Hi Joao, >-----Original Message----- >From: Joao Martins <[email protected]> >Subject: Re: [PATCH 3/5] vfio/iommufd: Add >IOMMU_HWPT_GET_DIRTY_BITMAP_NO_CLEAR flag support > >On 10/09/2025 03:36, Zhenzhong Duan wrote: >> Pass IOMMU_HWPT_GET_DIRTY_BITMAP_NO_CLEAR when doing the last >dirty >> bitmap query right before unmap, no PTEs flushes. This accelerates the >> query without issue because unmap will tear down the mapping anyway. >> >> Add a new element dirty_tracking_flags in VFIOIOMMUFDContainer to >> be used for the flags of iommufd dirty tracking. Currently it is >> set to either IOMMU_HWPT_GET_DIRTY_BITMAP_NO_CLEAR or 0 based on >> the scenario. >> >> Co-developed-by: Joao Martins <[email protected]> >> Signed-off-by: Joao Martins <[email protected]> >> Signed-off-by: Zhenzhong Duan <[email protected]> >> Tested-by: Xudong Hao <[email protected]> >> Tested-by: Giovannio Cabiddu <[email protected]> >> --- >> hw/vfio/vfio-iommufd.h | 1 + >> include/system/iommufd.h | 2 +- >> backends/iommufd.c | 5 +++-- >> hw/vfio/iommufd.c | 6 +++++- >> backends/trace-events | 2 +- >> 5 files changed, 11 insertions(+), 5 deletions(-) >> >> diff --git a/hw/vfio/vfio-iommufd.h b/hw/vfio/vfio-iommufd.h >> index 07ea0f4304..e0af241c75 100644 >> --- a/hw/vfio/vfio-iommufd.h >> +++ b/hw/vfio/vfio-iommufd.h >> @@ -26,6 +26,7 @@ typedef struct VFIOIOMMUFDContainer { >> VFIOContainerBase bcontainer; >> IOMMUFDBackend *be; >> uint32_t ioas_id; >> + uint64_t dirty_tracking_flags; >> QLIST_HEAD(, VFIOIOASHwpt) hwpt_list; >> } VFIOIOMMUFDContainer; >> >> diff --git a/include/system/iommufd.h b/include/system/iommufd.h >> index c9c72ffc45..63898e7b0d 100644 >> --- a/include/system/iommufd.h >> +++ b/include/system/iommufd.h >> @@ -64,7 +64,7 @@ bool >iommufd_backend_set_dirty_tracking(IOMMUFDBackend *be, uint32_t >hwpt_id, >> bool iommufd_backend_get_dirty_bitmap(IOMMUFDBackend *be, >uint32_t hwpt_id, >> uint64_t iova, ram_addr_t >size, >> uint64_t page_size, >uint64_t *data, >> - Error **errp); >> + uint64_t flags, Error >**errp); >> bool iommufd_backend_invalidate_cache(IOMMUFDBackend *be, >uint32_t id, >> uint32_t data_type, >uint32_t entry_len, >> uint32_t *entry_num, void >*data, >> diff --git a/backends/iommufd.c b/backends/iommufd.c >> index 2a33c7ab0b..3c4f6157e2 100644 >> --- a/backends/iommufd.c >> +++ b/backends/iommufd.c >> @@ -361,7 +361,7 @@ bool >iommufd_backend_get_dirty_bitmap(IOMMUFDBackend *be, >> uint32_t hwpt_id, >> uint64_t iova, ram_addr_t >size, >> uint64_t page_size, >uint64_t *data, >> - Error **errp) >> + uint64_t flags, Error **errp) >> { >> int ret; >> struct iommu_hwpt_get_dirty_bitmap get_dirty_bitmap = { >> @@ -371,11 +371,12 @@ bool >iommufd_backend_get_dirty_bitmap(IOMMUFDBackend *be, >> .length = size, >> .page_size = page_size, >> .data = (uintptr_t)data, >> + .flags = flags, >> }; >> >> ret = ioctl(be->fd, IOMMU_HWPT_GET_DIRTY_BITMAP, >&get_dirty_bitmap); >> trace_iommufd_backend_get_dirty_bitmap(be->fd, hwpt_id, iova, >size, >> - page_size, ret ? errno : >0); >> + flags, page_size, ret ? >errno : 0); >> if (ret) { >> error_setg_errno(errp, errno, >> "IOMMU_HWPT_GET_DIRTY_BITMAP >(iova: 0x%"HWADDR_PRIx >> diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c >> index 0057488ce9..c897aa6b17 100644 >> --- a/hw/vfio/iommufd.c >> +++ b/hw/vfio/iommufd.c >> @@ -62,7 +62,7 @@ static int iommufd_cdev_unmap_one(const >VFIOContainerBase *bcontainer, >> hwaddr iova, ram_addr_t size, >> IOMMUTLBEntry *iotlb) >> { >> - const VFIOIOMMUFDContainer *container = >> + VFIOIOMMUFDContainer *container = >> container_of(bcontainer, VFIOIOMMUFDContainer, >bcontainer); >> bool need_dirty_sync = false; >> Error *local_err = NULL; >> @@ -73,9 +73,12 @@ static int iommufd_cdev_unmap_one(const >VFIOContainerBase *bcontainer, >> if (iotlb && vfio_container_dirty_tracking_is_started(bcontainer)) { >> if >(!vfio_container_devices_dirty_tracking_is_supported(bcontainer) && >> bcontainer->dirty_pages_supported) { >> + container->dirty_tracking_flags = >> + >IOMMU_HWPT_GET_DIRTY_BITMAP_NO_CLEAR; >> ret = vfio_container_query_dirty_bitmap(bcontainer, iova, >size, >> >iotlb->translated_addr, >> >&local_err); >> + container->dirty_tracking_flags = 0; > >Why not changing vfio_container_query_dirty_bitmap to pass a flags too, like >the >original patches? This is a little unnecssary odd style to pass a flag via >container structure rather and then clearing.
Just want to be simpler, original patch introduced a new parameter to almost all variants of *_query_dirty_bitmap() while the flags parameter is only used by IOMMUFD backend when doing unmap_bitmap. Currently we already have three backends, legacy VFIO, IOMMUFD and VFIO-user, only IOMMUFD need the flag. I take container->dirty_tracking_flags as a notification mechanism, so set it before vfio_container_query_dirty_bitmap() and clear it thereafter. Maybe clearing it in iommufd_query_dirty_bitmap() is easier to be acceptable? > >Part of the reason the original series had a VFIO_GET_DIRTY_NO_FLUSH for >generic >container abstraction was to not mix IOMMUFD UAPI specifics into base >container >API. Then in getting a VFIO_GET_DIRTY_NO_FLUSH, then type1 backend >could just >ignore the flag, while IOMMUFD translates it to >IOMMU_HWPT_GET_DIRTY_BITMAP_NO_CLEAR I did port original patch https://github.com/yiliu1765/qemu/commit/99f83595d79d2e4170c9e456cf1a7b9521bd4f80 But it looks complex to have 'flags' parameter everywhere. Thanks Zhenzhong
