From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Gleb Natapov <gleb@redhat.com>
Cc: "<kvm@vger.kernel.org> list" <kvm@vger.kernel.org>,
Alexander Graf <agraf@suse.de>,
kvm-ppc@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
Paolo Bonzini <pbonzini@redhat.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [RFC PATCH 09/11] kvm: simplify processor compat check
Date: Sun, 29 Sep 2013 20:35:16 +0530 [thread overview]
Message-ID: <87siwnbrdf.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <20130929085800.GO17294@redhat.com>
Gleb Natapov <gleb@redhat.com> writes:
> On Sat, Sep 28, 2013 at 09:06:47PM +0530, Aneesh Kumar K.V wrote:
>> Paolo Bonzini <pbonzini@redhat.com> writes:
>>
>> > Il 27/09/2013 15:13, Aneesh Kumar K.V ha scritto:
>> >> Alexander Graf <agraf@suse.de> writes:
>> >>
>> >>> On 27.09.2013, at 12:03, Aneesh Kumar K.V wrote:
>> >>>
>> >>>> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>> >>>
>> >>> Missing patch description.
>> >>>
>> >>>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>> >>>
>> >>> I fail to see how this really simplifies things, but at the end of the
>> >>> day it's Gleb's and Paolo's call.
>> >>
>> >> will do. It avoid calling
>> >>
>> >> for_each_online_cpu(cpu) {
>> >> smp_call_function_single()
>> >>
>> >> on multiple architecture.
>> >
>> > I agree with Alex.
>> >
>> > The current code is not specially awesome; having
>> > kvm_arch_check_processor_compat take an int* disguised as a void* is a
>> > bit ugly indeed.
>> >
>> > However, the API makes sense and tells you that it is being passed as a
>> > callback (to smp_call_function_single in this case).
>>
>> But whether to check on all cpus or not is arch dependent right?.
>> IIUC only x86 and ppc64 need to do that. Also on ppc64 it really
>> depends on whether HV or PR. We need to check on all cpus only if it is
>> HV.
>>
>> >
>> > You are making the API more complicated to use on the arch layer
>> > (because arch maintainers now have to think "do I need to check this on
>> > all online CPUs?") and making the "leaf" POWER code less legible because
>> > it still has the weird void()(void *) calling convention.
>> >
>>
>> IIUC what we wanted to check is to find out whether kvm can run on this
>> system. That is really an arch specific check. So for core kvm the call
>> should be a simple
>>
>> if (kvm_arch_check_process_compat() < 0)
>> error;
> We have that already, just return error from kvm_arch_hardware_setup. This
> is specific processor compatibility check and you are arguing that the
> processor check should be part of kvm_arch_hardware_setup().
What about the success case ?. ie, on arch like arm we do
void kvm_arch_check_processor_compat(void *rtn)
{
*(int *)rtn = 0;
}
for_each_online_cpu(cpu) {
smp_call_function_single(cpu,
kvm_arch_check_processor_compat,
&r, 1);
if (r < 0)
goto out_free_1;
}
There is no need to do that for loop for arm.
The only reason I wanted this patch in the series is to make
kvm_arch_check_processor_compat take additional argument opaque.
I am dropping that requirement in the last patch. Considering
that we have objection to this one, I will drop this patch in
the next posting by rearranging the patches.
-aneesh
next prev parent reply other threads:[~2013-09-29 15:05 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-27 10:03 [RFC PATCH 00/11 Allow PR and HV KVM to coexist in one kernel Aneesh Kumar K.V
2013-09-27 10:03 ` [RFC PATCH 01/11] kvm: powerpc: book3s hv: Fix vcore leak Aneesh Kumar K.V
2013-09-27 11:39 ` Alexander Graf
2013-09-27 10:03 ` [RFC PATCH 02/11] kvm: powerpc: book3s: remove kvmppc_handler_highmem label Aneesh Kumar K.V
2013-09-27 10:03 ` [RFC PATCH 03/11] kvm: powerpc: book3s: move book3s_64_vio_hv.c into the main kernel binary Aneesh Kumar K.V
2013-09-27 10:03 ` [RFC PATCH 04/11] kvm: powerpc: book3s: Add a new config variable CONFIG_KVM_BOOK3S_HV Aneesh Kumar K.V
2013-09-27 11:43 ` Alexander Graf
2013-09-27 12:45 ` Aneesh Kumar K.V
2013-09-27 10:03 ` [RFC PATCH 05/11] kvm: powerpc: book3s: Add kvmppc_ops callback for HV and PR specific operations Aneesh Kumar K.V
2013-09-27 12:04 ` Alexander Graf
2013-09-27 12:52 ` Aneesh Kumar K.V
2013-09-27 10:03 ` [RFC PATCH 06/11] kvm: powerpc: book3s: Add is_hv_enabled to kvmppc_ops Aneesh Kumar K.V
2013-09-27 12:18 ` Alexander Graf
2013-09-27 13:03 ` Aneesh Kumar K.V
2013-09-30 10:09 ` Alexander Graf
2013-09-30 12:56 ` Aneesh Kumar K.V
2013-09-30 14:51 ` Alexander Graf
2013-09-30 16:20 ` Aneesh Kumar K.V
2013-09-30 16:36 ` Alexander Graf
2013-09-27 10:03 ` [RFC PATCH 07/11] kvm: powerpc: book3s: pr: move PR related tracepoints to a separate header Aneesh Kumar K.V
2013-09-27 12:22 ` Alexander Graf
2013-09-27 13:06 ` Aneesh Kumar K.V
2013-09-30 10:02 ` Alexander Graf
2013-09-30 12:57 ` Aneesh Kumar K.V
2013-09-30 14:51 ` Alexander Graf
2013-09-30 15:53 ` Aneesh Kumar K.V
2013-09-30 15:55 ` Alexander Graf
2013-09-27 10:03 ` [RFC PATCH 08/11] kvm: powerpc: book3s: Support building HV and PR KVM as module Aneesh Kumar K.V
2013-09-27 12:25 ` Alexander Graf
2013-09-27 13:08 ` Aneesh Kumar K.V
2013-09-30 10:04 ` Alexander Graf
2013-09-30 12:57 ` Aneesh Kumar K.V
2013-09-27 10:03 ` [RFC PATCH 09/11] kvm: simplify processor compat check Aneesh Kumar K.V
2013-09-27 12:31 ` Alexander Graf
2013-09-27 13:13 ` Aneesh Kumar K.V
2013-09-27 15:14 ` Paolo Bonzini
2013-09-28 15:36 ` Aneesh Kumar K.V
2013-09-29 8:58 ` Gleb Natapov
2013-09-29 15:05 ` Aneesh Kumar K.V [this message]
2013-09-29 15:11 ` Gleb Natapov
2013-09-27 10:03 ` [RFC PATCH 10/11] kvm: powerpc: book3s: Allow the HV and PR selection per virtual machine Aneesh Kumar K.V
2013-09-27 10:03 ` [RFC PATCH 11/11] kvm: powerpc: book3s: Fix module ownership Aneesh Kumar K.V
2013-09-27 10:52 ` [RFC PATCH 00/11 Allow PR and HV KVM to coexist in one kernel Aneesh Kumar K.V
2013-09-30 10:16 ` Alexander Graf
2013-09-30 13:09 ` Aneesh Kumar K.V
2013-09-30 14:54 ` Alexander Graf
2013-10-01 11:26 ` Aneesh Kumar K.V
2013-10-01 11:36 ` Alexander Graf
2013-10-01 11:41 ` Paolo Bonzini
2013-10-01 11:43 ` Alexander Graf
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