Re: [Qemu-devel] [PATCH v7 11/13] vfio: Add function to get dirty page list

[Kirti Wankhede <kwankhede@nvidia.com>]

On 7/22/2019 2:09 PM, Yan Zhao wrote:
> On Tue, Jul 09, 2019 at 05:49:18PM +0800, Kirti Wankhede wrote:
>> Dirty page tracking (.log_sync) is part of RAM copying state, where
>> vendor driver provides the bitmap of pages which are dirtied by vendor
>> driver through migration region and as part of RAM copy, those pages
>> gets copied to file stream.
>>
>> To get dirty page bitmap:
>> - write start address, page_size and pfn count.
>> - read count of pfns copied.
>>     - Vendor driver should return 0 if driver doesn't have any page to
>>       report dirty in given range.
>>     - Vendor driver should return -1 to mark all pages dirty for given range.
>> - read data_offset, where vendor driver has written bitmap.
>> - read bitmap from the region or mmaped part of the region.
>> - Iterate above steps till page bitmap for all requested pfns are copied.
>>
>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
>> Reviewed-by: Neo Jia <cjia@nvidia.com>
>> ---
>>  hw/vfio/migration.c           | 123 ++++++++++++++++++++++++++++++++++++++++++
>>  hw/vfio/trace-events          |   1 +
>>  include/hw/vfio/vfio-common.h |   2 +
>>  3 files changed, 126 insertions(+)
>>
>> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
>> index 5fb4c5329ede..ca1a8c0f5f1f 100644
>> --- a/hw/vfio/migration.c
>> +++ b/hw/vfio/migration.c
>> @@ -269,6 +269,129 @@ static int vfio_load_device_config_state(QEMUFile *f, void *opaque)
>>      return qemu_file_get_error(f);
>>  }
>>  
>> +void vfio_get_dirty_page_list(VFIODevice *vbasedev,
>> +                              uint64_t start_pfn,
>> +                              uint64_t pfn_count,
>> +                              uint64_t page_size)
>> +{
>> +    VFIOMigration *migration = vbasedev->migration;
>> +    VFIORegion *region = &migration->region.buffer;
>> +    uint64_t count = 0;
>> +    int64_t copied_pfns = 0;
>> +    int64_t total_pfns = pfn_count;
>> +    int ret;
>> +
>> +    qemu_mutex_lock(&migration->lock);
>> +
>> +    while (total_pfns > 0) {
>> +        uint64_t bitmap_size, data_offset = 0;
>> +        uint64_t start = start_pfn + count;
>> +        void *buf = NULL;
>> +        bool buffer_mmaped = false;
>> +
>> +        ret = pwrite(vbasedev->fd, &start, sizeof(start),
>> +                 region->fd_offset + offsetof(struct vfio_device_migration_info,
>> +                                              start_pfn));
>> +        if (ret < 0) {
>> +            error_report("%s: Failed to set dirty pages start address %d %s",
>> +                         vbasedev->name, ret, strerror(errno));
>> +            goto dpl_unlock;
>> +        }
>> +
>> +        ret = pwrite(vbasedev->fd, &page_size, sizeof(page_size),
>> +                 region->fd_offset + offsetof(struct vfio_device_migration_info,
>> +                                              page_size));
>> +        if (ret < 0) {
>> +            error_report("%s: Failed to set dirty page size %d %s",
>> +                         vbasedev->name, ret, strerror(errno));
>> +            goto dpl_unlock;
>> +        }
>> +
>> +        ret = pwrite(vbasedev->fd, &total_pfns, sizeof(total_pfns),
>> +                 region->fd_offset + offsetof(struct vfio_device_migration_info,
>> +                                              total_pfns));
>> +        if (ret < 0) {
>> +            error_report("%s: Failed to set dirty page total pfns %d %s",
>> +                         vbasedev->name, ret, strerror(errno));
>> +            goto dpl_unlock;
>> +        }
>> +
>> +        /* Read copied dirty pfns */
>> +        ret = pread(vbasedev->fd, &copied_pfns, sizeof(copied_pfns),
>> +                region->fd_offset + offsetof(struct vfio_device_migration_info,
>> +                                             copied_pfns));
>> +        if (ret < 0) {
>> +            error_report("%s: Failed to get dirty pages bitmap count %d %s",
>> +                         vbasedev->name, ret, strerror(errno));
>> +            goto dpl_unlock;
>> +        }
>> +
>> +        if (copied_pfns == VFIO_DEVICE_DIRTY_PFNS_NONE) {
>> +            /*
>> +             * copied_pfns could be 0 if driver doesn't have any page to
>> +             * report dirty in given range
>> +             */
>> +            break;
>> +        } else if (copied_pfns == VFIO_DEVICE_DIRTY_PFNS_ALL) {
>> +            /* Mark all pages dirty for this range */
>> +            cpu_physical_memory_set_dirty_range(start_pfn * page_size,
>> +                                                pfn_count * page_size,
>> +                                                DIRTY_MEMORY_MIGRATION);
>> +            break;
>> +        }
>> +
>> +        bitmap_size = (BITS_TO_LONGS(copied_pfns) + 1) * sizeof(unsigned long);
> hi Kirti
> 
> why bitmap_size is 
> (BITS_TO_LONGS(copied_pfns) + 1) * sizeof(unsigned long).
> why it's not
> BITS_TO_LONGS(copied_pfns) * sizeof(unsigned long) ?
> 

