When doing ditry tracking or calculating dirty tracking range, readonly
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 <zhenzhong.duan@intel.com>
---
 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;
+    }
+
     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)) {
         return;
     }
 
-- 
2.47.1

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 <zhenzhong.duan@intel.com>
> ---
>  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.
> +    }
> +
>      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.

Eric
>          return;
>      }
>

On 10/24/25 10:43, Zhenzhong Duan wrote:
> When doing ditry tracking or calculating dirty tracking range, readonly
> 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 <zhenzhong.duan@intel.com>
> ---
>   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) {


In case you resend, please add a trace event.

Anyhow,

Reviewed-by: Cédric Le Goater <clg@redhat.com>

Thanks,

C.


> +        rcu_read_unlock();
> +        return;
> +    }
> +
>       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)) {
>           return;
>       }
>   

>-----Original Message-----
>From: Cédric Le Goater <clg@redhat.com>
>Subject: Re: [PATCH v7 20/23] vfio: Bypass readonly region for dirty tracking
>
>On 10/24/25 10:43, Zhenzhong Duan wrote:
>> When doing ditry tracking or calculating dirty tracking range, readonly
>> 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 <zhenzhong.duan@intel.com>
>> ---
>>   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) {
>
>
>In case you resend, please add a trace event.

OK, will add:

  trace_vfio_iommu_map_dirty_notify_skip_ro(iova, iova + iotlb->addr_mask);

Thanks
Zhenzhong

>
>Anyhow,
>
>Reviewed-by: Cédric Le Goater <clg@redhat.com>
>
>Thanks,
>
>C.
>
>
>> +        rcu_read_unlock();
>> +        return;
>> +    }
>> +
>>       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)) {
>>           return;
>>       }
>>