[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC PATCH 0/4] Qemu: Add Xen vIOMMU support
On Mon, Mar 20, 2017 at 12:38:41PM +0100, Paolo Bonzini wrote: > > > On 20/03/2017 03:40, Lan Tianyu wrote: > >>> Xen only supports emulated I440 and so we enable vIOMMU with emulated > >>> I440 chipset. This works on Linux and Windows guest. > >> Any plans to change this? Why is Xen not able to use Q35 with Intel > >> IOMMU, with only special hooks for interrupt remapping? > >> > >> Paolo > >> > > Hi Paolo: > > Thanks for review. For Xen side, we won't reuse Intel IOMMU device model > > in Qemu and create counterpart in Xen hypervisor. The reasons are > > 1) Avoid round trips between Qemu and Xen hypervisor > > 2) Ease of integration with the rest part of the hypervisor(vIOAPIC, > > vMSI and so on). > > Fair enough, though I'd be worried about increasing the attack surface > of the hypervisor. For KVM, for example, IOMMU emulation requires using > the "split irqchip" feature to move the PIC and IOAPIC out of the kernel > and back to QEMU. Yes, that's right, we are increasing the surface of attack. But Xen also needs it in order to support APIC IDs > 255 on PVH guests (that have a local APIC but no QEMU). Roger. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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