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Subject: Re: PR KVM and TM issues
To: Michael Neuling <mikey@neuling.org>, Anton Blanchard <anton@samba.org>,
 Michael Ellerman <mpe@ellerman.id.au>, Paul Mackerras <paulus@samba.org>,
 Benjamin Herrenschmidt <benh@kernel.crashing.org>
References: <20160404164457.539a55f0@kryten> <57021123.6050506@ozlabs.ru>
 <1459768184.3260.14.camel@neuling.org>
Cc: linuxppc-dev@lists.ozlabs.org
From: Alexey Kardashevskiy <aik@ozlabs.ru>
Message-ID: <57036956.60606@ozlabs.ru>
Date: Tue, 5 Apr 2016 17:29:26 +1000
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On 04/04/2016 09:09 PM, Michael Neuling wrote:
> On Mon, 2016-04-04 at 17:00 +1000, Alexey Kardashevskiy wrote:
>> On 04/04/2016 04:44 PM, Anton Blanchard wrote:
>>> Hi,
>>>
>>> I can't get an Ubuntu Wily guest to boot on an Ubuntu Wily host in PR KVM
>>> mode. The kernel in both cases is 4.2. To reproduce:
>>>
>>> wget -N https://cloud-images.ubuntu.com/wily/current/wily-server-cloudimg-ppc64el-disk1.img
>>>
>>> qemu-system-ppc64 -cpu POWER8 -enable-kvm -machine pseries,kvm-type=PR -m 4G -nographic -vga none -drive file=wily-server-cloudimg-ppc64el-disk1.img,if=virtio
>>>
>>> Should TM work inside a PR KVM guest?
>>
>> If I read the kernel code correctly (kvmppc_set_one_reg_hv vs.
>> kvmppc_set_one_reg_pr), no, it should not be expected to work.
>
> What's missing?

I do not know much about TM... SET_ONE_REG interface does not support TM 
registers for PR KVM and stuff which e4e38121507a2 "KVM: PPC: Book3S HV: 
Add transactional memory support" adds (save/restore TM state on guest 
entry/exit) is absent in PR KVM's book3s_rmhandlers.S.


-- 
Alexey