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Re: [Qemu-devel] [Xen-devel] [RFC PATCH 0/4] Qemu: Add Xen vIOMMU suppor
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [Xen-devel] [RFC PATCH 0/4] Qemu: Add Xen vIOMMU support |
Date: |
Mon, 20 Mar 2017 15:35:55 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 |
On 20/03/2017 15:17, Roger Pau Monné wrote:
>>> 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).
Not necessarily, you only need x2APIC support for that in the local APIC
emulation. The MSI hypercalls (similar to KVM's MSI ioctls) can be
extended to accept x2APIC VCPU ids.
Paolo
- 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