Re: [PATCH] vfio: Support host translation granule size

[Keqian Zhu]

Hi Alex,

On 2021/3/10 7:17, Alex Williamson wrote:
> On Thu, 4 Mar 2021 21:34:46 +0800
> Kunkun Jiang <jiangkunkun@huawei.com> wrote:
> 
>> The cpu_physical_memory_set_dirty_lebitmap() can quickly deal with
>> the dirty pages of memory by bitmap-traveling, regardless of whether
>> the bitmap is aligned correctly or not.
>>
>> cpu_physical_memory_set_dirty_lebitmap() supports pages in bitmap of
>> host page size. So it'd better to set bitmap_pgsize to host page size
>> to support more translation granule sizes.
>>
>> Fixes: 87ea529c502 (vfio: Get migration capability flags for container)
>> Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
>> ---
>>  hw/vfio/common.c | 44 ++++++++++++++++++++++----------------------
>>  1 file changed, 22 insertions(+), 22 deletions(-)
>>
>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>> index 6ff1daa763..69fb5083a4 100644
>> --- a/hw/vfio/common.c
>> +++ b/hw/vfio/common.c
>> @@ -378,7 +378,7 @@ static int vfio_dma_unmap_bitmap(VFIOContainer 
>> *container,
>>  {
>>      struct vfio_iommu_type1_dma_unmap *unmap;
>>      struct vfio_bitmap *bitmap;
>> -    uint64_t pages = TARGET_PAGE_ALIGN(size) >> TARGET_PAGE_BITS;
>> +    uint64_t pages = REAL_HOST_PAGE_ALIGN(size) / qemu_real_host_page_size;
>>      int ret;
>>  
>>      unmap = g_malloc0(sizeof(*unmap) + sizeof(*bitmap));
>> @@ -390,12 +390,12 @@ static int vfio_dma_unmap_bitmap(VFIOContainer 
>> *container,
>>      bitmap = (struct vfio_bitmap *)&unmap->data;
>>  
>>      /*
>> -     * cpu_physical_memory_set_dirty_lebitmap() expects pages in bitmap of
>> -     * TARGET_PAGE_SIZE to mark those dirty. Hence set bitmap_pgsize to
>> -     * TARGET_PAGE_SIZE.
>> +     * cpu_physical_memory_set_dirty_lebitmap() supports pages in bitmap of
>> +     * qemu_real_host_page_size to mark those dirty. Hence set bitmap_pgsize
>> +     * to qemu_real_host_page_size.
> 
> 
> I don't see that this change is well supported by the code,
> cpu_physical_memory_set_dirty_lebitmap() seems to operate on
> TARGET_PAGE_SIZE, and the next three patch chunks take a detour through
> memory listener code that seem unrelated to the change described in the
> commit log.  This claims to fix something, what is actually broken?
Actually I have reported this bug long ago. 
cpu_physical_memory_set_dirty_lebitmap() expects
the granule of @bitmap to be qemu_real_host_page_size, as it uses @hpratio to 
convert the bitmap.

