On Mon, 2016-01-11 at 14:20 +0100, Jacek Lawrynowicz wrote: > This patch solves IOMMU support issues with PCIe non-transparent bridges > that use Requester ID look-up tables (LUT), e.g. PEX8733. Before exiting > the bridge, packet's RID is rewritten according to LUT programmed by > a driver. Modified packets are then passed to a destination bus and > processed upstream. The problem is that such packets seem to come from > non-existent nodes that are hidden behind NTB and are not discoverable > by a destination node, so IOMMU discards them. Adding DMA alias for a > given LUT entry allows IOMMU to create a proper mapping that enables > inter-node communication. > > The current DMA alias implementation supports only single alias, so it's > not possible to connect more than two nodes when IOMMU is enabled. This > implementation enables all possible aliases on a given bus (256) that > are stored in a bitset. Alias devfn is directly translated to a bit > number. The bitset is not allocated for devices that have no need for > DMA aliases. > > More details can be found in following article: > http://www.plxtech.com/files/pdf/technical/expresslane/RTC_Enabling%20MulitHostSystemDesigns.pdf > > Signed-off-by: Jacek Lawrynowicz <[email protected]>
Acked-by: David Woodhouse <[email protected]> Strictly speaking, this is more in PCI code than IOMMU code. And it doesn't actually touch the Intel VT-d code at all; the subject is a bit misleading. But I'm happy enough to add it to my intel-iommu tree if nobody else picks it up. Bjorn? > --- > drivers/iommu/iommu.c | 8 ++++---- > drivers/pci/pci.c | 19 +++++++++++++++++++ > drivers/pci/probe.c | 1 + > drivers/pci/quirks.c | 15 ++++++--------- > drivers/pci/search.c | 14 +++++++++----- > include/linux/pci.h | 15 ++++++++------- > 6 files changed, 47 insertions(+), 25 deletions(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 0e3b009..2032e1f 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -686,10 +686,10 @@ static struct iommu_group *get_pci_alias_group(struct > pci_dev *pdev, > continue; > > /* We alias them or they alias us */ > - if (((pdev->dev_flags & PCI_DEV_FLAGS_DMA_ALIAS_DEVFN) && > - pdev->dma_alias_devfn == tmp->devfn) || > - ((tmp->dev_flags & PCI_DEV_FLAGS_DMA_ALIAS_DEVFN) && > - tmp->dma_alias_devfn == pdev->devfn)) { > + if ((pdev->dma_alias_mask && > + test_bit(tmp->devfn, pdev->dma_alias_mask)) || > + ((tmp->dma_alias_mask && > + test_bit(pdev->devfn, tmp->dma_alias_mask)))) { > > group = get_pci_alias_group(tmp, devfns); > if (group) { > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 314db8c..b0d6a0a 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -4568,6 +4568,25 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode, > return 0; > } > > +/** > + * pci_add_dma_alias - Allows to add multiple devfn aliases for given device > + * @dev: the PCI device for which alias is added > + * @devfn: alias slot and function > + * > + * This helper encodes 8-bit devfn as bit number in dma_alias_mask > + */ > +void pci_add_dma_alias(struct pci_dev *dev, u8 devfn) > +{ > + if (!dev->dma_alias_mask) { > + dev->dma_alias_mask = kcalloc(BITS_TO_LONGS(U8_MAX), > + sizeof(long), GFP_KERNEL); > + dev_warn(&dev->dev, "Unable to allocate DMA alias mask.\n"); > + } > + if (dev->dma_alias_mask) > + set_bit(devfn, dev->dma_alias_mask); > +} > +EXPORT_SYMBOL_GPL(pci_add_dma_alias); > + > bool pci_device_is_present(struct pci_dev *pdev) > { > u32 v; > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > index edb1984..b23c25f 100644 > --- a/drivers/pci/probe.c > +++ b/drivers/pci/probe.c > @@ -1508,6 +1508,7 @@ static void pci_release_dev(struct device *dev) > pcibios_release_device(pci_dev); > pci_bus_put(pci_dev->bus); > kfree(pci_dev->driver_override); > + kfree(pci_dev->dma_alias_mask); > kfree(pci_dev); > } > > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c > index 7e32730..37968f7 100644 > --- a/drivers/pci/quirks.c > +++ b/drivers/pci/quirks.c > @@ -3568,8 +3568,7 @@ int pci_dev_specific_reset(struct pci_dev *dev, int > probe) > static void quirk_dma_func0_alias(struct pci_dev *dev) > { > if (PCI_FUNC(dev->devfn) != 