Re: [Qemu-devel] [PATCH v4] ppc/spapr: Implement H_RANDOM hypercall in QEMU

[David Gibson <david@gibson.dropbear.id.au>]

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On Thu, Sep 17, 2015 at 10:49:41AM +0200, Thomas Huth wrote:
> The PAPR interface defines a hypercall to pass high-quality
> hardware generated random numbers to guests. Recent kernels can
> already provide this hypercall to the guest if the right hardware
> random number generator is available. But in case the user wants
> to use another source like EGD, or QEMU is running with an older
> kernel, we should also have this call in QEMU, so that guests that
> do not support virtio-rng yet can get good random numbers, too.
> 
> This patch now adds a new pseudo-device to QEMU that either
> directly provides this hypercall to the guest or is able to
> enable the in-kernel hypercall if available. The in-kernel
> hypercall can be enabled with the use-kvm property, e.g.:
> 
>  qemu-system-ppc64 -device spapr-rng,use-kvm=true
> 
> For handling the hypercall in QEMU instead, a "RngBackend" is
> required since the hypercall should provide "good" random data
> instead of pseudo-random (like from a "simple" library function
> like rand() or g_random_int()). Since there are multiple RngBackends
> available, the user must select an appropriate back-end via the
> "rng" property of the device, e.g.:
> 
>  qemu-system-ppc64 -object rng-random,filename=/dev/hwrng,id=gid0 \
>                    -device spapr-rng,rng=gid0 ...
> 
> See http://wiki.qemu-project.org/Features-Done/VirtIORNG for
> other example of specifying RngBackends.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>

Thanks, applied to spapr-next.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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