linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
	Maxim Levitsky <mlevitsk@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Jim Mattson <jmattson@google.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	"open list\:KERNEL SELFTEST FRAMEWORK" 
	<linux-kselftest@vger.kernel.org>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	open list <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	"maintainer\:X86 ARCHITECTURE \(32-BIT AND 64-BIT\)"
	<x86@kernel.org>, Joerg Roedel <joro@8bytes.org>,
	Borislav Petkov <bp@alien8.de>, Shuah Khan <shuah@kernel.org>,
	Andrew Jones <drjones@redhat.com>,
	Oliver Upton <oupton@google.com>,
	"open list\:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	kvm@vger.kernel.org
Subject: Re: [PATCH v2 1/3] KVM: x86: implement KVM_{GET|SET}_TSC_STATE
Date: Thu, 10 Dec 2020 21:20:45 +0100	[thread overview]
Message-ID: <87blf1jtuq.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201210130131.GP2414@hirez.programming.kicks-ass.net>

On Thu, Dec 10 2020 at 14:01, Peter Zijlstra wrote:
> On Thu, Dec 10, 2020 at 01:22:02PM +0100, Paolo Bonzini wrote:
>> On 10/12/20 13:14, Peter Zijlstra wrote:
>> > On Thu, Dec 10, 2020 at 12:42:36PM +0100, Paolo Bonzini wrote:
>> > > On 07/12/20 18:41, Thomas Gleixner wrote:
>> > > > Right this happens still occasionally, but for quite some time this is
>> > > > 100% firmware sillyness and not a fundamental property of the hardware
>> > > > anymore.
>> > > 
>> > > It's still a fundamental property of old hardware.  Last time I tried to
>> > > kill support for processors earlier than Core 2, I had to revert it. That's
>> > > older than Nehalem.
>> > 
>> > Core2 doesn't use TSC for timekeeping anyway. KVM shouldn't either.
>> 
>> On Core2, KVM guests pass TSC through kvmclock in order to get something
>> usable and not incredibly slow.
>
> Which is incredibly wrong.

Core2 is really not something which should prevent making all of this
correct and robust. That'd be not only wrong, that'd be outright insane.