0) { > - dev->dma_alias_devfn = PCI_DEVFN(PCI_SLOT(dev->devfn), 0); > - dev->dev_flags |= PCI_DEV_FLAGS_DMA_ALIAS_DEVFN; > + pci_add_dma_alias(dev, PCI_DEVFN(PCI_SLOT(dev->devfn), 0)); > } > } > > @@ -3584,8 +3583,7 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_RICOH, 0xe476, > quirk_dma_func0_alias); > static void quirk_dma_func1_alias(struct pci_dev *dev) > { > if (PCI_FUNC(dev->devfn) != 1) { > - dev->dma_alias_devfn = PCI_DEVFN(PCI_SLOT(dev->devfn), 1); > - dev->dev_flags |= PCI_DEV_FLAGS_DMA_ALIAS_DEVFN; > + pci_add_dma_alias(dev, PCI_DEVFN(PCI_SLOT(dev->devfn), 1)); > } > } > > @@ -3649,11 +3647,10 @@ static void quirk_fixed_dma_alias(struct pci_dev *dev) > > id = pci_match_id(fixed_dma_alias_tbl, dev); > if (id) { > - dev->dma_alias_devfn = id->driver_data; > - dev->dev_flags |= PCI_DEV_FLAGS_DMA_ALIAS_DEVFN; > - dev_info(&dev->dev, "Enabling fixed DMA alias to %02x.%d\n", > - PCI_SLOT(dev->dma_alias_devfn), > - PCI_FUNC(dev->dma_alias_devfn)); > + pci_add_dma_alias(dev, id->driver_data); > + dev_info(&dev->dev, "Enabling fixed DMA alias to %02lx.%ld\n", > + PCI_SLOT(id->driver_data), > + PCI_FUNC(id->driver_data)); > } > } > > diff --git a/drivers/pci/search.c b/drivers/pci/search.c > index a20ce7d..33e0f03 100644 > --- a/drivers/pci/search.c > +++ b/drivers/pci/search.c > @@ -40,11 +40,15 @@ int pci_for_each_dma_alias(struct pci_dev *pdev, > * If the device is broken and uses an alias requester ID for > * DMA, iterate over that too. > */ > - if (unlikely(pdev->dev_flags & PCI_DEV_FLAGS_DMA_ALIAS_DEVFN)) { > - ret = fn(pdev, PCI_DEVID(pdev->bus->number, > - pdev->dma_alias_devfn), data); > - if (ret) > - return ret; > + if (unlikely(pdev->dma_alias_mask)) { > + u8 devfn; > + > + for_each_set_bit(devfn, pdev->dma_alias_mask, U8_MAX) { > + ret = fn(pdev, PCI_DEVID(pdev->bus->number, devfn), > + data); > + if (ret) > + return ret; > + } > } > > for (bus = pdev->bus; !pci_is_root_bus(bus); bus = bus->parent) { > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 6ae25aa..ace132d 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -172,16 +172,14 @@ enum pci_dev_flags { > PCI_DEV_FLAGS_ASSIGNED = (__force pci_dev_flags_t) (1 << 2), > /* Flag for quirk use to store if quirk-specific ACS is enabled */ > PCI_DEV_FLAGS_ACS_ENABLED_QUIRK = (__force pci_dev_flags_t) (1 << 3), > - /* Flag to indicate the device uses dma_alias_devfn */ > - PCI_DEV_FLAGS_DMA_ALIAS_DEVFN = (__force pci_dev_flags_t) (1 << 4), > /* Use a PCIe-to-PCI bridge alias even if !pci_is_pcie */ > - PCI_DEV_FLAG_PCIE_BRIDGE_ALIAS = (__force pci_dev_flags_t) (1 << 5), > + PCI_DEV_FLAG_PCIE_BRIDGE_ALIAS = (__force pci_dev_flags_t) (1 << 4), > /* Do not use bus resets for device */ > - PCI_DEV_FLAGS_NO_BUS_RESET = (__force pci_dev_flags_t) (1 << 6), > + PCI_DEV_FLAGS_NO_BUS_RESET = (__force pci_dev_flags_t) (1 << 5), > /* Do not use PM reset even if device advertises NoSoftRst- */ > - PCI_DEV_FLAGS_NO_PM_RESET = (__force pci_dev_flags_t) (1 << 7), > + PCI_DEV_FLAGS_NO_PM_RESET = (__force pci_dev_flags_t) (1 << 6), > /* Get VPD from function 0 VPD */ > - PCI_DEV_FLAGS_VPD_REF_F0 = (__force pci_dev_flags_t) (1 << 8), > + PCI_DEV_FLAGS_VPD_REF_F0 = (__force pci_dev_flags_t) (1 << 7), > }; > > enum pci_irq_reroute_variant { > @@ -279,7 +277,7 @@ struct pci_dev { > u8 rom_base_reg; /* which config register controls the > ROM */ > u8 pin; /* which interrupt pin this device uses > */ > u16 pcie_flags_reg; /* cached PCIe Capabilities Register */ > - u8 dma_alias_devfn;/* devfn of DMA alias, if any */ > + unsigned long *dma_alias_mask;/* mask of enabled devfn aliases */ > > struct pci_driver *driver; /* which driver has allocated this > device */ > u64 dma_mask; /* Mask of the bits of bus address this > @@ -1238,6 +1236,9 @@ resource_size_t pcibios_iov_resource_alignment(struct > pci_dev *dev, int resno); > > int pci_set_vga_state(struct pci_dev *pdev, bool decode, > unsigned int command_bits, u32 flags); > + > +void pci_add_dma_alias(struct pci_dev *dev, u8 devfn); > + > /* kmem_cache style wrapper around pci_alloc_consistent() */ > > #include -- dwmw2
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