From: Stanislav Kinsburskii <[email protected]>
>
> 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]>
Question about "packaging" of this patch. To apply cleanly, it
needs the previous two fixes applied. As such, shouldn't it be
the 3rd patch in patch set that includes the other two?
Also, there are changes in the previous two fixes that get undone
or changed by this patch (such as applying large_shift in the error
path of hv_do_map_gpa_hcall(). With a little more coordination
between the three patches, there could be less code churn and
the patches would overall be smaller.
Michael
> ---
> 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;
>
> 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;
> +
> + 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,
>
>
