Messages in this thread | | | Date | Fri, 10 Jun 2022 14:46:52 +0800 | Subject | Re: [PATCH v8 02/11] iommu: Add max_pasids field in struct dev_iommu | From | Baolu Lu <> |
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On 2022/6/10 03:01, Raj, Ashok wrote: > On Tue, Jun 07, 2022 at 09:49:33AM +0800, Lu Baolu wrote: >> Use this field to save the number of PASIDs that a device is able to >> consume. It is a generic attribute of a device and lifting it into the >> per-device dev_iommu struct could help to avoid the boilerplate code >> in various IOMMU drivers. >> >> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> >> --- >> include/linux/iommu.h | 2 ++ >> drivers/iommu/iommu.c | 26 ++++++++++++++++++++++++++ >> 2 files changed, 28 insertions(+) >> >> diff --git a/include/linux/iommu.h b/include/linux/iommu.h >> index 03fbb1b71536..d50afb2c9a09 100644 >> --- a/include/linux/iommu.h >> +++ b/include/linux/iommu.h >> @@ -364,6 +364,7 @@ struct iommu_fault_param { >> * @fwspec: IOMMU fwspec data >> * @iommu_dev: IOMMU device this device is linked to >> * @priv: IOMMU Driver private data >> + * @max_pasids: number of PASIDs device can consume >> * >> * TODO: migrate other per device data pointers under iommu_dev_data, e.g. >> * struct iommu_group *iommu_group; >> @@ -375,6 +376,7 @@ struct dev_iommu { >> struct iommu_fwspec *fwspec; >> struct iommu_device *iommu_dev; >> void *priv; >> + u32 max_pasids; >> }; >> >> int iommu_device_register(struct iommu_device *iommu, >> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >> index 847ad47a2dfd..adac85ccde73 100644 >> --- a/drivers/iommu/iommu.c >> +++ b/drivers/iommu/iommu.c >> @@ -20,6 +20,7 @@ >> #include <linux/idr.h> >> #include <linux/err.h> >> #include <linux/pci.h> >> +#include <linux/pci-ats.h> > > Is this needed for this patch?
Yes. It's for pci_max_pasids().
> >> #include <linux/bitops.h> >> #include <linux/property.h> >> #include <linux/fsl/mc.h> >> @@ -218,6 +219,30 @@ static void dev_iommu_free(struct device *dev) >> kfree(param); >> } >> >> +static u32 dev_iommu_get_max_pasids(struct device *dev) >> +{ >> + u32 max_pasids = dev->iommu->iommu_dev->max_pasids; >> + u32 num_bits; >> + int ret; >> + >> + if (!max_pasids) >> + return 0; >> + >> + if (dev_is_pci(dev)) { >> + ret = pci_max_pasids(to_pci_dev(dev)); >> + if (ret < 0) >> + return 0; >> + >> + return min_t(u32, max_pasids, ret); > > Ah.. that answers my other question to consider device pasid-max. I guess > if we need any enforcement of restricting devices that aren't supporting > the full PASID, that will be done by some higher layer?
The mm->pasid style of SVA is explicitly enabled through iommu_dev_enable_feature(IOMMU_DEV_FEAT_SVA). The IOMMU driver specific restriction might be put there?
> > too many returns in this function, maybe setup all returns to the end of > the function might be elegant?
I didn't find cleanup room after a quick scan of the code. But sure, let me go through code again offline.
> >> + } >> + >> + ret = device_property_read_u32(dev, "pasid-num-bits", &num_bits); >> + if (ret) >> + return 0; >> + >> + return min_t(u32, max_pasids, 1UL << num_bits); >> +} >> + >> static int __iommu_probe_device(struct device *dev, struct list_head *group_list) >> { >> const struct iommu_ops *ops = dev->bus->iommu_ops; >> @@ -243,6 +268,7 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list >> } >> >> dev->iommu->iommu_dev = iommu_dev; >> + dev->iommu->max_pasids = dev_iommu_get_max_pasids(dev); >> >> group = iommu_group_get_for_dev(dev); >> if (IS_ERR(group)) { >> -- >> 2.25.1 >>
Best regards, Baolu
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