On 2019-11-26 10:03 a.m., James Sewart wrote:
> The PLX PEX NTB forwards DMA transactions using Requester ID's that
> don't exist as PCI devices. The devfn for a transaction is used as an
> index into a lookup table storing the origin of a transaction on the
> other side of the bridge.
>
> Add helper pci_add_dma_alias_range that can alias a range of devfns in
> dma_alias_mask.
>
> This patch aliases all possible devfn's to the NTB device so that any
> transaction coming in is governed by the mappings for the NTB.
>
> Signed-off-by: James Sewart <jamessewart@xxxxxxxxxx>
Looks good to me, save a nit below; and you may want to split this into
two patches: one that introduces the new interface and one that uses it.
Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
> ---
> drivers/pci/pci.c | 29 ++++++++++++++++++++++-------
> drivers/pci/quirks.c | 15 +++++++++++++++
> include/linux/pci.h | 1 +
> 3 files changed, 38 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index a97e2571a527..f502af1b5d10 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5854,6 +5854,18 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode,
> return 0;
> }
>
> +int _pci_add_dma_alias_range(struct pci_dev *dev, u8 devfn_from, int len)
> +{
> + if (!dev->dma_alias_mask)
> + dev->dma_alias_mask = bitmap_zalloc(U8_MAX, GFP_KERNEL);
> + if (!dev->dma_alias_mask) {
> + pci_warn(dev, "Unable to allocate DMA alias mask\n");
> + return -ENOMEM;
> + }
> + bitmap_set(dev->dma_alias_mask, devfn_from, len);
> + return 0;
> +}
> +
> /**
> * pci_add_dma_alias - Add a DMA devfn alias for a device
> * @dev: the PCI device for which alias is added
> @@ -5875,18 +5887,21 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode,
> */
> void pci_add_dma_alias(struct pci_dev *dev, u8 devfn)
> {
> - if (!dev->dma_alias_mask)
> - dev->dma_alias_mask = bitmap_zalloc(U8_MAX, GFP_KERNEL);
> - if (!dev->dma_alias_mask) {
> - pci_warn(dev, "Unable to allocate DMA alias mask\n");
> + if (_pci_add_dma_alias_range(dev, devfn, 1) != 0)
> return;
> - }
> -
> - set_bit(devfn, dev->dma_alias_mask);
> pci_info(dev, "Enabling fixed DMA alias to %02x.%d\n",
> PCI_SLOT(devfn), PCI_FUNC(devfn));
> }
>
> +void pci_add_dma_alias_range(struct pci_dev *dev, u8 devfn_from, int len)
> +{
> + int devfn_to = devfn_from + len - 1;
Nit: there should be a blank line between the variable declarations and
the code in the functions.
> + if (_pci_add_dma_alias_range(dev, devfn_from, len) != 0)
> + return;
> + pci_info(dev, "Enabling fixed DMA alias for devfn range from %02x.%d to %02x.%d\n",
> + PCI_SLOT(devfn_from), PCI_FUNC(devfn_from), PCI_SLOT(devfn_to), PCI_FUNC(devfn_to));
> +}
> +
> bool pci_devs_are_dma_aliases(struct pci_dev *dev1, struct pci_dev *dev2)
> {
> return (dev1->dma_alias_mask &&
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 320255e5e8f8..1ed230f739a4 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -5315,6 +5315,21 @@ SWITCHTEC_QUIRK(0x8574); /* PFXI 64XG3 */
> SWITCHTEC_QUIRK(0x8575); /* PFXI 80XG3 */
> SWITCHTEC_QUIRK(0x8576); /* PFXI 96XG3 */
>
> +/*
> + * PLX NTB uses devfn proxy IDs to move TLPs between NT endpoints. These IDs
> + * are used to forward responses to the originator on the other side of the
> + * NTB. Alias all possible IDs to the NTB to permit access when the IOMMU is
> + * turned on.
> + */
> +static void quirk_plx_ntb_dma_alias(struct pci_dev *pdev)
> +{
> + pci_info(pdev, "Setting PLX NTB proxy ID aliases\n");
> + /* PLX NTB may use all 256 devfns */
> + pci_add_dma_alias_range(pdev, 0, 256);
> +}
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_PLX, 0x87b0, quirk_plx_ntb_dma_alias);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_PLX, 0x87b1, quirk_plx_ntb_dma_alias);
> +
> /*
> * On Lenovo Thinkpad P50 SKUs with a Nvidia Quadro M1000M, the BIOS does
> * not always reset the secondary Nvidia GPU between reboots if the system
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 1a6cf19eac2d..6765f3d0102b 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -2324,6 +2324,7 @@ static inline struct eeh_dev *pci_dev_to_eeh_dev(struct pci_dev *pdev)
> #endif
>
> void pci_add_dma_alias(struct pci_dev *dev, u8 devfn);
> +void pci_add_dma_alias_range(struct pci_dev *dev, u8 devfn_from, int len);
> bool pci_devs_are_dma_aliases(struct pci_dev *dev1, struct pci_dev *dev2);
> int pci_for_each_dma_alias(struct pci_dev *pdev,
> int (*fn)(struct pci_dev *pdev,
>
