Re: [PATCH v3 04/13] vfio/common: Add VFIOBitmap and alloc function

[Joao Martins]

On 06/03/2023 13:20, Cédric Le Goater wrote:
> On 3/4/23 02:43, Joao Martins wrote:
>> From: Avihai Horon <avihaih@nvidia.com>
>>
>> There are already two places where dirty page bitmap allocation and
>> calculations are done in open code. With device dirty page tracking
>> being added in next patches, there are going to be even more places.
>>
>> To avoid code duplication, introduce VFIOBitmap struct and corresponding
>> alloc function and use them where applicable.
>>
>> Signed-off-by: Avihai Horon <avihaih@nvidia.com>
>> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> 
> One minor comment, only in case you respin,
> 
> Reviewed-by: Cédric Le Goater <clg@redhat.com>
> 

Thanks!

>>   hw/vfio/common.c | 75 +++++++++++++++++++++++++++++-------------------
>>   1 file changed, 46 insertions(+), 29 deletions(-)
>>
>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>> index 4c801513136a..151e7f40b73d 100644
>> --- a/hw/vfio/common.c
>> +++ b/hw/vfio/common.c
>> @@ -320,6 +320,27 @@ const MemoryRegionOps vfio_region_ops = {
>>    * Device state interfaces
>>    */
>>   +typedef struct {
>> +    unsigned long *bitmap;
>> +    hwaddr size;
>> +    hwaddr pages;
>> +} VFIOBitmap;
>> +
>> +static int vfio_bitmap_alloc(VFIOBitmap *vbmap, hwaddr size)
>> +{
>> +    vbmap->pages = REAL_HOST_PAGE_ALIGN(size) / qemu_real_host_page_size();
>> +    vbmap->size = ROUND_UP(vbmap->pages, sizeof(__u64) * BITS_PER_BYTE) /
>> +                                         BITS_PER_BYTE;
>> +    vbmap->bitmap = g_try_malloc0(vbmap->size);
>> +    if (!vbmap->bitmap) {
>> +        errno = ENOMEM;
>> +
>> +        return -errno;
> 
> vfio_bitmap_alloc() could simply return ENOMEM now.
> 
Gotcha.

>> +    }
>> +
>> +    return 0;
>> +}
>> +
>>   bool vfio_mig_active(void)
>>   {
>>       VFIOGroup *group;
>> @@ -468,9 +489,14 @@ static int vfio_dma_unmap_bitmap(VFIOContainer 
>> *container,
>>   {
>>       struct vfio_iommu_type1_dma_unmap *unmap;
>>       struct vfio_bitmap *bitmap;
>> -    uint64_t pages = REAL_HOST_PAGE_ALIGN(size) / 
>> qemu_real_host_page_size();
>> +    VFIOBitmap vbmap;
>>       int ret;
>>   +    ret = vfio_bitmap_alloc(&vbmap, size);
>> +    if (ret) {
>> +        return -errno;
>> +    }
>> +
>>       unmap = g_malloc0(sizeof(*unmap) + sizeof(*bitmap));
>>         unmap->argsz = sizeof(*unmap) + sizeof(*bitmap);
>> @@ -484,35 +510,28 @@ static int vfio_dma_unmap_bitmap(VFIOContainer 
>> *container,
>>        * qemu_real_host_page_size to mark those dirty. Hence set 
>> bitmap_pgsize
>>        * to qemu_real_host_page_size.
>>        */
>> -
>>       bitmap->pgsize = qemu_real_host_page_size();
>> -    bitmap->size = ROUND_UP(pages, sizeof(__u64) * BITS_PER_BYTE) /
>> -                   BITS_PER_BYTE;
>> +    bitmap->size = vbmap.size;
>> +    bitmap->data = (__u64 *)vbmap.bitmap;
>>   -    if (bitmap->size > container->max_dirty_bitmap_size) {
>> -        error_report("UNMAP: Size of bitmap too big 0x%"PRIx64,
>> -                     (uint64_t)bitmap->size);
>> +    if (vbmap.size > container->max_dirty_bitmap_size) {
>> +        error_report("UNMAP: Size of bitmap too big 0x%"PRIx64, vbmap.size);
>>           ret = -E2BIG;
>>           goto unmap_exit;
>>       }
>>   -    bitmap->data = g_try_malloc0(bitmap->size);
>> -    if (!bitmap->data) {
>> -        ret = -ENOMEM;
>> -        goto unmap_exit;
>> -    }
>> -
>>       ret = ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, unmap);
>>       if (!ret) {
>> -        cpu_physical_memory_set_dirty_lebitmap((unsigned long 
>> *)bitmap->data,
>> -                iotlb->translated_addr, pages);
>> +        cpu_physical_memory_set_dirty_lebitmap(vbmap.bitmap,
>> +                iotlb->translated_addr, vbmap.pages);
>>       } else {
>>           error_report("VFIO_UNMAP_DMA with DIRTY_BITMAP : %m");
>>       }
>>   -    g_free(bitmap->data);
>>   unmap_exit:
>>       g_free(unmap);
>> +    g_free(vbmap.bitmap);
>> +
>>       return ret;
>>   }
>>   @@ -1329,7 +1348,7 @@ static int vfio_get_dirty_bitmap(VFIOContainer
>> *container, uint64_t iova,
>>   {
>>       struct vfio_iommu_type1_dirty_bitmap *dbitmap;
>>       struct vfio_iommu_type1_dirty_bitmap_get *range;
>> -    uint64_t pages;
>> +    VFIOBitmap vbmap;
>>       int ret;
>>         if (!container->dirty_pages_supported) {
>> @@ -1339,6 +1358,11 @@ static int vfio_get_dirty_bitmap(VFIOContainer
>> *container, uint64_t iova,
>>           return 0;
>>       }
>>   +    ret = vfio_bitmap_alloc(&vbmap, size);
>> +    if (ret) {
>> +        return -errno;
>> +    }
>> +
>>       dbitmap = g_malloc0(sizeof(*dbitmap) + sizeof(*range));
>>         dbitmap->argsz = sizeof(*dbitmap) + sizeof(*range);
>> @@ -1353,15 +1377,8 @@ static int vfio_get_dirty_bitmap(VFIOContainer
>> *container, uint64_t iova,
>>        * to qemu_real_host_page_size.
>>        */
>>       range->bitmap.pgsize = qemu_real_host_page_size();
>> -
>> -    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);
>> -    if (!range->bitmap.data) {
>> -        ret = -ENOMEM;
>> -        goto err_out;
>> -    }
>> +    range->bitmap.size = vbmap.size;
>> +    range->bitmap.data = (__u64 *)vbmap.bitmap;
>>         ret = ioctl(container->fd, VFIO_IOMMU_DIRTY_PAGES, dbitmap);
>>       if (ret) {
>> @@ -1372,14 +1389,14 @@ static int vfio_get_dirty_bitmap(VFIOContainer
>> *container, uint64_t iova,
>>           goto err_out;
>>       }
>>   -    cpu_physical_memory_set_dirty_lebitmap((unsigned long
>> *)range->bitmap.data,
>> -                                            ram_addr, pages);
>> +    cpu_physical_memory_set_dirty_lebitmap(vbmap.bitmap, ram_addr,
>> +                                           vbmap.pages);
>>         trace_vfio_get_dirty_bitmap(container->fd, range->iova, range->size,
>>                                   range->bitmap.size, ram_addr);
>>   err_out:
>> -    g_free(range->bitmap.data);
>>       g_free(dbitmap);
>> +    g_free(vbmap.bitmap);
>>         return ret;
>>   }
>