It should be later. I'll update in next version.

Thanks,
Kirti


> Thanks
> Yan
> 
>> +        ret = pread(vbasedev->fd, &data_offset, sizeof(data_offset),
>> +                region->fd_offset + offsetof(struct vfio_device_migration_info,
>> +                                             data_offset));
>> +        if (ret != sizeof(data_offset)) {
>> +            error_report("%s: Failed to get migration buffer data offset %d",
>> +                         vbasedev->name, ret);
>> +            goto dpl_unlock;
>> +        }
>> +
>> +        if (region->mmaps) {
>> +            buf = find_data_region(region, data_offset, bitmap_size);
>> +        }
>> +
>> +        buffer_mmaped = (buf != NULL) ? true : false;
>> +
>> +        if (!buffer_mmaped) {
>> +            buf = g_try_malloc0(bitmap_size);
>> +            if (!buf) {
>> +                error_report("%s: Error allocating buffer ", __func__);
>> +                goto dpl_unlock;
>> +            }
>> +
>> +            ret = pread(vbasedev->fd, buf, bitmap_size,
>> +                        region->fd_offset + data_offset);
>> +            if (ret != bitmap_size) {
>> +                error_report("%s: Failed to get dirty pages bitmap %d",
>> +                             vbasedev->name, ret);
>> +                g_free(buf);
>> +                goto dpl_unlock;
>> +            }
>> +        }
>> +
>> +        cpu_physical_memory_set_dirty_lebitmap((unsigned long *)buf,
>> +                                               (start_pfn + count) * page_size,
>> +                                                copied_pfns);
>> +        count      += copied_pfns;
>> +        total_pfns -= copied_pfns;
>> +
>> +        if (!buffer_mmaped) {
>> +            g_free(buf);
>> +        }
>> +    }
>> +
>> +    trace_vfio_get_dirty_page_list(vbasedev->name, start_pfn, pfn_count,
>> +                                   page_size);
>> +
>> +dpl_unlock:
>> +    qemu_mutex_unlock(&migration->lock);
>> +}
>> +
>>  /* ---------------------------------------------------------------------- */
>>  
>>  static int vfio_save_setup(QEMUFile *f, void *opaque)
>> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
>> index ac065b559f4e..414a5e69ec5e 100644
>> --- a/hw/vfio/trace-events
>> +++ b/hw/vfio/trace-events
>> @@ -160,3 +160,4 @@ vfio_save_complete_precopy(char *name) " (%s)"
>>  vfio_load_device_config_state(char *name) " (%s)"
>>  vfio_load_state(char *name, uint64_t data) " (%s) data 0x%"PRIx64
>>  vfio_load_state_device_data(char *name, uint64_t data_offset, uint64_t data_size) " (%s) Offset 0x%"PRIx64" size 0x%"PRIx64
>> +vfio_get_dirty_page_list(char *name, uint64_t start, uint64_t pfn_count, uint64_t page_size) " (%s) start 0x%"PRIx64" pfn_count 0x%"PRIx64 " page size 0x%"PRIx64
>> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
>> index a022484d2636..dc1b83a0b4ef 100644
>> --- a/include/hw/vfio/vfio-common.h
>> +++ b/include/hw/vfio/vfio-common.h
>> @@ -222,5 +222,7 @@ int vfio_spapr_remove_window(VFIOContainer *container,
>>  
>>  int vfio_migration_probe(VFIODevice *vbasedev, Error **errp);
>>  void vfio_migration_finalize(VFIODevice *vbasedev);
>> +void vfio_get_dirty_page_list(VFIODevice *vbasedev, uint64_t start_pfn,
>> +                               uint64_t pfn_count, uint64_t page_size);
>>  
>>  #endif /* HW_VFIO_VFIO_COMMON_H */
>> -- 
>> 2.7.0
>>
>