All of lore.kernel.org
 help / color / mirror / Atom feed
From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Zhenzhong Duan <zhenzhong.duan@oracle.com>, linux-kernel@vger.kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Radim Krcmar <rkrcmar@redhat.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Will Deacon <will@kernel.org>
Subject: Re: [PATCH 1/3] KVM: X86: Add "nopvspin" parameter to disable PV spinlocks
Date: Tue, 01 Oct 2019 10:39:05 +0200	[thread overview]
Message-ID: <87eezw3lna.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <aae59646-be5f-6455-a033-ed29861107ce@oracle.com>

Zhenzhong Duan <zhenzhong.duan@oracle.com> writes:

> On 2019/9/30 23:41, Vitaly Kuznetsov wrote:
>> Zhenzhong Duan<zhenzhong.duan@oracle.com>  writes:
>>
>>> There are cases where a guest tries to switch spinlocks to bare metal
>>> behavior (e.g. by setting "xen_nopvspin" on XEN platform and
>>> "hv_nopvspin" on HYPER_V).
>>>
>>> That feature is missed on KVM, add a new parameter "nopvspin" to disable
>>> PV spinlocks for KVM guest.
>>>
>>> This new parameter is also intended to replace "xen_nopvspin" and
>>> "hv_nopvspin" in the future.
>> Any reason to not do it right now? We will probably need to have compat
>> code to support xen_nopvspin/hv_nopvspin too but emit a 'is deprecated'
>> warning.
>
> Sorry the description isn't clear, I'll fix it.
>
> I did the compat work in the other two patches.
> [PATCH 2/3] xen: Mark "xen_nopvspin" parameter obsolete and map it to "nopvspin"
> [PATCH 3/3] x86/hyperv: Mark "hv_nopvspin" parameter obsolete and map it to "nopvspin"
>

For some reason I got CCed only on the first one and moreover, I don't
see e.g PATCH3 on 'linux-hyperv' mailing list.

>>
>>> The global variable pvspin isn't defined as __initdata as it's used at
>>> runtime by XEN guest.
>>>
>>> Refactor the print stuff with pr_* which is preferred.
>> Please do it in a separate patch.
>
> Ok, I'll do that in v2. Thanks for review.

Thanks!

-- 
Vitaly

  reply	other threads:[~2019-10-01  8:39 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-29 12:21 [PATCH 0/3] Add a unified parameter "nopvspin" Zhenzhong Duan
2019-09-29 12:21 ` [PATCH 1/3] KVM: X86: Add "nopvspin" parameter to disable PV spinlocks Zhenzhong Duan
2019-09-30 15:41   ` Vitaly Kuznetsov
2019-10-01  0:36     ` Zhenzhong Duan
2019-10-01  8:39       ` Vitaly Kuznetsov [this message]
2019-10-01  9:47         ` Zhenzhong Duan
2019-10-02 16:47           ` Sean Christopherson
2019-10-03  9:51             ` Zhenzhong Duan
2019-09-29 12:21 ` [PATCH 2/3] xen: Mark "xen_nopvspin" parameter obsolete and map it to "nopvspin" Zhenzhong Duan
2019-09-30 14:25   ` Jürgen Groß
2019-09-29 12:21 ` [PATCH 3/3] x86/hyperv: Mark "hv_nopvspin" " Zhenzhong Duan

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87eezw3lna.fsf@vitty.brq.redhat.com \
    --to=vkuznets@redhat.com \
    --cc=bp@alien8.de \
    --cc=corbet@lwn.net \
    --cc=hpa@zytor.com \
    --cc=jmattson@google.com \
    --cc=joro@8bytes.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=peterz@infradead.org \
    --cc=rkrcmar@redhat.com \
    --cc=sean.j.christopherson@intel.com \
    --cc=tglx@linutronix.de \
    --cc=wanpengli@tencent.com \
    --cc=will@kernel.org \
    --cc=zhenzhong.duan@oracle.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.