Hi,
On 2020/2/25 2:23, Jean-Philippe Brucker wrote:
From: Jean-Philippe Brucker <[email protected]>
The SMMU provides a Stall model for handling page faults in platform
devices. It is similar to PCI PRI, but doesn't require devices to have
their own translation cache. Instead, faulting transactions are parked and
the OS is given a chance to fix the page tables and retry the transaction.
Enable stall for devices that support it (opt-in by firmware). When an
event corresponds to a translation error, call the IOMMU fault handler. If
the fault is recoverable, it will call us back to terminate or continue
the stall.
Signed-off-by: Jean-Philippe Brucker <[email protected]>
---
drivers/iommu/arm-smmu-v3.c | 271 ++++++++++++++++++++++++++++++++++--
drivers/iommu/of_iommu.c | 5 +-
include/linux/iommu.h | 2 +
3 files changed, 269 insertions(+), 9 deletions(-)
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 6a5987cce03f..da5dda5ba26a 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -374,6 +374,13 @@
#define CMDQ_PRI_1_GRPID GENMASK_ULL(8, 0)
#define CMDQ_PRI_1_RESP GENMASK_ULL(13, 12)
[...]
+static int arm_smmu_page_response(struct device *dev,
+ struct iommu_fault_event *unused,
+ struct iommu_page_response *resp)
+{
+ struct arm_smmu_cmdq_ent cmd = {0};
+ struct arm_smmu_master *master = dev_iommu_fwspec_get(dev)->iommu_priv;
Here can use 'dev_to_master' ?
Cheers,
Zaibo
.
+ int sid = master->streams[0].id;
+
+ if (master->stall_enabled) {
+ cmd.opcode = CMDQ_OP_RESUME;
+ cmd.resume.sid = sid;
+ cmd.resume.stag = resp->grpid;
+ switch (resp->code) {
+ case IOMMU_PAGE_RESP_INVALID:
+ case IOMMU_PAGE_RESP_FAILURE:
+ cmd.resume.resp = CMDQ_RESUME_0_RESP_ABORT;
+ break;
+ case IOMMU_PAGE_RESP_SUCCESS:
+ cmd.resume.resp = CMDQ_RESUME_0_RESP_RETRY;
+ break;
+ default:
+ return -EINVAL;
+ }
+ } else {
+ /* TODO: insert PRI response here */
+ return -ENODEV;
+ }
+
+ arm_smmu_cmdq_issue_cmd(master->smmu, &cmd);
+ /*
+ * Don't send a SYNC, it doesn't do anything for RESUME or PRI_RESP.
+ * RESUME consumption guarantees that the stalled transaction will be
+ * terminated... at some point in the future. PRI_RESP is fire and
+ * forget.
+ */
+
+ return 0;
+}
+
[...]
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