Re: [Qemu-devel] [PATCH v2 1/2] spapr: Add support for hwrng when available

[Thomas Huth <thuth@redhat.com>]

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On 01/09/15 02:38, David Gibson wrote:
> On Mon, Aug 31, 2015 at 08:46:01PM +0200, Thomas Huth wrote:
>> From: Michael Ellerman <michael@ellerman.id.au>
>>
>> Some powerpc systems have support for a hardware random number generator
>> (hwrng). If such a hwrng is present the host kernel can provide access
>> to it via the H_RANDOM hcall.
>>
>> The kernel advertises the presence of a hwrng with the KVM_CAP_PPC_HWRNG
>> capability. If this is detected we add the appropriate device tree bits
>> to advertise the presence of the hwrng to the guest kernel.
>>
>> Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
>> [thuth: Refreshed patch so it applies to QEMU master branch]
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
> 
> So, I'm confused by one thing.
> 
> I thought new kernel handled hcalls were supposed to be disabled by
> default, but I don't see any calls to kvmppc_enable_hcall() to turn on
> H_RANDOM.

Michael's patch was from 2013, the kvmppc_enable_hcall() stuff seems to
be from 2014 ... so the enablement is likely missing in this patch,
indeed. I didn't test the in-kernel hypercall yet, just my QEMU
implementation so far, that's why I did not notice this yet.

Michael, do you want to rework your patch? Or shall I add an additional
enablement patch to my queue?

 Thomas



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