From: Paolo Bonzini <pbonzini@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>, kvm@vger.kernel.org
Cc: Sean Christopherson <seanjc@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH 2/4] KVM: x86: hyper-v: Prevent using not-yet-updated TSC page by secondary CPUs
Date: Mon, 15 Mar 2021 17:23:39 +0100 [thread overview]
Message-ID: <92bccdca-b6bb-5c09-c5a1-5c75e5a3887d@redhat.com> (raw)
In-Reply-To: <87im5s8l9g.fsf@vitty.brq.redhat.com>
On 15/03/21 16:55, Vitaly Kuznetsov wrote:
>> I think we should instead write 0 to the page in kvm_gen_update_masterclock.
>
> We can do that but we will also need to invalidate
> hv->tsc_ref.tsc_sequence to prevent MSR based clocksource
> (HV_X64_MSR_TIME_REF_COUNT -> get_time_ref_counter()) from using stale
> hv->tsc_ref.tsc_scale/tsc_offset values (in case we had them
> calculated).
Yes, we're talking about the same thing (invalidating tsc_sequence is
done by writing 0 to it).
Paolo
> Also, we can't really disable TSC page for nested scenario when guest
> opted for reenlightenment (PATCH4) but we're not going to update the
> page anyway so there's not much different.
>
next prev parent reply other threads:[~2021-03-15 16:24 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-15 14:37 [PATCH 0/4] KVM: x86: hyper-v: TSC page fixes Vitaly Kuznetsov
2021-03-15 14:37 ` [PATCH 1/4] KVM: x86: hyper-v: Limit guest to writing zero to HV_X64_MSR_TSC_EMULATION_STATUS Vitaly Kuznetsov
2021-03-15 14:37 ` [PATCH 2/4] KVM: x86: hyper-v: Prevent using not-yet-updated TSC page by secondary CPUs Vitaly Kuznetsov
2021-03-15 15:45 ` Paolo Bonzini
2021-03-15 15:55 ` Vitaly Kuznetsov
2021-03-15 16:23 ` Paolo Bonzini [this message]
2021-03-16 12:29 ` Vitaly Kuznetsov
2021-03-15 14:37 ` [PATCH 3/4] KVM: x86: hyper-v: Track Hyper-V TSC page status Vitaly Kuznetsov
2021-03-15 15:15 ` Sean Christopherson
2021-03-15 15:34 ` Vitaly Kuznetsov
2021-03-16 12:24 ` Vitaly Kuznetsov
2021-03-16 15:20 ` Sean Christopherson
2021-03-15 14:37 ` [PATCH 4/4] KVM: x86: hyper-v: Don't touch TSC page values when guest opted for re-enlightenment Vitaly Kuznetsov
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