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Message-ID: <3c68ab13bcabe908c35388c66bf38a43f5d68c8b.1726138681.git.leon@kernel.org>
Date: Thu, 12 Sep 2024 14:15:43 +0300
From: Leon Romanovsky <leon@...nel.org>
To: Jens Axboe <axboe@...nel.dk>,
Jason Gunthorpe <jgg@...pe.ca>,
Robin Murphy <robin.murphy@....com>,
Joerg Roedel <joro@...tes.org>,
Will Deacon <will@...nel.org>,
Keith Busch <kbusch@...nel.org>,
Christoph Hellwig <hch@....de>,
"Zeng, Oak" <oak.zeng@...el.com>,
Chaitanya Kulkarni <kch@...dia.com>
Cc: Leon Romanovsky <leonro@...dia.com>,
Sagi Grimberg <sagi@...mberg.me>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Logan Gunthorpe <logang@...tatee.com>,
Yishai Hadas <yishaih@...dia.com>,
Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>,
Kevin Tian <kevin.tian@...el.com>,
Alex Williamson <alex.williamson@...hat.com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Jérôme Glisse <jglisse@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-rdma@...r.kernel.org,
iommu@...ts.linux.dev,
linux-nvme@...ts.infradead.org,
linux-pci@...r.kernel.org,
kvm@...r.kernel.org,
linux-mm@...ck.org
Subject: [RFC v2 08/21] mm/hmm: let users to tag specific PFN with DMA mapped bit
From: Leon Romanovsky <leonro@...dia.com>
Introduce new sticky flag (HMM_PFN_DMA_MAPPED), which isn't overwritten
by HMM range fault. Such flag allows users to tag specific PFNs with information
if this specific PFN was already DMA mapped.
Signed-off-by: Leon Romanovsky <leonro@...dia.com>
---
include/linux/hmm.h | 4 ++++
mm/hmm.c | 34 +++++++++++++++++++++-------------
2 files changed, 25 insertions(+), 13 deletions(-)
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 126a36571667..2999697db83a 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -23,6 +23,8 @@ struct mmu_interval_notifier;
* HMM_PFN_WRITE - if the page memory can be written to (requires HMM_PFN_VALID)
* HMM_PFN_ERROR - accessing the pfn is impossible and the device should
* fail. ie poisoned memory, special pages, no vma, etc
+ * HMM_PFN_DMA_MAPPED - Flag preserved on input-to-output transformation
+ * to mark that page is already DMA mapped
*
* On input:
* 0 - Return the current state of the page, do not fault it.
@@ -36,6 +38,8 @@ enum hmm_pfn_flags {
HMM_PFN_VALID = 1UL << (BITS_PER_LONG - 1),
HMM_PFN_WRITE = 1UL << (BITS_PER_LONG - 2),
HMM_PFN_ERROR = 1UL << (BITS_PER_LONG - 3),
+ /* Sticky lag, carried from Input to Output */
+ HMM_PFN_DMA_MAPPED = 1UL << (BITS_PER_LONG - 7),
HMM_PFN_ORDER_SHIFT = (BITS_PER_LONG - 8),
/* Input flags */
diff --git a/mm/hmm.c b/mm/hmm.c
index 7e0229ae4a5a..2a0c34d7cb2b 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -44,8 +44,10 @@ static int hmm_pfns_fill(unsigned long addr, unsigned long end,
{
unsigned long i = (addr - range->start) >> PAGE_SHIFT;
- for (; addr < end; addr += PAGE_SIZE, i++)
- range->hmm_pfns[i] = cpu_flags;
+ for (; addr < end; addr += PAGE_SIZE, i++) {
+ range->hmm_pfns[i] &= HMM_PFN_DMA_MAPPED;
+ range->hmm_pfns[i] |= cpu_flags;
+ }
return 0;
}
@@ -202,8 +204,10 @@ static int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr,
return hmm_vma_fault(addr, end, required_fault, walk);
pfn = pmd_pfn(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
- for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++)
- hmm_pfns[i] = pfn | cpu_flags;
+ for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++) {
+ hmm_pfns[i] &= HMM_PFN_DMA_MAPPED;
+ hmm_pfns[i] |= pfn | cpu_flags;
+ }
return 0;
}
#else /* CONFIG_TRANSPARENT_HUGEPAGE */
@@ -236,7 +240,7 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0);
if (required_fault)
goto fault;
- *hmm_pfn = 0;
+ *hmm_pfn = *hmm_pfn & HMM_PFN_DMA_MAPPED;
return 0;
}
@@ -253,14 +257,14 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
cpu_flags = HMM_PFN_VALID;
if (is_writable_device_private_entry(entry))
cpu_flags |= HMM_PFN_WRITE;
- *hmm_pfn = swp_offset_pfn(entry) | cpu_flags;
+ *hmm_pfn = (*hmm_pfn & HMM_PFN_DMA_MAPPED) | swp_offset_pfn(entry) | cpu_flags;
return 0;
}
required_fault =
hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0);
if (!required_fault) {
- *hmm_pfn = 0;
+ *hmm_pfn = *hmm_pfn & HMM_PFN_DMA_MAPPED;
return 0;
}
@@ -304,11 +308,11 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
pte_unmap(ptep);
return -EFAULT;
}
- *hmm_pfn = HMM_PFN_ERROR;
+ *hmm_pfn = (*hmm_pfn & HMM_PFN_DMA_MAPPED) | HMM_PFN_ERROR;
return 0;
}
- *hmm_pfn = pte_pfn(pte) | cpu_flags;
+ *hmm_pfn = (*hmm_pfn & HMM_PFN_DMA_MAPPED) | pte_pfn(pte) | cpu_flags;
return 0;
fault:
@@ -448,8 +452,10 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end,
}
pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
- for (i = 0; i < npages; ++i, ++pfn)
- hmm_pfns[i] = pfn | cpu_flags;
+ for (i = 0; i < npages; ++i, ++pfn) {
+ hmm_pfns[i] &= HMM_PFN_DMA_MAPPED;
+ hmm_pfns[i] |= pfn | cpu_flags;
+ }
goto out_unlock;
}
@@ -507,8 +513,10 @@ static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
}
pfn = pte_pfn(entry) + ((start & ~hmask) >> PAGE_SHIFT);
- for (; addr < end; addr += PAGE_SIZE, i++, pfn++)
- range->hmm_pfns[i] = pfn | cpu_flags;
+ for (; addr < end; addr += PAGE_SIZE, i++, pfn++) {
+ range->hmm_pfns[i] &= HMM_PFN_DMA_MAPPED;
+ range->hmm_pfns[i] |= pfn | cpu_flags;
+ }
spin_unlock(ptl);
return 0;
--
2.46.0
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