From: Jason Gunthorpe <jgg@ziepe.ca>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
peterx@redhat.com, mitchell.augustin@canonical.com,
clg@redhat.com, akpm@linux-foundation.org, linux-mm@kvack.org
Subject: Re: [PATCH 5/5] vfio/type1: Use mapping page mask for pfnmaps
Date: Fri, 14 Feb 2025 15:27:04 -0400 [thread overview]
Message-ID: <20250214192704.GD3696814@ziepe.ca> (raw)
In-Reply-To: <20250205231728.2527186-6-alex.williamson@redhat.com>
On Wed, Feb 05, 2025 at 04:17:21PM -0700, Alex Williamson wrote:
> @@ -590,15 +592,23 @@ static int vaddr_get_pfns(struct mm_struct *mm, unsigned long vaddr,
> vma = vma_lookup(mm, vaddr);
>
> if (vma && vma->vm_flags & VM_PFNMAP) {
> - ret = follow_fault_pfn(vma, mm, vaddr, pfn, prot & IOMMU_WRITE);
> + unsigned long pgmask;
> +
> + ret = follow_fault_pfn(vma, mm, vaddr, pfn, &pgmask,
> + prot & IOMMU_WRITE);
> if (ret == -EAGAIN)
> goto retry;
>
> if (!ret) {
> - if (is_invalid_reserved_pfn(*pfn))
> - ret = 1;
> - else
> + if (is_invalid_reserved_pfn(*pfn)) {
> + unsigned long epfn;
> +
> + epfn = (((*pfn << PAGE_SHIFT) + ~pgmask + 1)
> + & pgmask) >> PAGE_SHIFT;
That seems a bit indirect
epfn = ((*pfn) | (~pgmask >> PAGE_SHIFT)) + 1;
?
> + ret = min_t(int, npages, epfn - *pfn);
It is nitty but the int's here should be long, and npages should be
unsigned long..
Jason
next prev parent reply other threads:[~2025-02-14 19:27 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-05 23:17 [PATCH 0/5] vfio: Improve DMA mapping performance for huge pfnmaps Alex Williamson
2025-02-05 23:17 ` [PATCH 4/5] mm: Provide page mask in struct follow_pfnmap_args Alex Williamson
2025-02-07 1:38 ` Mitchell Augustin
2025-02-14 17:17 ` Alex Williamson
2025-02-14 21:39 ` David Hildenbrand
2025-02-17 21:56 ` Alex Williamson
2025-02-14 19:14 ` Jason Gunthorpe
2025-02-05 23:17 ` [PATCH 5/5] vfio/type1: Use mapping page mask for pfnmaps Alex Williamson
2025-02-07 1:39 ` Mitchell Augustin
2025-02-14 19:27 ` Jason Gunthorpe [this message]
2025-02-17 21:52 ` Alex Williamson
2025-02-14 19:46 ` Matthew Wilcox
2025-02-17 19:33 ` Alex Williamson
2025-02-06 19:14 ` [PATCH 0/5] vfio: Improve DMA mapping performance for huge pfnmaps Peter Xu
2025-02-07 1:39 ` Mitchell Augustin
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