From: Paolo Bonzini <pbonzini@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>, Oliver Upton <oupton@google.com>
Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
Sean Christopherson <seanjc@google.com>,
Marc Zyngier <maz@kernel.org>, Peter Shier <pshier@google.com>,
Jim Mattson <jmattson@google.com>,
David Matlack <dmatlack@google.com>,
Ricardo Koller <ricarkol@google.com>,
Jing Zhang <jingzhangos@google.com>,
Raghavendra Rao Anata <rananta@google.com>,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
linux-arm-kernel@lists.infradead.org,
Andrew Jones <drjones@redhat.com>, Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [PATCH v8 7/7] KVM: x86: Expose TSC offset controls to userspace
Date: Fri, 1 Oct 2021 11:17:33 +0200 [thread overview]
Message-ID: <48151d08-ee29-2b98-b6e1-f3c8a1ff26bc@redhat.com> (raw)
In-Reply-To: <20210930191416.GA19068@fuller.cnet>
On 30/09/21 21:14, Marcelo Tosatti wrote:
>> + new_off_n = t_0 + off_n + (k_1 - k_0) * freq - t_1
> Hi Oliver,
>
> This won't advance the TSC values themselves, right?
Why not? It affects the TSC offset in the vmcs, so the TSC in the VM is
advanced too.
Paolo
> This (advancing the TSC values by the realtime elapsed time) would be
> awesome because TSC clock_gettime() vdso is faster, and some
> applications prefer to just read from TSC directly.
> See "x86: kvmguest: use TSC clocksource if invariant TSC is exposed".
>
> The advancement with this patchset only applies to kvmclock.
>
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>, Oliver Upton <oupton@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
kvm@vger.kernel.org, Will Deacon <will@kernel.org>,
Peter Shier <pshier@google.com>, Marc Zyngier <maz@kernel.org>,
David Matlack <dmatlack@google.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
Jim Mattson <jmattson@google.com>
Subject: Re: [PATCH v8 7/7] KVM: x86: Expose TSC offset controls to userspace
Date: Fri, 1 Oct 2021 11:17:33 +0200 [thread overview]
Message-ID: <48151d08-ee29-2b98-b6e1-f3c8a1ff26bc@redhat.com> (raw)
In-Reply-To: <20210930191416.GA19068@fuller.cnet>
On 30/09/21 21:14, Marcelo Tosatti wrote:
>> + new_off_n = t_0 + off_n + (k_1 - k_0) * freq - t_1
> Hi Oliver,
>
> This won't advance the TSC values themselves, right?
Why not? It affects the TSC offset in the vmcs, so the TSC in the VM is
advanced too.
Paolo
> This (advancing the TSC values by the realtime elapsed time) would be
> awesome because TSC clock_gettime() vdso is faster, and some
> applications prefer to just read from TSC directly.
> See "x86: kvmguest: use TSC clocksource if invariant TSC is exposed".
>
> The advancement with this patchset only applies to kvmclock.
>
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>, Oliver Upton <oupton@google.com>
Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
Sean Christopherson <seanjc@google.com>,
Marc Zyngier <maz@kernel.org>, Peter Shier <pshier@google.com>,
Jim Mattson <jmattson@google.com>,
David Matlack <dmatlack@google.com>,
Ricardo Koller <ricarkol@google.com>,
Jing Zhang <jingzhangos@google.com>,
Raghavendra Rao Anata <rananta@google.com>,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
linux-arm-kernel@lists.infradead.org,
Andrew Jones <drjones@redhat.com>, Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [PATCH v8 7/7] KVM: x86: Expose TSC offset controls to userspace
Date: Fri, 1 Oct 2021 11:17:33 +0200 [thread overview]
Message-ID: <48151d08-ee29-2b98-b6e1-f3c8a1ff26bc@redhat.com> (raw)
In-Reply-To: <20210930191416.GA19068@fuller.cnet>
On 30/09/21 21:14, Marcelo Tosatti wrote:
>> + new_off_n = t_0 + off_n + (k_1 - k_0) * freq - t_1
> Hi Oliver,
>
> This won't advance the TSC values themselves, right?
Why not? It affects the TSC offset in the vmcs, so the TSC in the VM is
advanced too.
Paolo
> This (advancing the TSC values by the realtime elapsed time) would be
> awesome because TSC clock_gettime() vdso is faster, and some
> applications prefer to just read from TSC directly.
> See "x86: kvmguest: use TSC clocksource if invariant TSC is exposed".
>
> The advancement with this patchset only applies to kvmclock.
