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x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: fkbiap8mwzbfg4jsgdxdjyug4x33pbga X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 9E7BBC0005 X-Rspam-User: X-HE-Tag: 1708635168-162621 X-HE-Meta: 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 N0OFniRT Lfpup13bH5JqplB2JbgZJ6AagmqtzptBTJWsqnQFJQrfVkaMNmyvYjlIAvwmpSIDWRZYm9040cwvspGA0Rdi/MxjbLZhQFUHbyFXoyGotRVILHFRkARFVnq1EhlkmJTvfPEjMuC3V63nbwpeO+3wSvS1YxQ6sUulxeVQKDCmJbG/mM4ca1Jj1zz6DUafDyUMo+bHwkpaelKrqRWmI4sYNipkjkQ78Sne7ipu2DfwMqMzclX/3V1OhbbGQOtl1Zkj+XKb9XKKAePbSnKy0Yc5Nfb7m/Gik4VQRXWbmBp57LiU2eacD4KBE7Zg5xTLgSF9JJrp4bdJajKX1DStYyXBzLTVXqJO9KBZViMrGHo5znGaJCLXrPUDZ2g4Bz5X8QF0KnLqgXR+gDzrYs43/gVoH8Tzdw081E69h/IdBpeK3vvvc1/t+RGEo9d/DO+oo5IwYjubvbdvOOurikq0HZ7Pi8xN+k+cCR7cx0h3qGRu9SmH9ThrKBEhe8mondAdMXhxa18pQ4c8Pb3SB7h0p8V4/7M8N+A== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 20 Feb 2024 12:59:26 +0530 wrote: > From: Ankit Agrawal > > The VM_ALLOW_ANY_UNCACHED flag is implemented for ARM64, > allowing KVM stage 2 device mapping attributes to use Normal-NC > rather than DEVICE_nGnRE, which allows guest mappings > supporting combining attributes (WC). ARM does not architecturally > guarantee this is safe, and indeed some MMIO regions like the GICv2 > VCPU interface can trigger uncontained faults if Normal-NC is used. > > To safely use VFIO in KVM the platform must guarantee full safety > in the guest where no action taken against a MMIO mapping can > trigger an uncontained failure. We belive that most VFIO PCI > platforms support this for both mapping types, at least in common > flows, based on some expectations of how PCI IP is integrated. So > make vfio-pci set the VM_ALLOW_ANY_UNCACHED flag. > > Suggested-by: Catalin Marinas > Acked-by: Jason Gunthorpe > Acked-by: Catalin Marinas > Reviewed-by: David Hildenbrand > Signed-off-by: Ankit Agrawal > --- > drivers/vfio/pci/vfio_pci_core.c | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > > diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c > index 1cbc990d42e0..c93bea18fc4b 100644 > --- a/drivers/vfio/pci/vfio_pci_core.c > +++ b/drivers/vfio/pci/vfio_pci_core.c > @@ -1862,8 +1862,24 @@ int vfio_pci_core_mmap(struct vfio_device *core_vdev, struct vm_area_struct *vma > /* > * See remap_pfn_range(), called from vfio_pci_fault() but we can't > * change vm_flags within the fault handler. Set them now. > + * > + * VM_ALLOW_ANY_UNCACHED: The VMA flag is implemented for ARM64, > + * allowing KVM stage 2 device mapping attributes to use Normal-NC > + * rather than DEVICE_nGnRE, which allows guest mappings > + * supporting combining attributes (WC). ARM does not > + * architecturally guarantee this is safe, and indeed some MMIO > + * regions like the GICv2 VCPU interface can trigger uncontained > + * faults if Normal-NC is used. > + * > + * To safely use VFIO in KVM the platform must guarantee full > + * safety in the guest where no action taken against a MMIO > + * mapping can trigger an uncontained failure. We belive that > + * most VFIO PCI platforms support this for both mapping types, > + * at least in common flows, based on some expectations of how > + * PCI IP is integrated. So set VM_ALLOW_ANY_UNCACHED in VMA flags. > */ > - vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP); > + vm_flags_set(vma, VM_ALLOW_ANY_UNCACHED | VM_IO | VM_PFNMAP | > + VM_DONTEXPAND | VM_DONTDUMP); > vma->vm_ops = &vfio_pci_mmap_ops; > > return 0; Acked-by: Alex Williamson