions(+), 12 deletions(-) diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c index 869cb46bef96..1f2db76e8f91 100644 --- a/drivers/virtio/virtio_pci_modern_dev.c +++ b/drivers/virtio/virtio_pci_modern_dev.c @@ -218,21 +218,29 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev) int err, common, isr, notify, device; u32 notify_length; u32 notify_offset; + int devid; check_offsets(); - /* We only own devices >= 0x1000 and <= 0x107f: leave the rest. */ - if (pci_dev->device < 0x1000 || pci_dev->device > 0x107f) - return -ENODEV; - - if (pci_dev->device < 0x1040) { - /* Transitional devices: use the PCI subsystem device id as - * virtio device id, same as legacy driver always did. - */ - mdev->id.device = pci_dev->subsystem_device; + if (mdev->device_id_check) { + devid = mdev->device_id_check(pci_dev); + if (devid < 0) + return devid;I would want to know is there any other reason to return the errno? How about return -ENODEV directly?
Because if device_id_check() is returning an errno, it is trying to communicate some information about what went wrong, and I really get annoyed when an intermediate layer stomps on the value and makes that potentially useful information disappear.
sln
Thanks.+ mdev->id.device = devid; } else { - /* Modern devices: simply use PCI device id, but start from 0x1040. */ - mdev->id.device = pci_dev->device - 0x1040; + /* We only own devices >= 0x1000 and <= 0x107f: leave the rest. */ + if (pci_dev->device < 0x1000 || pci_dev->device > 0x107f) + return -ENODEV; + + if (pci_dev->device < 0x1040) { + /* Transitional devices: use the PCI subsystem device id as + * virtio device id, same as legacy driver always did. + */ + mdev->id.device = pci_dev->subsystem_device; + } else { + /* Modern devices: simply use PCI device id, but start from 0x1040. */ + mdev->id.device = pci_dev->device - 0x1040; + } } mdev->id.vendor = pci_dev->subsystem_vendor; @@ -260,7 +268,12 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev) return -EINVAL; } - err = dma_set_mask_and_coherent(&pci_dev->dev, DMA_BIT_MASK(64)); + if (mdev->dma_mask) + err = dma_set_mask_and_coherent(&pci_dev->dev, + mdev->dma_mask); + else + err = dma_set_mask_and_coherent(&pci_dev->dev, + DMA_BIT_MASK(64)); if (err) err = dma_set_mask_and_coherent(&pci_dev->dev, DMA_BIT_MASK(32)); diff --git a/include/linux/virtio_pci_modern.h b/include/linux/virtio_pci_modern.h index c4eeb79b0139..067ac1d789bc 100644 --- a/include/linux/virtio_pci_modern.h +++ b/include/linux/virtio_pci_modern.h @@ -38,6 +38,12 @@ struct virtio_pci_modern_device { int modern_bars; struct virtio_device_id id; + + /* optional check for vendor virtio device, returns dev_id or -ERRNO */ + int (*device_id_check)(struct pci_dev *pdev); + + /* optional mask for devices with limited DMA space */ + u64 dma_mask; }; /* -- 2.17.1
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