[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH v6 03/18] s390x: protvirt: Support unpack facility
From: |
David Hildenbrand |
Subject: |
Re: [PATCH v6 03/18] s390x: protvirt: Support unpack facility |
Date: |
Thu, 5 Mar 2020 15:15:38 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 |
>>>
>>> +static void s390_machine_unprotect(S390CcwMachineState *ms)
>>> +{
>>> + CPUState *t;
>>> +
>>> + if (!ms->pv)
>>> + return;
>>
>> How can this ever happen? g_assert(ms->pv) ?
>
> Currently not, that's only used in the follow up patches with the ballon
> and migration blocker
Even then, why should we unprotect when not protected. That looks wrong
to me and has to be fixed in the other patches,
>
>>
>> Also, i don't see this function getting called from anywhere else except
>> when s390_machine_protect() fails. That looks wrong. This has to be
>> called when going out of PV mode.
>
> Yes, but that's in the diag308 1-4 patch.
The way patches were split up is somewhat sub-optimal for review.
[...]
>>> + break;
>>> + case S390_RESET_PV: /* Subcode 10 */
>>> + subsystem_reset();
>>> + s390_crypto_reset();
>>> +
>>> + CPU_FOREACH(t) {
>>> + if (t == cs) {
>>> + continue;
>>> + }
>>> + run_on_cpu(t, s390_do_cpu_full_reset, RUN_ON_CPU_NULL);
>>> + }
>>> + run_on_cpu(cs, s390_do_cpu_reset, RUN_ON_CPU_NULL);
>>> +
>>> + if (s390_machine_protect(ms)) {
>>> + s390_machine_inject_pv_error(cs);
>>
>> Ah, so it's not an actual exception. BUT: All other guest cpus were
>> reset, can the guest deal with that?
>
> Well, all other CPUs should be stopped for diag308, no?
> Also it's done by the bootloader and not a OS which just stops its cpus
> and goes into protected mode.
>
>>
>> (run_on_cpu(cs, s390_do_cpu_reset, RUN_ON_CPU_NULL) should go after the
>> s390_machine_protect() I assume - the change you had in the other patch)
>
> That's not a good idea, I want to reset before we automatically call the
> UV routines on a reset.
But how can s390_machine_inject_pv_error(cs) be any effective if you
already reset the CPU?
--
Thanks,
David / dhildenb
Re: [PATCH v6 03/18] s390x: protvirt: Support unpack facility, David Hildenbrand, 2020/03/05
Re: [PATCH v6 03/18] s390x: protvirt: Support unpack facility, Christian Borntraeger, 2020/03/06
[PATCH v6 06/18] s390x: protvirt: Inhibit balloon when switching to protected mode, Janosch Frank, 2020/03/04
[PATCH v6 07/18] s390x: protvirt: KVM intercept changes, Janosch Frank, 2020/03/04