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From: Andy Lutomirski <luto@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Maxim Levitsky <mlevitsk@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	kvm list <kvm@vger.kernel.org>, "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>,
	Vitaly Kuznetsov <vkuznets@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>
Subject: Re: [PATCH v2 1/3] KVM: x86: implement KVM_{GET|SET}_TSC_STATE
Date: Thu, 10 Dec 2020 14:01:12 -0800	[thread overview]
Message-ID: <CALCETrXXH5GoaSZwSPy-JFxJ6iMMCj0A=yFFPuyutBh+1imCsQ@mail.gmail.com> (raw)
In-Reply-To: <87360djqve.fsf@nanos.tec.linutronix.de>

On Thu, Dec 10, 2020 at 1:25 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>
> Andy,
>

>
> I'm still convinced that a notification about 'we take a nap' will be
> more robust, less complex and more trivial to backport.

What do you have in mind?  Suppose the host kernel sends the guest an
interrupt on all vCPUs saying "I'm about to take a nap".  What happens
if the guest is busy with IRQs off for a little bit?  Does the host
guarantee the guest a certain about of time to try to get the
interrupt delivered before allowing the host to enter S3?  How about
if the host wants to reboot for a security fix -- how long is a guest
allowed to delay the process?

I'm sure this can all be made to work 99% of time, but I'm a bit
concerned about that last 1%.

--Andy

  reply	other threads:[~2020-12-10 23:06 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
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 [this message]
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

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