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From: Alex Williamson <alex.williamson@redhat.com>
To: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, cohuck@redhat.com, jgg@ziepe.ca
Subject: [PATCH v2 1/3] vfio/type1: Support faulting PFNMAP vmas
Date: Tue, 05 May 2020 15:54:44 -0600
Message-ID: <158871568480.15589.17339878308143043906.stgit@gimli.home> (raw)
In-Reply-To: <158871401328.15589.17598154478222071285.stgit@gimli.home>

With conversion to follow_pfn(), DMA mapping a PFNMAP range depends on
the range being faulted into the vma.  Add support to manually provide
that, in the same way as done on KVM with hva_to_pfn_remapped().

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
 drivers/vfio/vfio_iommu_type1.c |   36 +++++++++++++++++++++++++++++++++---
 1 file changed, 33 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index cc1d64765ce7..4a4cb7cd86b2 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -317,6 +317,32 @@ static int put_pfn(unsigned long pfn, int prot)
 	return 0;
 }
 
+static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm,
+			    unsigned long vaddr, unsigned long *pfn,
+			    bool write_fault)
+{
+	int ret;
+
+	ret = follow_pfn(vma, vaddr, pfn);
+	if (ret) {
+		bool unlocked = false;
+
+		ret = fixup_user_fault(NULL, mm, vaddr,
+				       FAULT_FLAG_REMOTE |
+				       (write_fault ?  FAULT_FLAG_WRITE : 0),
+				       &unlocked);
+		if (unlocked)
+			return -EAGAIN;
+
+		if (ret)
+			return ret;
+
+		ret = follow_pfn(vma, vaddr, pfn);
+	}
+
+	return ret;
+}
+
 static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
 			 int prot, unsigned long *pfn)
 {
@@ -339,12 +365,16 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
 
 	vaddr = untagged_addr(vaddr);
 
+retry:
 	vma = find_vma_intersection(mm, vaddr, vaddr + 1);
 
 	if (vma && vma->vm_flags & VM_PFNMAP) {
-		if (!follow_pfn(vma, vaddr, pfn) &&
-		    is_invalid_reserved_pfn(*pfn))
-			ret = 0;
+		ret = follow_fault_pfn(vma, mm, vaddr, pfn, prot & IOMMU_WRITE);
+		if (ret == -EAGAIN)
+			goto retry;
+
+		if (!ret && !is_invalid_reserved_pfn(*pfn))
+			ret = -EFAULT;
 	}
 done:
 	up_read(&mm->mmap_sem);


  reply index

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-05 21:54 [PATCH v2 0/3] vfio-pci: Block user access to disabled device MMIO Alex Williamson
2020-05-05 21:54 ` Alex Williamson [this message]
2020-05-07 21:24   ` [PATCH v2 1/3] vfio/type1: Support faulting PFNMAP vmas Peter Xu
2020-05-07 21:47     ` Alex Williamson
2020-05-07 23:54     ` Jason Gunthorpe
2020-05-08  2:19       ` Peter Xu
2020-05-08 12:10         ` Jason Gunthorpe
2020-05-08 14:30           ` Peter Xu
2020-05-08 15:05             ` Jason Gunthorpe
2020-05-08 15:42               ` Alex Williamson
2020-05-08 16:05                 ` Peter Xu
2020-05-08 18:39   ` Peter Xu
2020-05-05 21:54 ` [PATCH v2 2/3] vfio-pci: Fault mmaps to enable vma tracking Alex Williamson
2020-05-07 21:47   ` Peter Xu
2020-05-07 22:03     ` Alex Williamson
2020-05-07 22:22       ` Peter Xu
2020-05-07 23:56         ` Jason Gunthorpe
2020-05-08  2:16           ` Peter Xu
2020-05-08  6:44             ` Jason Wang
2020-05-08 14:27               ` Peter Xu
2020-05-08 12:08             ` Jason Gunthorpe
2020-05-08 14:26               ` Peter Xu
2020-05-05 21:55 ` [PATCH v2 3/3] vfio-pci: Invalidate mmaps and block MMIO access on disabled memory Alex Williamson
2020-05-22  2:39   ` Qian Cai
2020-05-22  4:18     ` Alex Williamson
2020-05-07 21:59 ` [PATCH v2 0/3] vfio-pci: Block user access to disabled device MMIO Peter Xu
2020-05-07 22:34   ` Alex Williamson
2020-05-08  2:31     ` Peter Xu

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