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[47.55.120.4]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4ee48e909b6sm94289501cf.32.2025.11.24.09.16.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Nov 2025 09:16:19 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vNaAl-00000001wXD-1Ugh; Mon, 24 Nov 2025 13:16:19 -0400 Date: Mon, 24 Nov 2025 13:16:19 -0400 From: Jason Gunthorpe To: ankita@nvidia.com Cc: yishaih@nvidia.com, skolothumtho@nvidia.com, kevin.tian@intel.com, alex@shazbot.org, aniketa@nvidia.com, vsethi@nvidia.com, mochs@nvidia.com, Yunxiang.Li@amd.com, yi.l.liu@intel.com, zhangdongdong@eswincomputing.com, avihaih@nvidia.com, bhelgaas@google.com, peterx@redhat.com, pstanner@redhat.com, apopple@nvidia.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, cjia@nvidia.com, kwankhede@nvidia.com, targupta@nvidia.com, zhiw@nvidia.com, danw@nvidia.com, dnigam@nvidia.com, kjaju@nvidia.com Subject: Re: [PATCH v5 1/7] vfio/nvgrace-gpu: Use faults to map device memory Message-ID: <20251124171619.GT233636@ziepe.ca> References: <20251124115926.119027-1-ankita@nvidia.com> <20251124115926.119027-2-ankita@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251124115926.119027-2-ankita@nvidia.com> On Mon, Nov 24, 2025 at 11:59:20AM +0000, ankita@nvidia.com wrote: > From: Ankit Agrawal > > To make use of the huge pfnmap support and to support zap/remap > sequence, fault/huge_fault ops based mapping mechanism needs to > be implemented. > > Currently nvgrace-gpu module relies on remap_pfn_range to do > the mapping during VM bootup. Replace it to instead rely on fault > and use vmf_insert_pfn to setup the mapping. > > Signed-off-by: Ankit Agrawal > --- > drivers/vfio/pci/nvgrace-gpu/main.c | 50 +++++++++++++++++------------ > 1 file changed, 30 insertions(+), 20 deletions(-) > > diff --git a/drivers/vfio/pci/nvgrace-gpu/main.c b/drivers/vfio/pci/nvgrace-gpu/main.c > index e346392b72f6..f74f3d8e1ebe 100644 > --- a/drivers/vfio/pci/nvgrace-gpu/main.c > +++ b/drivers/vfio/pci/nvgrace-gpu/main.c > @@ -130,6 +130,32 @@ static void nvgrace_gpu_close_device(struct vfio_device *core_vdev) > vfio_pci_core_close_device(core_vdev); > } > > +static vm_fault_t nvgrace_gpu_vfio_pci_fault(struct vm_fault *vmf) > +{ > + struct vm_area_struct *vma = vmf->vma; > + struct nvgrace_gpu_pci_core_device *nvdev = vma->vm_private_data; > + int index = vma->vm_pgoff >> (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT); This should not be a signed value. I think the right type is unsigned long. > + vm_fault_t ret = VM_FAULT_SIGBUS; > + struct mem_region *memregion; > + unsigned long pgoff, pfn; > + > + memregion = nvgrace_gpu_memregion(index, nvdev); > + if (!memregion) > + return ret; > + > + pgoff = (vmf->address - vma->vm_start) >> PAGE_SHIFT; > + pfn = PHYS_PFN(memregion->memphys) + pgoff; > + > + scoped_guard(rwsem_read, &nvdev->core_device.memory_lock) > + ret = vmf_insert_pfn(vmf->vma, vmf->address, pfn); This needs to check for this: if (vdev->pm_runtime_engaged || !__vfio_pci_memory_enabled(vdev)) goto out_unlock; So I think your series is out of order. Move patch 2 before this one, add the above lines to vfio_pci_vmf_insert_pfn() as well as a lockdep to check the memory_lock Then just call vfio_pci_vmf_insert_pfn() here and consider squashing patch 3. Jason