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a="76046049" X-IronPort-AV: E=Sophos;i="6.19,311,1754982000"; d="scan'208";a="76046049" X-CSE-ConnectionGUID: xrybInCiS3aowhHWly128g== X-CSE-MsgGUID: nzTwrWrqShaa5dXIulXDZQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,311,1754982000"; d="scan'208";a="190070965" From: Zhenzhong Duan To: qemu-devel@nongnu.org Cc: alex@shazbot.org, clg@redhat.com, eric.auger@redhat.com, mst@redhat.com, jasowang@redhat.com, peterx@redhat.com, ddutile@redhat.com, jgg@nvidia.com, nicolinc@nvidia.com, skolothumtho@nvidia.com, joao.m.martins@oracle.com, clement.mathieu--drif@eviden.com, kevin.tian@intel.com, yi.l.liu@intel.com, chao.p.peng@intel.com, Zhenzhong Duan Subject: [PATCH v8 17/23] vfio/listener: Bypass readonly region for dirty tracking Date: Mon, 17 Nov 2025 04:37:20 -0500 Message-ID: <20251117093729.1121324-18-zhenzhong.duan@intel.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20251117093729.1121324-1-zhenzhong.duan@intel.com> References: <20251117093729.1121324-1-zhenzhong.duan@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=192.198.163.9; envelope-from=zhenzhong.duan@intel.com; helo=mgamail.intel.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @intel.com) X-ZM-MESSAGEID: 1763372499405158500 Content-Type: text/plain; charset="utf-8" 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 --- hw/vfio/listener.c | 46 +++++++++++++++++++++++++++++++++----------- hw/vfio/trace-events | 1 + 2 files changed, 36 insertions(+), 11 deletions(-) diff --git a/hw/vfio/listener.c b/hw/vfio/listener.c index 3b48f6796c..ca2377d860 100644 --- a/hw/vfio/listener.c +++ b/hw/vfio/listener.c @@ -76,8 +76,13 @@ static bool vfio_log_sync_needed(const VFIOContainer *bc= ontainer) return true; } =20 -static bool vfio_listener_skipped_section(MemoryRegionSection *section) +static bool vfio_listener_skipped_section(MemoryRegionSection *section, + bool bypass_ro) { + if (bypass_ro && section->readonly) { + return true; + } + return (!memory_region_is_ram(section->mr) && !memory_region_is_iommu(section->mr)) || memory_region_is_protected(section->mr) || @@ -368,9 +373,9 @@ static bool vfio_known_safe_misalignment(MemoryRegionSe= ction *section) } =20 static bool vfio_listener_valid_section(MemoryRegionSection *section, - const char *name) + bool bypass_ro, const char *name) { - if (vfio_listener_skipped_section(section)) { + if (vfio_listener_skipped_section(section, bypass_ro)) { trace_vfio_listener_region_skip(name, section->offset_within_address_space, section->offset_within_address_space + @@ -497,7 +502,7 @@ void vfio_container_region_add(VFIOContainer *bcontaine= r, int ret; Error *err =3D NULL; =20 - if (!vfio_listener_valid_section(section, "region_add")) { + if (!vfio_listener_valid_section(section, false, "region_add")) { return; } =20 @@ -663,7 +668,7 @@ static void vfio_listener_region_del(MemoryListener *li= stener, int ret; bool try_unmap =3D true; =20 - if (!vfio_listener_valid_section(section, "region_del")) { + if (!vfio_listener_valid_section(section, false, "region_del")) { return; } =20 @@ -722,11 +727,11 @@ static void vfio_listener_region_del(MemoryListener *= listener, } =20 /* - * Fake an IOTLB entry for identity mapping which is needed