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From: Matthew Rosato <mjrosato@linux.ibm.com>
To: Niklas Schnelle <schnelle@linux.ibm.com>,
	Bjorn Helgaas <helgaas@kernel.org>,
	Christoph Hellwig <hch@lst.de>,
	Alexandra Winter <wintera@linux.ibm.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Gerd Bayer <gbayer@linux.ibm.com>, Jason Gunthorpe <jgg@ziepe.ca>,
	Thorsten Winkler <twinkler@linux.ibm.com>,
	Bjorn Helgaas <bhelgaas@google.com>
Cc: Julian Ruess <julianr@linux.ibm.com>,
	Halil Pasic <pasic@linux.ibm.com>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Sven Schnelle <svens@linux.ibm.com>,
	Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, linux-pci@vger.kernel.org
Subject: Re: [PATCH v7 1/3] s390/pci: Fix s390_mmio_read/write syscall page fault handling
Date: Fri, 28 Feb 2025 16:56:35 -0500	[thread overview]
Message-ID: <8cff6617-634c-4e10-bd1d-7719edf484ea@linux.ibm.com> (raw)
In-Reply-To: <20250226-vfio_pci_mmap-v7-1-c5c0f1d26efd@linux.ibm.com>

On 2/26/25 7:07 AM, Niklas Schnelle wrote:
> The s390 MMIO syscalls when using the classic PCI instructions do not
> cause a page fault when follow_pfnmap_start() fails due to the page not
> being present. Besides being a general deficiency this breaks vfio-pci's
> mmap() handling once VFIO_PCI_MMAP gets enabled as this lazily maps on
> first access. Fix this by following a failed follow_pfnmap_start() with
> fixup_user_page() and retrying the follow_pfnmap_start(). Also fix
> a VM_READ vs VM_WRITE mixup in the read syscall.
> 
> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>

  reply	other threads:[~2025-02-28 21:56 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-02-26 12:07 [PATCH v7 0/3] vfio/pci: s390: Fix issues preventing VFIO_PCI_MMAP=y for s390 and enable it Niklas Schnelle
2025-02-26 12:07 ` [PATCH v7 1/3] s390/pci: Fix s390_mmio_read/write syscall page fault handling Niklas Schnelle
2025-02-28 21:56   ` Matthew Rosato [this message]
2025-02-26 12:07 ` [PATCH v7 2/3] PCI: s390: Introduce pdev->non_mappable_bars and replace VFIO_PCI_MMAP Niklas Schnelle
2025-02-26 12:07 ` [PATCH v7 3/3] PCI: s390: Support mmap() of PCI resources except for ISM devices Niklas Schnelle
2025-03-04 22:59 ` [PATCH v7 0/3] vfio/pci: s390: Fix issues preventing VFIO_PCI_MMAP=y for s390 and enable it Bjorn Helgaas

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