On 2021-05-10 10:19, Shameerali Kolothum Thodi wrote:
Hi Robin,
-----Original Message-----
From: Robin Murphy [mailto:robin.murphy@xxxxxxx]
Sent: 07 May 2021 11:02
To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx>;
linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx;
iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: Linuxarm <linuxarm@xxxxxxxxxx>; lorenzo.pieralisi@xxxxxxx;
joro@xxxxxxxxxx; wanghuiqiang <wanghuiqiang@xxxxxxxxxx>; Guohanjun
(Hanjun Guo) <guohanjun@xxxxxxxxxx>; steven.price@xxxxxxx;
Sami.Mujawar@xxxxxxx; jon@xxxxxxxxxxxxx; eric.auger@xxxxxxxxxx
Subject: Re: [PATCH v3 08/10] iommu/arm-smmu-v3: Reserve any RMR regions
associated with a dev
On 2021-04-20 09:27, Shameer Kolothum wrote:
Get RMR regions associated with a dev reserved so that there is
a unity mapping for them in SMMU.
Signed-off-by: Shameer Kolothum
<shameerali.kolothum.thodi@xxxxxxxxxx>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 29
+++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 14e9c7034c04..8bacedf7bb34 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2531,6 +2531,34 @@ static int arm_smmu_of_xlate(struct device *dev,
struct of_phandle_args *args)
return iommu_fwspec_add_ids(dev, args->args, 1);
}
+static bool arm_smmu_dev_has_rmr(struct arm_smmu_master *master,
+ struct iommu_rmr *e)
+{
+ int i;
+
+ for (i = 0; i < master->num_sids; i++) {
+ if (e->sid == master->sids[i])
+ return true;
+ }
+
+ return false;
+}
+
+static void arm_smmu_rmr_get_resv_regions(struct device *dev,
+ struct list_head *head)
+{
+ struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+ struct arm_smmu_device *smmu = master->smmu;
+ struct iommu_rmr *rmr;
+
+ list_for_each_entry(rmr, &smmu->rmr_list, list) {
+ if (!arm_smmu_dev_has_rmr(master, rmr))
+ continue;
+
+ iommu_dma_get_rmr_resv_regions(dev, rmr, head);
+ }
+}
+
TBH I wouldn't have thought we need a driver-specific hook for this, or
is it too painful to correlate fwspec->iommu_fwnode back to the relevant
IORT node generically?
From a quick look, I think I could get rid of the above with something like below,
------8<----
+static bool iommu_dma_dev_has_rmr(struct iommu_fwspec *fwspec,
+ struct iommu_rmr *e)
+{
+ int i;
+
+ for (i = 0; i < fwspec->num_ids; i++) {
+ if (e->sid == fwspec->ids[i])
+ return true;
+ }
+
+ return false;
+}
+
+
+void iommu_dma_get_rmr_resv_regions(struct device *dev, struct list_head *list)
+{
+ struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+ struct list_head rmr_list;
+ struct iommu_rmr *rmr;
+
+ INIT_LIST_HEAD(&rmr_list);
+ if (iommu_dma_get_rmrs(fwspec->iommu_fwnode, &rmr_list))
+ return;
...
+ list_for_each_entry(rmr, &rmr_list, list) {
+
+ if (!iommu_dma_dev_has_rmr(fwspec, rmr)
+ continue;
+ ...
+ region = iommu_alloc_resv_region(rmr->base_address,
+ rmr->length, prot,
+ type);
...
+ }
+}
/**
* iommu_dma_get_resv_regions - Reserved region driver helper
* @dev: Device from iommu_get_resv_regions()
@@ -188,10 +242,11 @@ void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list)
if (!is_of_node(dev_iommu_fwspec_get(dev)->iommu_fwnode))
iort_iommu_msi_get_resv_regions(dev, list);
+ iommu_dma_get_rmr_resv_regions(dev, list);
}
----8<----
But looking at the SMMUv2 code, the fwspec->ids is MASK:SID, so I am not
sure the RMR sid can be compared directly to fwspec->ids above. Right? Or
is there a better way here?
Ah, but consider how the IDs got there in the first place ;)
A mask will never be set on ACPI systems, since IORT (intentionally)
only caters for straightforward mappings rather than arbitrary
complexity, so the assumption of fwspec ID == SID is already baked in by
virtue of arm_smmu_iort_xlate(). The IORT code is free to assume its own
behaviour!
Robin.
Thanks,
Shameer
static void arm_smmu_get_resv_regions(struct device *dev,
struct list_head *head)
{
@@ -2545,6 +2573,7 @@ static void arm_smmu_get_resv_regions(struct
device *dev,
list_add_tail(®ion->list, head);
iommu_dma_get_resv_regions(dev, head);
+ arm_smmu_rmr_get_resv_regions(dev, head);
}
static bool arm_smmu_dev_has_feature(struct device *dev,