Thanks,
Keqian

> Thanks,
> 
> Alex
> 
>>       */
>>  
>> -    bitmap->pgsize = TARGET_PAGE_SIZE;
>> +    bitmap->pgsize = qemu_real_host_page_size;
>>      bitmap->size = ROUND_UP(pages, sizeof(__u64) * BITS_PER_BYTE) /
>>                     BITS_PER_BYTE;
>>  
>> @@ -674,16 +674,16 @@ static void vfio_listener_region_add(MemoryListener 
>> *listener,
>>          return;
>>      }
>>  
>> -    if (unlikely((section->offset_within_address_space & ~TARGET_PAGE_MASK) 
>> !=
>> -                 (section->offset_within_region & ~TARGET_PAGE_MASK))) {
>> +    if (unlikely((section->offset_within_address_space & 
>> ~qemu_real_host_page_mask) !=
>> +                 (section->offset_within_region & 
>> ~qemu_real_host_page_mask))) {
>>          error_report("%s received unaligned region", __func__);
>>          return;
>>      }
>>  
>> -    iova = TARGET_PAGE_ALIGN(section->offset_within_address_space);
>> +    iova = REAL_HOST_PAGE_ALIGN(section->offset_within_address_space);
>>      llend = int128_make64(section->offset_within_address_space);
>>      llend = int128_add(llend, section->size);
>> -    llend = int128_and(llend, int128_exts64(TARGET_PAGE_MASK));
>> +    llend = int128_and(llend, int128_exts64(qemu_real_host_page_mask));
>>  
>>      if (int128_ge(int128_make64(iova), llend)) {
>>          return;
>> @@ -892,8 +892,8 @@ static void vfio_listener_region_del(MemoryListener 
>> *listener,
>>          return;
>>      }
>>  
>> -    if (unlikely((section->offset_within_address_space & ~TARGET_PAGE_MASK) 
>> !=
>> -                 (section->offset_within_region & ~TARGET_PAGE_MASK))) {
>> +    if (unlikely((section->offset_within_address_space & 
>> ~qemu_real_host_page_mask) !=
>> +                 (section->offset_within_region & 
>> ~qemu_real_host_page_mask))) {
>>          error_report("%s received unaligned region", __func__);
>>          return;
>>      }
>> @@ -921,10 +921,10 @@ static void vfio_listener_region_del(MemoryListener 
>> *listener,
>>           */
>>      }
>>  
>> -    iova = TARGET_PAGE_ALIGN(section->offset_within_address_space);
>> +    iova = REAL_HOST_PAGE_ALIGN(section->offset_within_address_space);
>>      llend = int128_make64(section->offset_within_address_space);
>>      llend = int128_add(llend, section->size);
>> -    llend = int128_and(llend, int128_exts64(TARGET_PAGE_MASK));
>> +    llend = int128_and(llend, int128_exts64(qemu_real_host_page_mask));
>>  
>>      if (int128_ge(int128_make64(iova), llend)) {
>>          return;
>> @@ -1004,13 +1004,13 @@ static int vfio_get_dirty_bitmap(VFIOContainer 
>> *container, uint64_t iova,
>>      range->size = size;
>>  
>>      /*
>> -     * cpu_physical_memory_set_dirty_lebitmap() expects pages in bitmap of
>> -     * TARGET_PAGE_SIZE to mark those dirty. Hence set bitmap's pgsize to
>> -     * TARGET_PAGE_SIZE.
>> +     * cpu_physical_memory_set_dirty_lebitmap() supports pages in bitmap of
>> +     * qemu_real_host_page_size to mark those dirty. Hence set bitmap's 
>> pgsize
>> +     * to qemu_real_host_page_size.
>>       */
>> -    range->bitmap.pgsize = TARGET_PAGE_SIZE;
>> +    range->bitmap.pgsize = qemu_real_host_page_size;
>>  
>> -    pages = TARGET_PAGE_ALIGN(range->size) >> TARGET_PAGE_BITS;
>> +    pages = REAL_HOST_PAGE_ALIGN(range->size) / qemu_real_host_page_size;
>>      range->bitmap.size = ROUND_UP(pages, sizeof(__u64) * BITS_PER_BYTE) /
>>                                           BITS_PER_BYTE;
>>      range->bitmap.data = g_try_malloc0(range->bitmap.size);
>> @@ -1114,7 +1114,7 @@ static int vfio_sync_dirty_bitmap(VFIOContainer 
>> *container,
>>                 section->offset_within_region;
>>  
>>      return vfio_get_dirty_bitmap(container,
>> -                       
>> TARGET_PAGE_ALIGN(section->offset_within_address_space),
>> +                       
>> REAL_HOST_PAGE_ALIGN(section->offset_within_address_space),
>>                         int128_get64(section->size), ram_addr);
>>  }
>>  
>> @@ -1655,10 +1655,10 @@ static void 
>> vfio_get_iommu_info_migration(VFIOContainer *container,
>>                              header);
>>  
>>      /*
>> -     * cpu_physical_memory_set_dirty_lebitmap() expects pages in bitmap of
>> -     * TARGET_PAGE_SIZE to mark those dirty.
>> +     * cpu_physical_memory_set_dirty_lebitmap() supports pages in bitmap of
>> +     * qemu_real_host_page_size to mark those dirty.
>>       */
>> -    if (cap_mig->pgsize_bitmap & TARGET_PAGE_SIZE) {
>> +    if (cap_mig->pgsize_bitmap & qemu_real_host_page_size) {
>>          container->dirty_pages_supported = true;
>>          container->max_dirty_bitmap_size = cap_mig->max_dirty_bitmap_size;
>>          container->dirty_pgsizes = cap_mig->pgsize_bitmap;
> 
> .
>