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Re: [Qemu-devel] [Xen-devel] [RFC PATCH 0/4] Qemu: Add Xen vIOMMU suppor
Roger Pau Monné
Re: [Qemu-devel] [Xen-devel] [RFC PATCH 0/4] Qemu: Add Xen vIOMMU support
Mon, 20 Mar 2017 14:17:27 +0000
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
- Re: [Qemu-devel] [RFC PATCH 1/4] I440: Allow adding sysbus devices with -device on I440, (continued)
- [Qemu-devel] [RFC PATCH 3/4] xen-pt: bind/unbind interrupt remapping format MSI, Lan Tianyu, 2017/03/17
- [Qemu-devel] [RFC PATCH 2/4] Xen: add a dummy vIOMMU to create/destroy vIOMMU in Xen, Lan Tianyu, 2017/03/17
- [Qemu-devel] [RFC PATCH 4/4] msi: taking interrupt format into consideration during judging a pirq is binded with a event channel, Lan Tianyu, 2017/03/17
- Re: [Qemu-devel] [RFC PATCH 0/4] Qemu: Add Xen vIOMMU support, no-reply, 2017/03/17
- Re: [Qemu-devel] [RFC PATCH 0/4] Qemu: Add Xen vIOMMU support, Paolo Bonzini, 2017/03/17