>
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-10-01 9:17 UTC|newest]
Thread overview: 113+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-16 18:15 [PATCH v8 0/7] KVM: x86: Add idempotent controls for migrating system counter state Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-16 18:15 ` [PATCH v8 1/7] kvm: x86: abstract locking around pvclock_update_vm_gtod_copy Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-16 18:15 ` [PATCH v8 2/7] KVM: x86: extract KVM_GET_CLOCK/KVM_SET_CLOCK to separate functions Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-16 18:15 ` [PATCH v8 3/7] KVM: x86: Fix potential race in KVM_GET_CLOCK Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-29 13:33 ` Marcelo Tosatti
2021-09-29 13:33 ` Marcelo Tosatti
2021-09-29 13:33 ` Marcelo Tosatti
2021-09-16 18:15 ` [PATCH v8 4/7] KVM: x86: Report host tsc and realtime values " Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-28 18:53 ` Marcelo Tosatti
2021-09-28 18:53 ` Marcelo Tosatti
2021-09-28 18:53 ` Marcelo Tosatti
2021-09-29 11:20 ` Paolo Bonzini
2021-09-29 11:20 ` Paolo Bonzini
2021-09-29 11:20 ` Paolo Bonzini
2021-09-29 18:56 ` Marcelo Tosatti
2021-09-29 18:56 ` Marcelo Tosatti
2021-09-29 18:56 ` Marcelo Tosatti
2021-09-30 19:21 ` Marcelo Tosatti
2021-09-30 19:21 ` Marcelo Tosatti
2021-09-30 19:21 ` Marcelo Tosatti
2021-09-30 23:02 ` Thomas Gleixner
2021-09-30 23:02 ` Thomas Gleixner
2021-09-30 23:02 ` Thomas Gleixner
2021-10-01 12:05 ` Marcelo Tosatti
2021-10-01 12:05 ` Marcelo Tosatti
2021-10-01 12:05 ` Marcelo Tosatti
2021-10-01 12:10 ` Marcelo Tosatti
2021-10-01 12:10 ` Marcelo Tosatti
2021-10-01 12:10 ` Marcelo Tosatti
2021-10-01 19:59 ` Thomas Gleixner
2021-10-01 19:59 ` Thomas Gleixner
2021-10-01 19:59 ` Thomas Gleixner
2021-10-01 21:03 ` Oliver Upton
2021-10-01 21:03 ` Oliver Upton
2021-10-01 21:03 ` Oliver Upton
2021-10-01 14:17 ` Paolo Bonzini
2021-10-01 14:17 ` Paolo Bonzini
2021-10-01 14:17 ` Paolo Bonzini
2021-10-01 14:39 ` Paolo Bonzini
2021-10-01 14:39 ` Paolo Bonzini
2021-10-01 14:39 ` Paolo Bonzini
2021-10-01 14:41 ` Paolo Bonzini
2021-10-01 14:41 ` Paolo Bonzini
2021-10-01 14:41 ` Paolo Bonzini
2021-10-01 15:39 ` Oliver Upton
2021-10-01 15:39 ` Oliver Upton
2021-10-01 15:39 ` Oliver Upton
2021-10-01 16:42 ` Paolo Bonzini
2021-10-01 16:42 ` Paolo Bonzini
2021-10-01 16:42 ` Paolo Bonzini
2024-01-17 14:28 ` David Woodhouse
2024-01-17 14:28 ` David Woodhouse
2021-09-16 18:15 ` [PATCH v8 5/7] kvm: x86: protect masterclock with a seqcount Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-24 16:42 ` Paolo Bonzini
2021-09-24 16:42 ` Paolo Bonzini
2021-09-24 16:42 ` Paolo Bonzini
2021-09-30 17:51 ` Marcelo Tosatti
2021-09-30 17:51 ` Marcelo Tosatti
2021-09-30 17:51 ` Marcelo Tosatti
2021-10-01 16:48 ` Paolo Bonzini
2021-10-01 16:48 ` Paolo Bonzini
2021-10-01 16:48 ` Paolo Bonzini
2021-09-16 18:15 ` [PATCH v8 6/7] KVM: x86: Refactor tsc synchronization code Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-16 18:15 ` [PATCH v8 7/7] KVM: x86: Expose TSC offset controls to userspace Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-16 18:15 ` Oliver Upton
2021-09-30 19:14 ` Marcelo Tosatti
2021-09-30 19:14 ` Marcelo Tosatti
2021-09-30 19:14 ` Marcelo Tosatti
2021-10-01 9:17 ` Paolo Bonzini [this message]
2021-10-01 9:17 ` Paolo Bonzini
2021-10-01 9:17 ` Paolo Bonzini
2021-10-01 10:32 ` Marcelo Tosatti
2021-10-01 10:32 ` Marcelo Tosatti
2021-10-01 10:32 ` Marcelo Tosatti
2021-10-01 15:12 ` Paolo Bonzini
2021-10-01 15:12 ` Paolo Bonzini
2021-10-01 15:12 ` Paolo Bonzini
2021-10-01 19:11 ` Marcelo Tosatti
2021-10-01 19:11 ` Marcelo Tosatti
2021-10-01 19:11 ` Marcelo Tosatti
2021-10-01 19:33 ` Oliver Upton
2021-10-01 19:33 ` Oliver Upton
2021-10-01 19:33 ` Oliver Upton
2021-10-04 14:30 ` Marcelo Tosatti
2021-10-04 14:30 ` Marcelo Tosatti
2021-10-04 14:30 ` Marcelo Tosatti
2021-10-04 11:44 ` Paolo Bonzini
2021-10-04 11:44 ` Paolo Bonzini
2021-10-04 11:44 ` Paolo Bonzini
2021-10-05 15:22 ` Sean Christopherson
2021-10-05 15:22 ` Sean Christopherson
2021-10-05 15:22 ` Sean Christopherson
2022-02-23 10:02 ` David Woodhouse
2022-02-23 10:02 ` David Woodhouse
2022-02-23 10:02 ` David Woodhouse
2021-09-24 16:43 ` [PATCH v8 0/7] KVM: x86: Add idempotent controls for migrating system counter state Paolo Bonzini
2021-09-24 16:43 ` Paolo Bonzini
2021-09-24 16:43 ` Paolo Bonzini
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