Thanks,

        tglx

  reply	other threads:[~2020-12-10 20:21 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-03 17:11 [PATCH v2 0/3] RFC: Precise TSC migration Maxim Levitsky
2020-12-03 17:11 ` [PATCH v2 1/3] KVM: x86: implement KVM_{GET|SET}_TSC_STATE Maxim Levitsky
2020-12-06 16:19   ` Thomas Gleixner
2020-12-07 12:16     ` Maxim Levitsky
2020-12-07 13:16       ` Vitaly Kuznetsov
2020-12-07 17:41         ` Thomas Gleixner
2020-12-08  9:48           ` Peter Zijlstra
2020-12-10 11:42           ` Paolo Bonzini
2020-12-10 12:14             ` Peter Zijlstra
2020-12-10 12:22               ` Paolo Bonzini
2020-12-10 13:01                 ` Peter Zijlstra
2020-12-10 20:20                   ` Thomas Gleixner [this message]
2020-12-07 16:38       ` Thomas Gleixner
2020-12-07 16:53         ` Andy Lutomirski
2020-12-07 17:00           ` Maxim Levitsky
2020-12-07 18:04             ` Andy Lutomirski
2020-12-07 23:11               ` Marcelo Tosatti
2020-12-08 17:43                 ` Andy Lutomirski
2020-12-08 19:24                   ` Thomas Gleixner
2020-12-08 20:32                     ` Andy Lutomirski
2020-12-09  0:19                       ` Thomas Gleixner
2020-12-09  4:08                         ` Andy Lutomirski
2020-12-09 10:14                           ` Thomas Gleixner
2020-12-10 23:42                             ` Andy Lutomirski
2020-12-08 11:24               ` Maxim Levitsky
2020-12-08  9:35         ` Peter Zijlstra
2020-12-07 23:34     ` Marcelo Tosatti
2020-12-07 17:29   ` Oliver Upton
2020-12-08 11:13     ` Maxim Levitsky
2020-12-08 15:57       ` Oliver Upton
2020-12-08 15:58         ` Oliver Upton
2020-12-08 17:10           ` Maxim Levitsky
2020-12-08 16:40       ` Thomas Gleixner
2020-12-08 17:08         ` Maxim Levitsky
2020-12-10 11:48           ` Paolo Bonzini
2020-12-10 14:25             ` Maxim Levitsky
2020-12-07 23:29   ` Marcelo Tosatti
2020-12-08 14:50     ` Maxim Levitsky
2020-12-08 16:02       ` Thomas Gleixner
2020-12-08 16:25         ` Maxim Levitsky
2020-12-08 17:33           ` Andy Lutomirski
2020-12-08 21:25             ` Thomas Gleixner
2020-12-08 18:12           ` Marcelo Tosatti
2020-12-08 21:35             ` Thomas Gleixner
2020-12-08 21:20           ` Thomas Gleixner
2020-12-10 11:48             ` Paolo Bonzini
2020-12-10 14:52               ` Maxim Levitsky
2020-12-10 15:16                 ` Andy Lutomirski
2020-12-10 17:59                   ` Oliver Upton
2020-12-10 18:05                     ` Paolo Bonzini
2020-12-10 18:13                       ` Oliver Upton
2020-12-10 21:25                   ` Thomas Gleixner
2020-12-10 22:01                     ` Andy Lutomirski
2020-12-10 22:28                       ` Thomas Gleixner
2020-12-10 23:19                         ` Andy Lutomirski
2020-12-11  0:03                           ` Thomas Gleixner
2020-12-08 18:11         ` Marcelo Tosatti
2020-12-08 21:33           ` Thomas Gleixner
2020-12-09 16:34             ` Marcelo Tosatti
2020-12-09 20:58               ` Thomas Gleixner
2020-12-10 15:26                 ` Marcelo Tosatti
2020-12-10 21:48                   ` Thomas Gleixner
2020-12-11  0:27                     ` Marcelo Tosatti
2020-12-11 13:30                       ` Thomas Gleixner
2020-12-11 14:18                         ` Marcelo Tosatti
2020-12-11 21:04                           ` Thomas Gleixner
2020-12-11 21:59                             ` Paolo Bonzini
2020-12-12 13:03                               ` Thomas Gleixner
2020-12-15 10:59                               ` Marcelo Tosatti
2020-12-15 16:55                                 ` Andy Lutomirski
2020-12-15 22:34                                 ` Thomas Gleixner
2020-12-11 13:37                       ` Paolo Bonzini
2020-12-08 17:35       ` Marcelo Tosatti
2020-12-03 17:11 ` [PATCH v2 2/3] KVM: x86: introduce KVM_X86_QUIRK_TSC_HOST_ACCESS Maxim Levitsky
2020-12-03 17:11 ` [PATCH v2 3/3] kvm/selftests: update tsc_msrs_test to cover KVM_X86_QUIRK_TSC_HOST_ACCESS Maxim Levitsky
2020-12-07 23:16 ` [PATCH v2 0/3] RFC: Precise TSC migration Marcelo Tosatti
2020-12-10 11:48 ` Paolo Bonzini

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=87blf1jtuq.fsf@nanos.tec.linutronix.de \
    --to=tglx@linutronix.de \
    --cc=bp@alien8.de \
    --cc=corbet@lwn.net \
    --cc=drjones@redhat.com \
    --cc=hpa@zytor.com \
    --cc=jmattson@google.com \
    --cc=joro@8bytes.org \
    --cc=kvm@vger.kernel.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=mlevitsk@redhat.com \
    --cc=mtosatti@redhat.com \
    --cc=oupton@google.com \
    --cc=pbonzini@redhat.com \
    --cc=peterz@infradead.org \
    --cc=sean.j.christopherson@intel.com \
    --cc=shuah@kernel.org \
    --cc=vkuznets@redhat.com \
    --cc=wanpengli@tencent.com \
    --cc=x86@kernel.org \
    /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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).