Re: [RFC PATCH v4 10/15] iommu/io-pgtable-arm: Implement arm_lpae_unmap_pages()

[isaacm]

On 2021-04-08 07:32, Will Deacon wrote:
On Wed, Apr 07, 2021 at 09:52:36PM -0700, Isaac J. Manjarres wrote:
Implement the unmap_pages() callback for the ARM LPAE io-pgtable
format.
Signed-off-by: Isaac J. Manjarres <isa...@codeaurora.org>
Suggested-by: Will Deacon <w...@kernel.org>
---
 drivers/iommu/io-pgtable-arm.c | 70 
++++++++++++++++++++++------------
 1 file changed, 45 insertions(+), 25 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm.c 
b/drivers/iommu/io-pgtable-arm.c
index ea66b10c04c4..6700685f81d4 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -253,8 +253,8 @@ static void __arm_lpae_set_pte(arm_lpae_iopte 
*ptep, arm_lpae_iopte pte,

 static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
                               struct iommu_iotlb_gather *gather,
-                              unsigned long iova, size_t size, int lvl,
-                              arm_lpae_iopte *ptep);
+                              unsigned long iova, size_t size, size_t pgcount,
+                              int lvl, arm_lpae_iopte *ptep);

 static void __arm_lpae_init_pte(struct arm_lpae_io_pgtable *data,
                                phys_addr_t paddr, arm_lpae_iopte prot,
@@ -298,7 +298,7 @@ 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);
-                       if (__arm_lpae_unmap(data, NULL, iova + i * sz, sz,
+                       if (__arm_lpae_unmap(data, NULL, iova + i * sz, sz, 1,
                                             lvl, tblp) != sz) {
                                WARN_ON(1);
                                return -EINVAL;
@@ -526,14 +526,14 @@ 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)
+                                      arm_lpae_iopte *ptep, size_t pgcount)
 {
        struct io_pgtable_cfg *cfg = &data->iop.cfg;
        arm_lpae_iopte pte, *tablep;
        phys_addr_t blk_paddr;
        size_t tablesz = ARM_LPAE_GRANULE(data);
        size_t split_sz = ARM_LPAE_BLOCK_SIZE(lvl, data);
-       int i, unmap_idx = -1;
+       int i, unmap_idx_start = -1, num_entries = 0, max_entries;

        if (WARN_ON(lvl == ARM_LPAE_MAX_LEVELS))
                return 0;
@@ -542,15 +542,18 @@ static size_t arm_lpae_split_blk_unmap(struct 
arm_lpae_io_pgtable *data,
        if (!tablep)
                return 0; /* Bytes unmapped */

-       if (size == split_sz)
-               unmap_idx = ARM_LPAE_LVL_IDX(iova, lvl, data);
+       if (size == split_sz) {
+               unmap_idx_start = ARM_LPAE_LVL_IDX(iova, lvl, data);
+               max_entries = (tablesz >> ilog2(sizeof(pte))) - unmap_idx_start;
+               num_entries = min_t(int, pgcount, max_entries);
+       }

        blk_paddr = iopte_to_paddr(blk_pte, data);
        pte = iopte_prot(blk_pte);

        for (i = 0; i < tablesz / sizeof(pte); i++, blk_paddr += split_sz) {

Given that we already have a 'tablesz / sizeof(pte)' expression here, 
I'd be
inclined to have either a local variable or a macro helper to get at 
the
ptes_per_table value that you also need to compute max_entries.
I think a macro might be helpful, as the number of PTEs per table is 
useful in a few places.

                /* Unmap! */
-               if (i == unmap_idx)
+               if (i >= unmap_idx_start && i < (unmap_idx_start + num_entries))
                        continue;

                __arm_lpae_init_pte(data, blk_paddr, pte, lvl, 1, &tablep[i]);
@@ -568,38 +571,45 @@ static size_t arm_lpae_split_blk_unmap(struct 
arm_lpae_io_pgtable *data,
                        return 0;

                tablep = iopte_deref(pte, data);
-       } else if (unmap_idx >= 0) {
-               io_pgtable_tlb_add_page(&data->iop, gather, iova, size);
-               return size;
+       } else if (unmap_idx_start >= 0) {
+               for (i = 0; i < num_entries; i++)
+			io_pgtable_tlb_add_page(&data->iop, gather, iova + i * size, 
size);

I suppose we could add a count paramater to the iotlb gather stuff in
future too, but for now this is fine as this series is already pretty 
big.

Okay. I can keep this in mind for the future.
Will

_______________________________________________
linux-arm-kernel mailing list
linux-arm-ker...@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu