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Thu, 12 Mar 2026 11:46:43 -0700 (PDT) Received: from localhost (2620:10d:c085:108::150d) by mail.thefacebook.com (2620:10d:c08b:78::c78f) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.2562.35; Thu, 12 Mar 2026 18:46:43 +0000 From: Matt Evans To: Alex Williamson , Leon Romanovsky , Jason Gunthorpe , Alex Mastro , Mahmoud Adam , David Matlack CC: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , Sumit Semwal , =?UTF-8?q?Christian=20K=C3=B6nig?= , Kevin Tian , Ankit Agrawal , Pranjal Shrivastava , Alistair Popple , Vivek Kasireddy , , , , , Subject: [RFC v2 PATCH 06/10] vfio/pci: Remove vfio_pci_zap_bars() Date: Thu, 12 Mar 2026 11:46:04 -0700 Message-ID: <20260312184613.3710705-7-mattev@meta.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260312184613.3710705-1-mattev@meta.com> References: <20260312184613.3710705-1-mattev@meta.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzEyMDE1MSBTYWx0ZWRfX7EzWGssMXe7X PJNMb5cf9dkFCzFFeZxryoWwC8yUo3ePXkgGEbFkhHn1dLa48DyWe2d8Lw696N6HxKjc5AlRUUa +CHbndXP005ysohRSr+908PwQ42QCkZ+z/gT9hL5iHmt+Ghxk7Bf6cgQuIprXUqetQTxtMei8Qw ms39Fu7+XYHhMXGosRCqWHJynAFrVOVthjAfBROPtetn71IHI+e3yU1fHsebgCPfaaDpCKmWE0I /EOJgGXehxLiC2apof2s2Rsd+xXKD5JGKrzGU6+OfASwaLbOYMgr6VxuA+6A8JV+OsRakb0DxWf Ha5oVwKmZduSrFGwjixBkpeklpIigwI9aFPRWIAWFtARpDCSY2UWycm0WD9MXzVeFdmte/EXP+A ZjmZiRIkNbXQmo6etVFAK9qmn5Q9KRNEA4C3XNuWME8NQ78Bf3mNHStmxBPJxQ5NLFMpL8eSboT 1jWUdII9DO9sEY50CLg== X-Proofpoint-ORIG-GUID: 2FnSa1b1xUyjhSFio7_aR8yhzALZdgDt X-Authority-Analysis: v=2.4 cv=QoJTHFyd c=1 sm=1 tr=0 ts=69b30a14 cx=c_pps a=CB4LiSf2rd0gKozIdrpkBw==:117 a=CB4LiSf2rd0gKozIdrpkBw==:17 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=7x6HtfJdh03M6CCDgxCd:22 a=855S8uPTkML1Oy45N9_h:22 a=VabnemYjAAAA:8 a=o4lYeIOqc9WSjTI1-WMA:9 a=O8hF6Hzn-FEA:10 a=gKebqoRLp9LExxC7YDUY:22 X-Proofpoint-GUID: 2FnSa1b1xUyjhSFio7_aR8yhzALZdgDt X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-12_02,2026-03-12_01,2025-10-01_01 Content-Type: text/plain; charset="utf-8" vfio_pci_zap_bars() and the wrapper vfio_pci_zap_and_down_write_memory_lock() are redundant as of "vfio/pci: Convert BAR mmap() to use a DMABUF". The DMABUFs used for BAR mappings already zap PTEs via the existing vfio_pci_dma_buf_move(), which notifies changes to the BAR space (e.g. around reset). Remove the old functions, and the various points needing to zap BARs become slightly cleaner. Signed-off-by: Matt Evans --- drivers/vfio/pci/vfio_pci_config.c | 18 ++++++------------ drivers/vfio/pci/vfio_pci_core.c | 30 +++++++----------------------- drivers/vfio/pci/vfio_pci_priv.h | 1 - 3 files changed, 13 insertions(+), 36 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci= _config.c index b4e39253f98d..c7ed28be1104 100644 --- a/drivers/vfio/pci/vfio_pci_config.c +++ b/drivers/vfio/pci/vfio_pci_config.c @@ -590,12 +590,9 @@ static int vfio_basic_config_write(struct vfio_pci_cor= e_device *vdev, int pos, virt_mem =3D !!(le16_to_cpu(*virt_cmd) & PCI_COMMAND_MEMORY); new_mem =3D !!(new_cmd & PCI_COMMAND_MEMORY); =20 - if (!new_mem) { - vfio_pci_zap_and_down_write_memory_lock(vdev); + down_write(&vdev->memory_lock); + if (!new_mem) vfio_pci_dma_buf_move(vdev, true); - } else { - down_write(&vdev->memory_lock); - } =20 /* * If the user is writing mem/io enable (new_mem/io) and we @@ -712,12 +709,9 @@ static int __init init_pci_cap_basic_perm(struct perm_= bits *perm) static void vfio_lock_and_set_power_state(struct vfio_pci_core_device *vde= v, pci_power_t state) { - if (state >=3D PCI_D3hot) { - vfio_pci_zap_and_down_write_memory_lock(vdev); + down_write(&vdev->memory_lock); + if (state >=3D PCI_D3hot) vfio_pci_dma_buf_move(vdev, true); - } else { - down_write(&vdev->memory_lock); - } =20 vfio_pci_set_power_state(vdev, state); if (__vfio_pci_memory_enabled(vdev)) @@ -908,7 +902,7 @@ static int vfio_exp_config_write(struct vfio_pci_core_d= evice *vdev, int pos, &cap); =20 if (!ret && (cap & PCI_EXP_DEVCAP_FLR)) { - vfio_pci_zap_and_down_write_memory_lock(vdev); + down_write(&vdev->memory_lock); vfio_pci_dma_buf_move(vdev, true); pci_try_reset_function(vdev->pdev); if (__vfio_pci_memory_enabled(vdev)) @@ -993,7 +987,7 @@ static int vfio_af_config_write(struct vfio_pci_core_de= vice *vdev, int pos, &cap); =20 if (!ret && (cap & PCI_AF_CAP_FLR) && (cap & PCI_AF_CAP_TP)) { - vfio_pci_zap_and_down_write_memory_lock(vdev); + down_write(&vdev->memory_lock); vfio_pci_dma_buf_move(vdev, true); pci_try_reset_function(vdev->pdev); if (__vfio_pci_memory_enabled(vdev)) diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_c= ore.c index 41224efa58d8..9e9ad97c2f7f 100644 --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c @@ -319,7 +319,7 @@ static int vfio_pci_runtime_pm_entry(struct vfio_pci_co= re_device *vdev, * The vdev power related flags are protected with 'memory_lock' * semaphore. */ - vfio_pci_zap_and_down_write_memory_lock(vdev); + down_write(&vdev->memory_lock); vfio_pci_dma_buf_move(vdev, true); =20 if (vdev->pm_runtime_engaged) { @@ -1229,7 +1229,7 @@ static int vfio_pci_ioctl_reset(struct vfio_pci_core_= device *vdev, if (!vdev->reset_works) return -EINVAL; =20 - vfio_pci_zap_and_down_write_memory_lock(vdev); + down_write(&vdev->memory_lock); =20 /* * This function can be invoked while the power state is non-D0. If @@ -1613,22 +1613,6 @@ ssize_t vfio_pci_core_write(struct vfio_device *core= _vdev, const char __user *bu } EXPORT_SYMBOL_GPL(vfio_pci_core_write); =20 -static void vfio_pci_zap_bars(struct vfio_pci_core_device *vdev) -{ - struct vfio_device *core_vdev =3D &vdev->vdev; - loff_t start =3D VFIO_PCI_INDEX_TO_OFFSET(VFIO_PCI_BAR0_REGION_INDEX); - loff_t end =3D VFIO_PCI_INDEX_TO_OFFSET(VFIO_PCI_ROM_REGION_INDEX); - loff_t len =3D end - start; - - unmap_mapping_range(core_vdev->inode->i_mapping, start, len, true); -} - -void vfio_pci_zap_and_down_write_memory_lock(struct vfio_pci_core_device *= vdev) -{ - down_write(&vdev->memory_lock); - vfio_pci_zap_bars(vdev); -} - u16 vfio_pci_memory_lock_and_enable(struct vfio_pci_core_device *vdev) { u16 cmd; @@ -2487,10 +2471,11 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_d= evice_set *dev_set, } =20 /* - * Take the memory write lock for each device and zap BAR - * mappings to prevent the user accessing the device while in - * reset. Locking multiple devices is prone to deadlock, - * runaway and unwind if we hit contention. + * Take the memory write lock for each device and + * revoke all DMABUFs, which will prevent any access + * to the device while in reset. Locking multiple + * devices is prone to deadlock, runaway and unwind if + * we hit contention. */ if (!down_write_trylock(&vdev->memory_lock)) { ret =3D -EBUSY; @@ -2498,7 +2483,6 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_dev= ice_set *dev_set, } =20 vfio_pci_dma_buf_move(vdev, true); - vfio_pci_zap_bars(vdev); } =20 if (!list_entry_is_head(vdev, diff --git a/drivers/vfio/pci/vfio_pci_priv.h b/drivers/vfio/pci/vfio_pci_p= riv.h index 37ece9b4b5bd..e201c96bbb14 100644 --- a/drivers/vfio/pci/vfio_pci_priv.h +++ b/drivers/vfio/pci/vfio_pci_priv.h @@ -78,7 +78,6 @@ void vfio_config_free(struct vfio_pci_core_device *vdev); int vfio_pci_set_power_state(struct vfio_pci_core_device *vdev, pci_power_t state); =20 -void vfio_pci_zap_and_down_write_memory_lock(struct vfio_pci_core_device *= vdev); u16 vfio_pci_memory_lock_and_enable(struct vfio_pci_core_device *vdev); void vfio_pci_memory_unlock_and_restore(struct vfio_pci_core_device *vdev, u16 cmd); --=20 2.47.3