linux-kernel - Re: [PATCH v2] KVM: x86: PMU Event Filter

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Message-ID: <8c0502f4-64eb-3d34-1d76-a313b8f2f37a@redhat.com>
Date:   Thu, 11 Jul 2019 19:12:17 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Eric Hankland <ehankland@...gle.com>
Cc:     Wei Wang <wei.w.wang@...el.com>, rkrcmar@...hat.com,
        linux-kernel@...r.kernel.org,
        Stephane Eranian <eranian@...gle.com>, kvm@...r.kernel.org
Subject: Re: [PATCH v2] KVM: x86: PMU Event Filter

On 11/07/19 19:04, Eric Hankland wrote:
> Thanks for your help. The "type"->"action" change and constant
> renaming sound good to me.

Good!  Another thing, synchronize_rcu is a bit slow for something that
runs whenever a VM starts.  KVM generally uses srcu instead (kvm->srcu
for things that change really rarely, kvm->irq_srcu for things that
change a bit more often).

Paolo

> On Thu, Jul 11, 2019 at 4:58 AM Paolo Bonzini <pbonzini@...hat.com> wrote:
>>
>> On 11/07/19 03:25, Eric Hankland wrote:
>>> - Add a VM ioctl that can control which events the guest can monitor.
>>
>> ... and finally:
>>
>> - the patch whitespace is damaged
>>
>> - the filter is leaked when the VM is destroyed
>>
>> - kmalloc(GFP_KERNEL_ACCOUNT) is preferrable to vmalloc because it
>> accounts memory to the VM correctly.
>>
>> Since this is your first submission, I have fixed up everything.
>>
>> Paolo