Messages in this thread | | | Subject | Re: [PATCH v7 3/3] iommu/tegra-smmu: Add PCI support | From | Robin Murphy <> | Date | Thu, 15 Oct 2020 10:55:52 +0100 |
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On 2020-10-15 05:13, Nicolin Chen wrote: > On Wed, Oct 14, 2020 at 06:42:36PM +0100, Robin Murphy wrote: >> On 2020-10-09 17:19, Nicolin Chen wrote: >>> This patch simply adds support for PCI devices. >>> >>> Reviewed-by: Dmitry Osipenko <digetx@gmail.com> >>> Tested-by: Dmitry Osipenko <digetx@gmail.com> >>> Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com> >>> --- >>> >>> Changelog >>> v6->v7 >>> * Renamed goto labels, suggested by Thierry. >>> v5->v6 >>> * Added Dmitry's Reviewed-by and Tested-by. >>> v4->v5 >>> * Added Dmitry's Reviewed-by >>> v3->v4 >>> * Dropped !iommu_present() check >>> * Added CONFIG_PCI check in the exit path >>> v2->v3 >>> * Replaced ternary conditional operator with if-else in .device_group() >>> * Dropped change in tegra_smmu_remove() >>> v1->v2 >>> * Added error-out labels in tegra_smmu_probe() >>> * Dropped pci_request_acs() since IOMMU core would call it. >>> >>> drivers/iommu/tegra-smmu.c | 35 +++++++++++++++++++++++++---------- >>> 1 file changed, 25 insertions(+), 10 deletions(-) >>> >>> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c >>> index be29f5977145..2941d6459076 100644 >>> --- a/drivers/iommu/tegra-smmu.c >>> +++ b/drivers/iommu/tegra-smmu.c >>> @@ -10,6 +10,7 @@ >>> #include <linux/kernel.h> >>> #include <linux/of.h> >>> #include <linux/of_device.h> >>> +#include <linux/pci.h> >>> #include <linux/platform_device.h> >>> #include <linux/slab.h> >>> #include <linux/spinlock.h> >>> @@ -865,7 +866,11 @@ static struct iommu_group *tegra_smmu_device_group(struct device *dev) >>> group->smmu = smmu; >>> group->soc = soc; >>> - group->group = iommu_group_alloc(); >>> + if (dev_is_pci(dev)) >>> + group->group = pci_device_group(dev); >> >> Just to check, is it OK to have two or more swgroups "owning" the same >> iommu_group if an existing one gets returned here? It looks like that might >> not play nice with the use of iommu_group_set_iommudata(). > > Do you mean by "gets returned here" the "IS_ERR" check below?
I mean that unlike iommu_group_alloc()/generic_device_group(), pci_device_group() may give you back a group that already contains another device and has already been set up from that device's perspective. This can happen for topological reasons like requester ID aliasing through a PCI-PCIe bridge or lack of isolation between functions.
Robin.
>>> + else >>> + group->group = generic_device_group(dev); >>> + >>> if (IS_ERR(group->group)) { >>> devm_kfree(smmu->dev, group); >>> mutex_unlock(&smmu->lock);
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