Reduce overhead when unmapping large memory regions by batching GPA unmap
operations in 2MB-aligned chunks.

Use a dedicated constant for batch size to improve code clarity and
maintainability.

Signed-off-by: Stanislav Kinsburskii <[email protected]>
---
 drivers/hv/mshv_root.h         |    2 ++
 drivers/hv/mshv_root_hv_call.c |    2 +-
 drivers/hv/mshv_root_main.c    |   15 ++++++++++++---
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
index e3931b0f12693..97e64d5341b6e 100644
--- a/drivers/hv/mshv_root.h
+++ b/drivers/hv/mshv_root.h
@@ -32,6 +32,8 @@ static_assert(HV_HYP_PAGE_SIZE == MSHV_HV_PAGE_SIZE);
 
 #define MSHV_PIN_PAGES_BATCH_SIZE      (0x10000000ULL / HV_HYP_PAGE_SIZE)
 
+#define MSHV_MAX_UNMAP_GPA_PAGES       512
+
 struct mshv_vp {
        u32 vp_index;
        struct mshv_partition *vp_partition;
diff --git a/drivers/hv/mshv_root_hv_call.c b/drivers/hv/mshv_root_hv_call.c
index c9c274f29c3c6..0696024ccfe31 100644
--- a/drivers/hv/mshv_root_hv_call.c
+++ b/drivers/hv/mshv_root_hv_call.c
@@ -17,7 +17,7 @@
 /* Determined empirically */
 #define HV_INIT_PARTITION_DEPOSIT_PAGES 208
 #define HV_MAP_GPA_DEPOSIT_PAGES       256
-#define HV_UMAP_GPA_PAGES              512
+#define HV_UMAP_GPA_PAGES              MSHV_MAX_UNMAP_GPA_PAGES
 
 #define HV_PAGE_COUNT_2M_ALIGNED(pg_count) (!((pg_count) & (0x200 - 1)))
 
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index 7ef66c43e1515..8bf0b5af25802 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -1378,6 +1378,7 @@ mshv_map_user_memory(struct mshv_partition *partition,
 static void mshv_partition_destroy_region(struct mshv_mem_region *region)
 {
        struct mshv_partition *partition = region->partition;
+       u64 page_offset;
        u32 unmap_flags = 0;
        int ret;
 
@@ -1396,9 +1397,17 @@ static void mshv_partition_destroy_region(struct 
mshv_mem_region *region)
        if (region->flags.large_pages)
                unmap_flags |= HV_UNMAP_GPA_LARGE_PAGE;
 
-       /* ignore unmap failures and continue as process may be exiting */
-       hv_call_unmap_gpa_pages(partition->pt_id, region->start_gfn,
-                               region->nr_pages, unmap_flags);
+       for (page_offset = 0; page_offset < region->nr_pages; page_offset++) {
+               if (!region->pages[page_offset])
+                       continue;
+
+               hv_call_unmap_gpa_pages(partition->pt_id,
+                                       ALIGN(region->start_gfn + page_offset,
+                                             MSHV_MAX_UNMAP_GPA_PAGES),
+                                       MSHV_MAX_UNMAP_GPA_PAGES, unmap_flags);
+
+               page_offset += MSHV_MAX_UNMAP_GPA_PAGES - 1;
+       }
 
        mshv_region_invalidate(region);
 



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