>-----Original Message-----
>From: Eric Auger <[email protected]>
>Subject: Re: [PATCH v7 20/23] vfio: Bypass readonly region for dirty tracking
>
>
>
>On 10/24/25 10:43 AM, Zhenzhong Duan wrote:
>> When doing ditry tracking or calculating dirty tracking range, readonly
>dirty tracking or when ...
>> regions can be bypassed, because corresponding DMA mappings are
>readonly
>> and never become dirty.
>>
>> This can optimize dirty tracking a bit for passthrough device.
>>
>> Signed-off-by: Zhenzhong Duan <[email protected]>
>> ---
>> hw/vfio/listener.c | 11 +++++++++--
>> 1 file changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/vfio/listener.c b/hw/vfio/listener.c
>> index 0862b2b834..cbd86c79af 100644
>> --- a/hw/vfio/listener.c
>> +++ b/hw/vfio/listener.c
>> @@ -828,7 +828,8 @@ static void
>vfio_dirty_tracking_update(MemoryListener *listener,
>> container_of(listener, VFIODirtyRangesListener, listener);
>> hwaddr iova, end;
>>
>> - if (!vfio_listener_valid_section(section, false, "tracking_update") ||
>> + /* Bypass readonly section as it never become dirty */
>> + if (!vfio_listener_valid_section(section, true, "tracking_update") ||
>> !vfio_get_section_iova_range(dirty->bcontainer, section,
>> &iova, &end, NULL)) {
>> return;
>> @@ -1087,6 +1088,12 @@ static void
>vfio_iommu_map_dirty_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)
>> if (!mr) {
>> goto out_unlock;
>> }
>> +
>> + if (!(iotlb->perm & IOMMU_WO) || mr->readonly) {
>> + rcu_read_unlock();
>> + return;
>This change is less obvsious compared to the others. Might be worth
>explaining why you add it.
OK
>> + }
>> +
>> translated_addr = memory_region_get_ram_addr(mr) + xlat;
>>
>> ret = vfio_container_query_dirty_bitmap(bcontainer, iova,
>iotlb->addr_mask + 1,
>> @@ -1222,7 +1229,7 @@ static void
>vfio_listener_log_sync(MemoryListener *listener,
>> int ret;
>> Error *local_err = NULL;
>>
>> - if (vfio_listener_skipped_section(section, false)) {
>> + if (vfio_listener_skipped_section(section, true)) {
>the false -> true change might be squashed into the 18/23 patch while
>explainig why you set this value.
OK, will refactor this patch and patch18
Thanks
Zhenzhong
