From: Stanislav Kinsburskii <[email protected]> Sent: Thursday,
April 30, 2026 7:52 AM
>
> Clean up hv_do_map_gpa_hcall() and hv_call_unmap_gpa_pages() after the
> preceding bug-fix patches:
>
> Move "done += completed" before the status checks so that pages mapped
> by a partially-successful batch are included in the error cleanup unmap.
> Previously these mappings were leaked on failure.
>
> While here, improve type safety and readability:
> - Change "int done" to "u64 done" to match the u64 page_count it is
> compared against, avoiding signed/unsigned comparison hazards.
> - Use u64 for loop iteration and batch size variables consistently.
> - Add proper braces to the for-loop body in hv_do_map_gpa_hcall().
> - Remove unnecessary "ret" variable from hv_call_unmap_gpa_pages().
> - Simplify the error-path unmap to use "done << large_shift" directly
> instead of mutating done in place.
>
> v3: aligned changes by 80 colons
> v2: replaced min with min_t
>
> Fixes: 621191d709b14 ("Drivers: hv: Introduce mshv_root module to expose
> /dev/mshv to
> VMMs")
> Signed-off-by: Stanislav Kinsburskii <[email protected]>
> ---
> drivers/hv/mshv_root_hv_call.c | 56
> +++++++++++++++-------------------------
> 1 file changed, 21 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/hv/mshv_root_hv_call.c b/drivers/hv/mshv_root_hv_call.c
> index e5992c324904a..e1f9e28d5a19b 100644
> --- a/drivers/hv/mshv_root_hv_call.c
> +++ b/drivers/hv/mshv_root_hv_call.c
> @@ -195,8 +195,8 @@ static int hv_do_map_gpa_hcall(u64 partition_id, u64 gfn,
> u64 page_struct_count,
> struct hv_input_map_gpa_pages *input_page;
> u64 status, *pfnlist;
> unsigned long irq_flags, large_shift = 0;
> - int ret = 0, done = 0;
> - u64 page_count = page_struct_count;
> + u64 done = 0, page_count = page_struct_count;
> + int ret = 0;
>
> if (page_count == 0 || (pages && mmio_spa))
> return -EINVAL;
> @@ -213,8 +213,8 @@ static int hv_do_map_gpa_hcall(u64 partition_id, u64 gfn,
> u64 page_struct_count,
> }
>
> while (done < page_count) {
> - ulong i, completed, remain = page_count - done;
> - int rep_count = min(remain, HV_MAP_GPA_BATCH_SIZE);
> + u64 i, completed, remain = page_count - done;
> + u64 rep_count = min_t(u64, remain, HV_MAP_GPA_BATCH_SIZE);
>
> local_irq_save(irq_flags);
> input_page = *this_cpu_ptr(hyperv_pcpu_input_arg);
> @@ -224,23 +224,14 @@ static int hv_do_map_gpa_hcall(u64 partition_id, u64
> gfn, u64 page_struct_count,
> input_page->map_flags = flags;
> pfnlist = input_page->source_gpa_page_list;
>
> - for (i = 0; i < rep_count; i++)
> - if (flags & HV_MAP_GPA_NO_ACCESS) {
> + for (i = 0; i < rep_count; i++) {
> + if (flags & HV_MAP_GPA_NO_ACCESS)
> pfnlist[i] = 0;
> - } else if (pages) {
> - u64 index = (done + i) << large_shift;
> -
> - if (index >= page_struct_count) {
> - ret = -EINVAL;
> - break;
> - }
> - pfnlist[i] = page_to_pfn(pages[index]);
> - } else {
> + else if (pages)
> + pfnlist[i] = page_to_pfn(pages[(done + i) <<
> + large_shift]);
> + else
> pfnlist[i] = mmio_spa + done + i;
> - }
> - if (ret) {
> - local_irq_restore(irq_flags);
> - break;
> }
>
> status = hv_do_rep_hypercall(HVCALL_MAP_GPA_PAGES, rep_count, 0,
> @@ -248,29 +239,26 @@ static int hv_do_map_gpa_hcall(u64 partition_id, u64
> gfn, u64 page_struct_count,
> local_irq_restore(irq_flags);
>
> completed = hv_repcomp(status);
> + done += completed;
A further cleanup: local variable "completed" is only used in these
two statements. Drop the local variable and just do:
done += hv_repcomp(status);
>
> if (hv_result_needs_memory(status)) {
> ret = hv_call_deposit_pages(NUMA_NO_NODE, partition_id,
> HV_MAP_GPA_DEPOSIT_PAGES);
> if (ret)
> break;
> -
> } else if (!hv_result_success(status)) {
> ret = hv_result_to_errno(status);
> break;
> }
> -
> - done += completed;
> }
>
> if (ret && done) {
> u32 unmap_flags = 0;
>
> - if (flags & HV_MAP_GPA_LARGE_PAGE) {
> + if (flags & HV_MAP_GPA_LARGE_PAGE)
> unmap_flags |= HV_UNMAP_GPA_LARGE_PAGE;
> - done <<= large_shift;
> - }
> - hv_call_unmap_gpa_pages(partition_id, gfn, done, unmap_flags);
> + hv_call_unmap_gpa_pages(partition_id, gfn,
> + done << large_shift, unmap_flags);
> }
>
> return ret;
> @@ -305,7 +293,7 @@ int hv_call_unmap_gpa_pages(u64 partition_id, u64 gfn,
> u64 page_count_4k,
> struct hv_input_unmap_gpa_pages *input_page;
> u64 status, page_count = page_count_4k;
> unsigned long irq_flags, large_shift = 0;
> - int ret = 0, done = 0;
> + u64 done = 0;
>
> if (page_count == 0)
> return -EINVAL;
> @@ -319,8 +307,8 @@ int hv_call_unmap_gpa_pages(u64 partition_id, u64 gfn,
> u64 page_count_4k,
> }
>
> while (done < page_count) {
> - ulong completed, remain = page_count - done;
> - int rep_count = min(remain, HV_UMAP_GPA_PAGES);
> + u64 completed, remain = page_count - done;
> + u64 rep_count = min_t(u64, remain, HV_UMAP_GPA_PAGES);
>
> local_irq_save(irq_flags);
> input_page = *this_cpu_ptr(hyperv_pcpu_input_arg);
> @@ -333,15 +321,13 @@ int hv_call_unmap_gpa_pages(u64 partition_id, u64 gfn,
> u64 page_count_4k,
> local_irq_restore(irq_flags);
>
> completed = hv_repcomp(status);
> - if (!hv_result_success(status)) {
> - ret = hv_result_to_errno(status);
> - break;
> - }
> -
> done += completed;
Same here. Drop "completed" and just do:
done += hv_repcomp(status);
> +
> + if (!hv_result_success(status))
> + return hv_result_to_errno(status);
> }
>
> - return ret;
> + return 0;
> }
>
> int hv_call_get_gpa_access_states(u64 partition_id, u32 count, u64
> gpa_base_pfn,
>
>
Michael
