Message-ID: <4BBEFA3B.8070609@redhat.com>
Date: Fri, 09 Apr 2010 12:58:19 +0300
From: Avi Kivity <avi@redhat.com>
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To: Greg KH <gregkh@suse.de>
CC: Tom Lyon <pugs@lyon-about.com>, kvm@vger.kernel.org,
       linux-kernel@vger.kernel.org, "Hans J. Koch" <hjk@linutronix.de>
Subject: Re: [PATCH 0/1] uio_pci_generic: extensions to allow access for	non-privileged
 processes
References: <201003311708.38961.pugs@lyon-about.com> <201004010906.47321.pugs@lyon-about.com> <4BB4C591.8000102@redhat.com> <201004011224.45336.pugs@lyon-about.com> <4BB59217.90102@redhat.com> <20100402170515.GA32579@suse.de>
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On 04/02/2010 08:05 PM, Greg KH wrote:
>
>> Currently kvm does device assignment with its own code, I'd like to unify
>> it with uio, not split it off.
>>
>> Separate notifications for msi-x interrupts are just as useful for uio as
>> they are for kvm.
>>      
> I agree, there should not be a difference here for KVM vs. the "normal"
> version.
>    

Just so you know what you got into, here are the kvm requirements:

- msi interrupts delivered via eventfd (these allow us to inject 
interrupts from uio to a guest without going through userspace)
- nonlinear iommu mapping (i.e. map discontiguous ranges of the device 
address space into ranges of the virtual address space)
- dynamic iommu mapping (support guest memory hotplug)
- unprivileged operation once an admin has assigned a device (my 
preferred implementation is to have all operations go through an fd, 
which can be passed via SCM_RIGHTS from a privileged application that 
opens the file)
- access to all config space, but BARs must be translated so userspace 
cannot attack the host
- some mechanism which allows us to affine device interrupts with their 
target vcpus (eventually, this is vague)
- anything mst might add
- a pony

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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