search for: virtio_f_use_bus_map

...rtio spec. Since virtio_pci can be > a module, obvious hacks like having xen_arch_setup initialize a dma_ops pointer > exposed by virtio_pci.c is out. Well virtio could probe for xen, it's not a lot of code. > I think the best approach is to have a new feature bit (25 is free), > VIRTIO_F_USE_BUS_MAPPING which indicates that a device really wants to > use the mapping for the bus it is on. A real device would set this, > or it won't work behind an IOMMU. A Xen device would also set this. > > Thoughts? > Rusty. OK and it should then be active even if guest does not ack the...

...rtio spec. Since virtio_pci can be > a module, obvious hacks like having xen_arch_setup initialize a dma_ops pointer > exposed by virtio_pci.c is out. Well virtio could probe for xen, it's not a lot of code. > I think the best approach is to have a new feature bit (25 is free), > VIRTIO_F_USE_BUS_MAPPING which indicates that a device really wants to > use the mapping for the bus it is on. A real device would set this, > or it won't work behind an IOMMU. A Xen device would also set this. > > Thoughts? > Rusty. OK and it should then be active even if guest does not ack the...

...ec. Since virtio_pci can be > a module, obvious hacks like having xen_arch_setup initialize a dma_ops pointer > exposed by virtio_pci.c is out. Xen does expose dma_ops. The trick is knowing when to use it. > > I think the best approach is to have a new feature bit (25 is free), > VIRTIO_F_USE_BUS_MAPPING which indicates that a device really wants to > use the mapping for the bus it is on. A real device would set this, > or it won't work behind an IOMMU. A Xen device would also set this. The devices I care about aren't actually Xen devices. They're devices supplied by QEMU/...

...ec. Since virtio_pci can be > a module, obvious hacks like having xen_arch_setup initialize a dma_ops pointer > exposed by virtio_pci.c is out. Xen does expose dma_ops. The trick is knowing when to use it. > > I think the best approach is to have a new feature bit (25 is free), > VIRTIO_F_USE_BUS_MAPPING which indicates that a device really wants to > use the mapping for the bus it is on. A real device would set this, > or it won't work behind an IOMMU. A Xen device would also set this. The devices I care about aren't actually Xen devices. They're devices supplied by QEMU/...

On Tue, Sep 2, 2014 at 1:53 PM, Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote: > On Mon, 2014-09-01 at 22:55 -0700, Andy Lutomirski wrote: >> >> On x86, at least, I doubt that we'll ever see a physically addressed >> PCI virtio device for which ACPI advertises an IOMMU, since any sane >> hypervisor will just not advertise an IOMMU for the virtio

On Tue, Sep 2, 2014 at 1:53 PM, Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote: > On Mon, 2014-09-01 at 22:55 -0700, Andy Lutomirski wrote: >> >> On x86, at least, I doubt that we'll ever see a physically addressed >> PCI virtio device for which ACPI advertises an IOMMU, since any sane >> hypervisor will just not advertise an IOMMU for the virtio

...ce if Linux virtio Just Worked under Xen, though Xen's IOMMU is outside the virtio spec. Since virtio_pci can be a module, obvious hacks like having xen_arch_setup initialize a dma_ops pointer exposed by virtio_pci.c is out. I think the best approach is to have a new feature bit (25 is free), VIRTIO_F_USE_BUS_MAPPING which indicates that a device really wants to use the mapping for the bus it is on. A real device would set this, or it won't work behind an IOMMU. A Xen device would also set this. Thoughts? Rusty. PS. I cc'd OASIS virtio-dev: it's subscriber only for IP reasons (to subsc...

...rtio could probe for xen, it's not a lot of code. We could, but I think this is going to be a more general problem in future. x86 is heading down the IOMMU path, and they're likely to suffer similarly. >> I think the best approach is to have a new feature bit (25 is free), >> VIRTIO_F_USE_BUS_MAPPING which indicates that a device really wants to >> use the mapping for the bus it is on. A real device would set this, >> or it won't work behind an IOMMU. A Xen device would also set this. >> >> Thoughts? >> Rusty. > > OK and it should then be active ev...

...like having xen_arch_setup initialize a dma_ops pointer >>> exposed by virtio_pci.c is out. >> >> Xen does expose dma_ops. The trick is knowing when to use it. >> >>> >>> I think the best approach is to have a new feature bit (25 is free), >>> VIRTIO_F_USE_BUS_MAPPING which indicates that a device really wants to >>> use the mapping for the bus it is on. A real device would set this, >>> or it won't work behind an IOMMU. A Xen device would also set this. >> >> The devices I care about aren't actually Xen devices. They...

...like having xen_arch_setup initialize a dma_ops pointer >>> exposed by virtio_pci.c is out. >> >> Xen does expose dma_ops. The trick is knowing when to use it. >> >>> >>> I think the best approach is to have a new feature bit (25 is free), >>> VIRTIO_F_USE_BUS_MAPPING which indicates that a device really wants to >>> use the mapping for the bus it is on. A real device would set this, >>> or it won't work behind an IOMMU. A Xen device would also set this. >> >> The devices I care about aren't actually Xen devices. They...

...> a module, obvious hacks like having xen_arch_setup initialize a dma_ops pointer >> exposed by virtio_pci.c is out. > > Xen does expose dma_ops. The trick is knowing when to use it. > >> >> I think the best approach is to have a new feature bit (25 is free), >> VIRTIO_F_USE_BUS_MAPPING which indicates that a device really wants to >> use the mapping for the bus it is on. A real device would set this, >> or it won't work behind an IOMMU. A Xen device would also set this. > > The devices I care about aren't actually Xen devices. They're devices...

...initialize a dma_ops pointer >>>> exposed by virtio_pci.c is out. >>> >>> Xen does expose dma_ops. The trick is knowing when to use it. >>> >>>> >>>> I think the best approach is to have a new feature bit (25 is free), >>>> VIRTIO_F_USE_BUS_MAPPING which indicates that a device really wants to >>>> use the mapping for the bus it is on. A real device would set this, >>>> or it won't work behind an IOMMU. A Xen device would also set this. >>> >>> The devices I care about aren't actually Xe...