by dir= ty - * tracking. In fact, in unmap_bitmap, only translated_addr field = is - * used to set dirty bitmap. + * Fake an IOTLB entry for writable identity mapping which is need= ed + * by dirty tracking. In fact, in unmap_bitmap, only translated_ad= dr + * field is used to set dirty bitmap. */ - if (!memory_region_is_iommu(section->mr)) { + if (!memory_region_is_iommu(section->mr) && !section->readonly) { entry.iova =3D iova; entry.translated_addr =3D iova; iotlb =3D &entry; @@ -834,7 +839,8 @@ static void vfio_dirty_tracking_update(MemoryListener *= listener, container_of(listener, VFIODirtyRangesListener, listener); hwaddr iova, end; =20 - if (!vfio_listener_valid_section(section, "tracking_update") || + /* Bypass readonly section as it never becomes dirty */ + if (!vfio_listener_valid_section(section, true, "tracking_update") || !vfio_get_section_iova_range(dirty->bcontainer, section, &iova, &end, NULL)) { return; @@ -1093,6 +1099,19 @@ static void vfio_iommu_map_dirty_notify(IOMMUNotifie= r *n, IOMMUTLBEntry *iotlb) if (!mr) { goto out_unlock; } + + /* + * The mapping is readonly when either it's a readonly mapping in guest + * or mapped target is readonly, bypass it for dirty tracking as it + * never becomes dirty. + */ + if (!(iotlb->perm & IOMMU_WO) || mr->readonly) { + trace_vfio_iommu_map_dirty_notify_skip_ro(iova, + iova + iotlb->addr_mask); + rcu_read_unlock(); + return; + } + translated_addr =3D memory_region_get_ram_addr(mr) + xlat; =20 ret =3D vfio_container_query_dirty_bitmap(bcontainer, iova, iotlb->add= r_mask + 1, @@ -1228,7 +1247,12 @@ static void vfio_listener_log_sync(MemoryListener *l= istener, int ret; Error *local_err =3D NULL; =20 - if (vfio_listener_skipped_section(section)) { + /* + * Bypass readonly section as it never becomes dirty, iommu memory sec= tion + * is RW and never bypassed. The readonly mappings in iommu MR are byp= assed + * in vfio_iommu_map_dirty_notify(). + */ + if (vfio_listener_skipped_section(section, true)) { return; } =20 diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events index 3c62bab764..180e3d526b 100644 --- a/hw/vfio/trace-events +++ b/hw/vfio/trace-events @@ -103,6 +103,7 @@ vfio_listener_region_del(uint64_t start, uint64_t end) = "region_del 0x%"PRIx64" - vfio_device_dirty_tracking_update(uint64_t start, uint64_t end, uint64_t m= in, uint64_t max) "section 0x%"PRIx64" - 0x%"PRIx64" -> update [0x%"PRIx64"= - 0x%"PRIx64"]" vfio_device_dirty_tracking_start(int nr_ranges, uint64_t min32, uint64_t m= ax32, uint64_t min64, uint64_t max64, uint64_t minpci, uint64_t maxpci) "nr= _ranges %d 32:[0x%"PRIx64" - 0x%"PRIx64"], 64:[0x%"PRIx64" - 0x%"PRIx64"], = pci64:[0x%"PRIx64" - 0x%"PRIx64"]" vfio_iommu_map_dirty_notify(uint64_t iova_start, uint64_t iova_end) "iommu= dirty @ 0x%"PRIx64" - 0x%"PRIx64 +vfio_iommu_map_dirty_notify_skip_ro(uint64_t iova_start, uint64_t iova_end= ) "iommu dirty @ 0x%"PRIx64" - 0x%"PRIx64 =20 # container.c vfio_container_query_dirty_bitmap(uint64_t iova, uint64_t size, uint64_t b= ackend_flag, uint64_t bitmap_size, uint64_t translated_addr, uint64_t dirty= _pages) "iova=3D0x%"PRIx64" size=3D0x%"PRIx64" backend_flag=3D0x%"PRIx64" b= itmap_size=3D0x%"PRIx64" gpa=3D0x%"PRIx64" dirty_pages=3D%"PRIu64 --=20 2.47.1