[PATCH RFC 17/19] iommu/arm-smmu-v3: Add unmap_read_dirty() support

Joao Martins
2022-04-28T21:12:18Z

Mostly reuses unmap existing code with the extra addition of
marshalling into a bitmap of a page size. To tackle the race,
switch away from a plain store to a cmpxchg() and check whether
IOVA was dirtied or not once it succeeds.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 17 +++++
drivers/iommu/io-pgtable-arm.c | 78 +++++++++++++++++----
2 files changed, 82 insertions(+), 13 deletions(-)

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 5f728f8f20a2..d1fb757056cc 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2499,6 +2499,22 @@ static size_t arm_smmu_unmap_pages(struct iommu_domain *domain, unsigned long io
return ops->unmap_pages(ops, iova, pgsize, pgcount, gather);
}

+static size_t arm_smmu_unmap_pages_read_dirty(struct iommu_domain *domain,
+ unsigned long iova, size_t pgsize,
+ size_t pgcount,
+ struct iommu_iotlb_gather *gather,
+ struct iommu_dirty_bitmap *dirty)
+{
+ struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
+ struct io_pgtable_ops *ops = smmu_domain->pgtbl_ops;
+
+ if (!ops)
+ return 0;
+
+ return ops->unmap_pages_read_dirty(ops, iova, pgsize, pgcount,
+ gather, dirty);
+}
+
static void arm_smmu_flush_iotlb_all(struct iommu_domain *domain)
{
struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
@@ -2938,6 +2954,7 @@ static struct iommu_ops arm_smmu_ops = {
.free = arm_smmu_domain_free,
.read_and_clear_dirty = arm_smmu_read_and_clear_dirty,
.set_dirty_tracking_range = arm_smmu_set_dirty_tracking,
+ .unmap_pages_read_dirty = arm_smmu_unmap_pages_read_dirty,
}
};

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 361410aa836c..143ee7d73f88 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -259,10 +259,30 @@ static void __arm_lpae_clear_pte(arm_lpae_iopte *ptep, struct io_pgtable_cfg *cf
__arm_lpae_sync_pte(ptep, 1, cfg);
}

+static bool __arm_lpae_clear_dirty_pte(arm_lpae_iopte *ptep,
+ struct io_pgtable_cfg *cfg)
+{
+ arm_lpae_iopte tmp;
+ bool dirty = false;
+
+ do {
+ tmp = cmpxchg64(ptep, *ptep, 0);
+ if ((tmp & ARM_LPAE_PTE_DBM) &&
+ !(tmp & ARM_LPAE_PTE_AP_RDONLY))
+ dirty = true;
+ } while (tmp);
+
+ if (!cfg->coherent_walk)
+ __arm_lpae_sync_pte(ptep, 1, cfg);
+
+ return dirty;
+}
+
static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
struct iommu_iotlb_gather *gather,
unsigned long iova, size_t size, size_t pgcount,
- int lvl, arm_lpae_iopte *ptep);
+ int lvl, arm_lpae_iopte *ptep,
+ struct iommu_dirty_bitmap *dirty);

static void __arm_lpae_init_pte(struct arm_lpae_io_pgtable *data,
phys_addr_t paddr, arm_lpae_iopte prot,
@@ -306,8 +326,13 @@ static int arm_lpae_init_pte(struct arm_lpae_io_pgtable *data,
size_t sz = ARM_LPAE_BLOCK_SIZE(lvl, data);

tblp = ptep - ARM_LPAE_LVL_IDX(iova, lvl, data);
+
+ /*
+ * No need for dirty bitmap as arm_lpae_init_pte() is
+ * only called from __arm_lpae_map()
+ */
if (__arm_lpae_unmap(data, NULL, iova + i * sz, sz, 1,
- lvl, tblp) != sz) {
+ lvl, tblp, NULL) != sz) {
WARN_ON(1);
return -EINVAL;
}
@@ -564,7 +589,8 @@ static size_t arm_lpae_split_blk_unmap(struct arm_lpae_io_pgtable *data,
struct iommu_iotlb_gather *gather,
unsigned long iova, size_t size,
arm_lpae_iopte blk_pte, int lvl,
- arm_lpae_iopte *ptep, size_t pgcount)
+ arm_lpae_iopte *ptep, size_t pgcount,
+ struct iommu_dirty_bitmap *dirty)
{
struct io_pgtable_cfg *cfg = &data->iop.cfg;
arm_lpae_iopte pte, *tablep;
@@ -617,13 +643,15 @@ static size_t arm_lpae_split_blk_unmap(struct arm_lpae_io_pgtable *data,
return num_entries * size;
}

