Originally, creating the dma_ranges resource list in pre-sorted fashion was the simplest and most efficient way to enforce the order required by iova_reserve_pci_windows(). However since then at least one PCI host driver is now re-sorting the list for its own probe-time processing, which doesn't seem entirely unreasonable, so that basic assumption no longer holds. Make iommu-dma robust and get the sort order it needs by explicitly sorting, which means we can also save the effort at creation time and just build the list in whatever natural order the DT had. Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx> --- Looking at this area off the back of the XGene thread[1] made me realise that we need to do it anyway, regardless of whether it might also happen to restore the previous XGene behaviour or not. Presumably nobody's tried to use pcie-cadence-host behind an IOMMU yet... Boot-tested on Juno to make sure I hadn't got the sort comparison backwards. Robin. [1] https://lore.kernel.org/linux-pci/20220321104843.949645-1-maz@xxxxxxxxxx/ drivers/iommu/dma-iommu.c | 13 ++++++++++++- drivers/pci/of.c | 7 +------ 2 files changed, 13 insertions(+), 7 deletions(-) diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index b22034975301..91d134c0c9b1 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -20,6 +20,7 @@ #include <linux/iommu.h> #include <linux/iova.h> #include <linux/irq.h> +#include <linux/list_sort.h> #include <linux/mm.h> #include <linux/mutex.h> #include <linux/pci.h> @@ -414,6 +415,15 @@ static int cookie_init_hw_msi_region(struct iommu_dma_cookie *cookie, return 0; } +static int iommu_dma_ranges_sort(void *priv, const struct list_head *a, + const struct list_head *b) +{ + struct resource_entry *res_a = list_entry(a, typeof(*res_a), node); + struct resource_entry *res_b = list_entry(b, typeof(*res_b), node); + + return res_a->res->start > res_b->res->start; +} + static int iova_reserve_pci_windows(struct pci_dev *dev, struct iova_domain *iovad) { @@ -432,6 +442,7 @@ static int iova_reserve_pci_windows(struct pci_dev *dev, } /* Get reserved DMA windows from host bridge */ + list_sort(NULL, &bridge->dma_ranges, iommu_dma_ranges_sort); resource_list_for_each_entry(window, &bridge->dma_ranges) { end = window->res->start - window->offset; resv_iova: @@ -440,7 +451,7 @@ static int iova_reserve_pci_windows(struct pci_dev *dev, hi = iova_pfn(iovad, end); reserve_iova(iovad, lo, hi); } else if (end < start) { - /* dma_ranges list should be sorted */ + /* DMA ranges should be non-overlapping */ dev_err(&dev->dev, "Failed to reserve IOVA [%pa-%pa]\n", &start, &end); diff --git a/drivers/pci/of.c b/drivers/pci/of.c index cb2e8351c2cc..d176b4bc6193 100644 --- a/drivers/pci/of.c +++ b/drivers/pci/of.c @@ -393,12 +393,7 @@ static int devm_of_pci_get_host_bridge_resources(struct device *dev, goto failed; } - /* Keep the resource list sorted */ - resource_list_for_each_entry(entry, ib_resources) - if (entry->res->start > res->start) - break; - - pci_add_resource_offset(&entry->node, res, + pci_add_resource_offset(ib_resources, res, res->start - range.pci_addr); } -- 2.28.0.dirty
