From f9e54c3a2f5b79ecc57c7bc7d0d3521e461a2101 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Mon, 26 Aug 2024 16:43:53 -0400 Subject: vfio/pci: implement huge_fault support With the addition of pfnmap support in vmf_insert_pfn_{pmd,pud}() we can take advantage of PMD and PUD faults to PCI BAR mmaps and create more efficient mappings. PCI BARs are always a power of two and will typically get at least PMD alignment without userspace even trying. Userspace alignment for PUD mappings is also not too difficult. Consolidate faults through a single handler with a new wrapper for standard single page faults. The pre-faulting behavior of commit d71a989cf5d9 ("vfio/pci: Insert full vma on mmap'd MMIO fault") is removed in this refactoring since huge_fault will cover the bulk of the faults and results in more efficient page table usage. We also want to avoid that pre-faulted single page mappings preempt huge page mappings. Link: https://lkml.kernel.org/r/20240826204353.2228736-20-peterx@redhat.com Signed-off-by: Alex Williamson Signed-off-by: Peter Xu Cc: Alexander Gordeev Cc: Aneesh Kumar K.V Cc: Borislav Petkov Cc: Catalin Marinas Cc: Christian Borntraeger Cc: Dave Hansen Cc: David Hildenbrand Cc: Gavin Shan Cc: Gerald Schaefer Cc: Heiko Carstens Cc: Ingo Molnar Cc: Jason Gunthorpe Cc: Matthew Wilcox Cc: Niklas Schnelle Cc: Paolo Bonzini Cc: Ryan Roberts Cc: Sean Christopherson Cc: Sven Schnelle Cc: Thomas Gleixner Cc: Vasily Gorbik Cc: Will Deacon Cc: Zi Yan Signed-off-by: Andrew Morton --- drivers/vfio/pci/vfio_pci_core.c | 60 ++++++++++++++++++++++++++++------------ 1 file changed, 43 insertions(+), 17 deletions(-) (limited to 'drivers/vfio') diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c index ba0ce0075b2f..2d7478e9a62d 100644 --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -1657,14 +1658,20 @@ static unsigned long vma_to_pfn(struct vm_area_struct *vma) return (pci_resource_start(vdev->pdev, index) >> PAGE_SHIFT) + pgoff; } -static vm_fault_t vfio_pci_mmap_fault(struct vm_fault *vmf) +static vm_fault_t vfio_pci_mmap_huge_fault(struct vm_fault *vmf, + unsigned int order) { struct vm_area_struct *vma = vmf->vma; struct vfio_pci_core_device *vdev = vma->vm_private_data; unsigned long pfn, pgoff = vmf->pgoff - vma->vm_pgoff; - unsigned long addr = vma->vm_start; vm_fault_t ret = VM_FAULT_SIGBUS; + if (order && (vmf->address & ((PAGE_SIZE << order) - 1) || + vmf->address + (PAGE_SIZE << order) > vma->vm_end)) { + ret = VM_FAULT_FALLBACK; + goto out; + } + pfn = vma_to_pfn(vma); down_read(&vdev->memory_lock); @@ -1672,30 +1679,49 @@ static vm_fault_t vfio_pci_mmap_fault(struct vm_fault *vmf) if (vdev->pm_runtime_engaged || !__vfio_pci_memory_enabled(vdev)) goto out_unlock; - ret = vmf_insert_pfn(vma, vmf->address, pfn + pgoff); - if (ret & VM_FAULT_ERROR) - goto out_unlock; - - /* - * Pre-fault the remainder of the vma, abort further insertions and - * supress error if fault is encountered during pre-fault. - */ - for (; addr < vma->vm_end; addr += PAGE_SIZE, pfn++) { - if (addr == vmf->address) - continue; - - if (vmf_insert_pfn(vma, addr, pfn) & VM_FAULT_ERROR) - break; + switch (order) { + case 0: + ret = vmf_insert_pfn(vma, vmf->address, pfn + pgoff); + break; +#ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP + case PMD_ORDER: + ret = vmf_insert_pfn_pmd(vmf, __pfn_to_pfn_t(pfn + pgoff, + PFN_DEV), false); + break; +#endif +#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP + case PUD_ORDER: + ret = vmf_insert_pfn_pud(vmf, __pfn_to_pfn_t(pfn + pgoff, + PFN_DEV), false); + break; +#endif + default: + ret = VM_FAULT_FALLBACK; } out_unlock: up_read(&vdev->memory_lock); +out: + dev_dbg_ratelimited(&vdev->pdev->dev, + "%s(,order = %d) BAR %ld page offset 0x%lx: 0x%x\n", + __func__, order, + vma->vm_pgoff >> + (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT), + pgoff, (unsigned int)ret); return ret; } +static vm_fault_t vfio_pci_mmap_page_fault(struct vm_fault *vmf) +{ + return vfio_pci_mmap_huge_fault(vmf, 0); +} + static const struct vm_operations_struct vfio_pci_mmap_ops = { - .fault = vfio_pci_mmap_fault, + .fault = vfio_pci_mmap_page_fault, +#ifdef CONFIG_ARCH_SUPPORTS_HUGE_PFNMAP + .huge_fault = vfio_pci_mmap_huge_fault, +#endif }; int vfio_pci_core_mmap(struct vfio_device *core_vdev, struct vm_area_struct *vma) -- cgit v1.2.3-70-g09d2