[PATCH v4 11/12] iommu: Per-domain I/O page fault handling

Lu Baolu
2022-04-21T05:25:10Z

Tweak the I/O page fault handling framework to route the page faults to
the domain and call the page fault handler retrieved from the domain.
This makes the I/O page fault handling framework possible to serve more
usage scenarios as long as they have an IOMMU domain and install a page
fault handler in it. Some unused functions are also removed to avoid
dead code.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/iommu/iommu-sva-lib.h | 1 -
drivers/iommu/io-pgfault.c | 69 ++++++-----------------------------
drivers/iommu/iommu-sva-lib.c | 20 ----------
3 files changed, 12 insertions(+), 78 deletions(-)

diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h
index 0f33472e5212..90d4bd3a61b1 100644
--- a/drivers/iommu/iommu-sva-lib.h
+++ b/drivers/iommu/iommu-sva-lib.h
@@ -8,7 +8,6 @@
#include <linux/ioasid.h>
#include <linux/mm_types.h>

-struct mm_struct *iommu_sva_find(ioasid_t pasid);
struct mm_struct *iommu_sva_domain_mm(struct iommu_domain *domain);

/* I/O Page fault */
diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c
index 1df8c1dcae77..fc1b2bdeedf8 100644
--- a/drivers/iommu/io-pgfault.c
+++ b/drivers/iommu/io-pgfault.c
@@ -69,62 +69,6 @@ static int iopf_complete_group(struct device *dev, struct iopf_fault *iopf,
return iommu_page_response(dev, &resp);
}

-static enum iommu_page_response_code
-iopf_handle_single(struct iopf_fault *iopf)
-{
- vm_fault_t ret;
- struct mm_struct *mm;
- struct vm_area_struct *vma;
- unsigned int access_flags = 0;
- unsigned int fault_flags = FAULT_FLAG_REMOTE;
- struct iommu_fault_page_request *prm = &iopf->fault.prm;
- enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID;
-
- if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID))
- return status;
-
- mm = iommu_sva_find(prm->pasid);
- if (IS_ERR_OR_NULL(mm))
- return status;
-
- mmap_read_lock(mm);
-
- vma = find_extend_vma(mm, prm->addr);
- if (!vma)
- /* Unmapped area */
- goto out_put_mm;
-
- if (prm->perm & IOMMU_FAULT_PERM_READ)
- access_flags |= VM_READ;
-
- if (prm->perm & IOMMU_FAULT_PERM_WRITE) {
- access_flags |= VM_WRITE;
- fault_flags |= FAULT_FLAG_WRITE;
- }
-
- if (prm->perm & IOMMU_FAULT_PERM_EXEC) {
- access_flags |= VM_EXEC;
- fault_flags |= FAULT_FLAG_INSTRUCTION;
- }
-
- if (!(prm->perm & IOMMU_FAULT_PERM_PRIV))
- fault_flags |= FAULT_FLAG_USER;
-
- if (access_flags & ~vma->vm_flags)
- /* Access fault */
- goto out_put_mm;
-
- ret = handle_mm_fault(vma, prm->addr, fault_flags, NULL);
- status = ret & VM_FAULT_ERROR ? IOMMU_PAGE_RESP_INVALID :
- IOMMU_PAGE_RESP_SUCCESS;
-
-out_put_mm:
- mmap_read_unlock(mm);
- mmput(mm);
-
- return status;
-}
-
static void iopf_handle_group(struct work_struct *work)
{
struct iopf_group *group;
@@ -134,12 +78,23 @@ static void iopf_handle_group(struct work_struct *work)
group = container_of(work, struct iopf_group, work);

list_for_each_entry_safe(iopf, next, &group->faults, list) {
+ struct iommu_domain *domain;
+
+ domain = iommu_get_domain_for_dev_pasid_async(group->dev,
+ iopf->fault.prm.pasid);
+ if (!domain || !domain->iopf_handler)
+ status = IOMMU_PAGE_RESP_INVALID;
+
/*
* For the moment, errors are sticky: don't handle subsequent
* faults in the group if there is an error.
*/
if (status == IOMMU_PAGE_RESP_SUCCESS)
- status = iopf_handle_single(iopf);
+ status = domain->iopf_handler(&iopf->fault,
+ domain->fault_data);
+
+ if (domain)
+ iommu_domain_put_async(domain);

if (!(iopf->fault.prm.flags &
IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE))
diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
index 1024c61519dc..d84cffaeb331 100644
--- a/drivers/iommu/iommu-sva-lib.c
+++ b/drivers/iommu/iommu-sva-lib.c
@@ -69,26 +69,6 @@ static int iommu_sva_alloc_pasid(struct mm_struct *mm,
return ret;
}

-/* ioasid_find getter() requires a void * argument */
-static bool __mmget_not_zero(void *mm)
-{
- return mmget_not_zero(mm);
-}
-
-/**
- * iommu_sva_find() - Find mm associated to the given PASID
- * @pasid: Process Address Space ID assigned to the mm
- *
- * On success a reference to the mm is taken, and must be released with mmput().
- *
- * Returns the mm corresponding to this PASID, or an error if not found.
- */
-struct mm_struct *iommu_sva_find(ioasid_t pasid)
-{
- return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero);
-}
-EXPORT_SYMBOL_GPL(iommu_sva_find);
-
/*
* Get or put an ioas for a shared memory.
*/
--
2.25.1