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From: Paolo Bonzini <pbonzini@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, vkuznets@redhat.com
Subject: Re: [PATCH 1/2] KVM: KVM-on-hyperv: shorten no-entry section on reenlightenment
Date: Thu, 12 Aug 2021 17:53:17 +0200	[thread overview]
Message-ID: <5e3ddaea-c0f4-f207-de54-5702c970079b@redhat.com> (raw)
In-Reply-To: <20210811180322.GA178399@fuller.cnet>

On 11/08/21 20:03, Marcelo Tosatti wrote:
>          hyperv_stop_tsc_emulation();
> 
>          /* TSC frequency always matches when on Hyper-V */
>          for_each_present_cpu(cpu)
>                  per_cpu(cpu_tsc_khz, cpu) = tsc_khz;
>          kvm_max_guest_tsc_khz = tsc_khz;

Yeah, it's more complicated than this.  The right sequence is:

- update the master clock

- update the TSC page parameters

- stop TSC emulation

There is no need to invalidate the TSC page.

Related to this, after kvm_hv_invalidate_tsc_page the sequence value in 
the Hyper-V TSC page will always be 1, which is wrong.  I'll take a look 
at that too.

Paolo


  reply	other threads:[~2021-08-12 15:53 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-11 10:23 [PATCH 0/2] KVM: x86: abstract locking around pvclock_update_vm_gtod_copy Paolo Bonzini
2021-08-11 10:23 ` [PATCH 1/2] KVM: KVM-on-hyperv: shorten no-entry section on reenlightenment Paolo Bonzini
2021-08-11 18:03   ` Marcelo Tosatti
2021-08-12 15:53     ` Paolo Bonzini [this message]
2021-08-11 10:23 ` [PATCH 2/2] kvm: x86: abstract locking around pvclock_update_vm_gtod_copy Paolo Bonzini

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