- return __arm_lpae_unmap(data, gather, iova, size, pgcount, lvl, tablep);
+ return __arm_lpae_unmap(data, gather, iova, size, pgcount,
+ lvl, tablep, dirty);
}

static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
struct iommu_iotlb_gather *gather,
unsigned long iova, size_t size, size_t pgcount,
- int lvl, arm_lpae_iopte *ptep)
+ int lvl, arm_lpae_iopte *ptep,
+ struct iommu_dirty_bitmap *dirty)
{
arm_lpae_iopte pte;
struct io_pgtable *iop = &data->iop;
@@ -649,7 +677,11 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
if (WARN_ON(!pte))
break;

- __arm_lpae_clear_pte(ptep, &iop->cfg);
+ if (likely(!dirty))
+ __arm_lpae_clear_pte(ptep, &iop->cfg);
+ else if (__arm_lpae_clear_dirty_pte(ptep, &iop->cfg))
+ iommu_dirty_bitmap_record(dirty, iova, size);
+

if (!iopte_leaf(pte, lvl, iop->fmt)) {
/* Also flush any partial walks */
@@ -671,17 +703,20 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
* minus the part we want to unmap
*/
return arm_lpae_split_blk_unmap(data, gather, iova, size, pte,
- lvl + 1, ptep, pgcount);
+ lvl + 1, ptep, pgcount, dirty);
}

/* Keep on walkin' */
ptep = iopte_deref(pte, data);
- return __arm_lpae_unmap(data, gather, iova, size, pgcount, lvl + 1, ptep);
+ return __arm_lpae_unmap(data, gather, iova, size, pgcount,
+ lvl + 1, ptep, dirty);
}

-static size_t arm_lpae_unmap_pages(struct io_pgtable_ops *ops, unsigned long iova,
- size_t pgsize, size_t pgcount,
- struct iommu_iotlb_gather *gather)
+static size_t __arm_lpae_unmap_pages(struct io_pgtable_ops *ops,
+ unsigned long iova,
+ size_t pgsize, size_t pgcount,
+ struct iommu_iotlb_gather *gather,
+ struct iommu_dirty_bitmap *dirty)
{
struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
struct io_pgtable_cfg *cfg = &data->iop.cfg;
@@ -697,13 +732,29 @@ static size_t arm_lpae_unmap_pages(struct io_pgtable_ops *ops, unsigned long iov
return 0;

return __arm_lpae_unmap(data, gather, iova, pgsize, pgcount,
- data->start_level, ptep);
+ data->start_level, ptep, dirty);
+}
+
+static size_t arm_lpae_unmap_pages(struct io_pgtable_ops *ops, unsigned long iova,
+ size_t pgsize, size_t pgcount,
+ struct iommu_iotlb_gather *gather)
+{
+ return __arm_lpae_unmap_pages(ops, iova, pgsize, pgcount, gather, NULL);
}

static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
size_t size, struct iommu_iotlb_gather *gather)
{
- return arm_lpae_unmap_pages(ops, iova, size, 1, gather);
+ return __arm_lpae_unmap_pages(ops, iova, size, 1, gather, NULL);
+}
+
+static size_t arm_lpae_unmap_pages_read_dirty(struct io_pgtable_ops *ops,
+ unsigned long iova,
+ size_t pgsize, size_t pgcount,
+ struct iommu_iotlb_gather *gather,
+ struct iommu_dirty_bitmap *dirty)
+{
+ return __arm_lpae_unmap_pages(ops, iova, pgsize, pgcount, gather, dirty);
}

static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops,
@@ -969,6 +1020,7 @@ arm_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg)
.iova_to_phys = arm_lpae_iova_to_phys,
.read_and_clear_dirty = arm_lpae_read_and_clear_dirty,
.set_dirty_tracking = arm_lpae_set_dirty_tracking,
+ .unmap_pages_read_dirty = arm_lpae_unmap_pages_read_dirty,
};

return data;
--
2.17.2