From: Marc Zyngier <maz@kernel.org>
To: "Veith, Simon" <sveith@amazon.de>
Cc: "kvmarm@lists.linux.dev" <kvmarm@lists.linux.dev>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"dwmw2@infradead.org" <dwmw2@infradead.org>,
"yuzenghui@huawei.com" <yuzenghui@huawei.com>,
"suzuki.poulose@arm.com" <suzuki.poulose@arm.com>,
"james.morse@arm.com" <james.morse@arm.com>,
"oliver.upton@linux.dev" <oliver.upton@linux.dev>,
"ricarkol@google.com" <ricarkol@google.com>
Subject: Re: [PATCH 00/16] KVM: arm64: Rework timer offsetting for fun and profit
Date: Tue, 21 Feb 2023 22:17:54 +0000 [thread overview]
Message-ID: <87lekqzmr1.wl-maz@kernel.org> (raw)
In-Reply-To: <5404a3554c3a1efd1e8e098072a4cf03d1b01152.camel@amazon.de>
Hi Simon,
On Tue, 21 Feb 2023 16:28:36 +0000,
"Veith, Simon" <sveith@amazon.de> wrote:
>
> Hello Marc,
>
> On Thu, 2023-02-16 at 14:21 +0000, Marc Zyngier wrote:
> > This series aims at satisfying multiple goals:
> >
> > - allow a VMM to atomically restore a timer offset for a whole VM
> > instead of updating the offset each time a vcpu get its counter
> > written
> >
> > - allow a VMM to save/restore the physical timer context, something
> > that we cannot do at the moment due to the lack of offsetting
> >
> > - provide a framework that is suitable for NV support, where we get
> > both global and per timer, per vcpu offsetting
>
> Thank you so much for following up on my (admittedly very basic) patch
> with your own proposal!
No worries. There is nothing like "nerd sniping"... ;-)
> > This has been moderately tested with nVHE, VHE and NV. I do not have
> > access to CNTPOFF-aware HW, so the jury is still out on that one
>
> Same here about CNTPOFF -- I gave it a quick spin on Graviton2 and
> Graviton3, and neither chip claims the ARM64_HAS_ECV_CNTPOFF capability
> from your patch.
Nah, G2/G3 are old stuff (v8.2 and v8.3+ respectively). You need at
least a v8.6 system, something that is made of the best Unobtainium
money can buy. M2 has ECV, but without CNTPOFF, which is just silly.
> I am working on testing your series with our userspace and will report
> back.
Thanks a lot, that'd be super helpful. Please don't get too attached
to the userspace interface though, as it is likely to change (Oliver
has an interesting suggestion to simplify it, but I need to convince
myself that it doesn't break migration of the physical timer).
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2023-02-21 22:19 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-16 14:21 [PATCH 00/16] KVM: arm64: Rework timer offsetting for fun and profit Marc Zyngier
2023-02-16 14:21 ` [PATCH 01/16] arm64: Add CNTPOFF_EL2 register definition Marc Zyngier
2023-02-16 14:21 ` [PATCH 02/16] arm64: Add HAS_ECV_CNTPOFF capability Marc Zyngier
2023-02-22 4:30 ` Reiji Watanabe
2023-02-22 10:47 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 03/16] kvm: arm64: Expose {un,}lock_all_vcpus() to the reset of KVM Marc Zyngier
2023-02-23 22:30 ` Colton Lewis
2023-02-16 14:21 ` [PATCH 04/16] KVM: arm64: timers: Use a per-vcpu, per-timer accumulator for fractional ns Marc Zyngier
2023-02-23 22:30 ` Colton Lewis
2023-02-16 14:21 ` [PATCH 05/16] KVM: arm64: timers: Convert per-vcpu virtual offset to a global value Marc Zyngier
2023-02-22 6:15 ` Reiji Watanabe
2023-02-22 10:54 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 06/16] KVM: arm64: timers: Use CNTPOFF_EL2 to offset the physical timer Marc Zyngier
2023-02-23 22:34 ` Colton Lewis
2023-02-24 8:59 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 07/16] KVM: arm64: timers: Allow physical offset without CNTPOFF_EL2 Marc Zyngier
2023-02-23 22:40 ` Colton Lewis
2023-02-24 10:54 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 08/16] KVM: arm64: timers: Allow userspace to set the counter offsets Marc Zyngier
2023-02-16 22:09 ` Oliver Upton
2023-02-17 10:17 ` Marc Zyngier
2023-02-17 22:11 ` Oliver Upton
2023-02-22 11:56 ` Marc Zyngier
2023-02-22 16:34 ` Oliver Upton
2023-02-23 18:25 ` Marc Zyngier
2023-03-08 7:46 ` Oliver Upton
2023-03-08 7:53 ` Oliver Upton
2023-03-09 8:29 ` Marc Zyngier
2023-03-09 8:25 ` Marc Zyngier
2023-02-23 22:41 ` Colton Lewis
2023-02-24 11:24 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 09/16] KVM: arm64: timers: Allow save/restoring of the physical timer Marc Zyngier
2023-02-16 14:21 ` [PATCH 10/16] KVM: arm64: timers: Rationalise per-vcpu timer init Marc Zyngier
2023-02-16 14:21 ` [PATCH 11/16] KVM: arm64: Document KVM_ARM_SET_CNT_OFFSETS and co Marc Zyngier
2023-02-16 14:21 ` [PATCH 12/16] KVM: arm64: nv: timers: Add a per-timer, per-vcpu offset Marc Zyngier
2023-02-24 20:07 ` Colton Lewis
2023-02-25 10:32 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 13/16] KVM: arm64: nv: timers: Support hyp timer emulation Marc Zyngier
2023-02-24 20:08 ` Colton Lewis
2023-02-25 10:34 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 14/16] KVM: arm64: selftests: Add physical timer registers to the sysreg list Marc Zyngier
2023-02-16 14:21 ` [PATCH 15/16] KVM: arm64: selftests: Augment existing timer test to handle variable offsets Marc Zyngier
2023-03-06 22:08 ` Colton Lewis
2023-03-09 9:01 ` Marc Zyngier
2023-03-10 19:26 ` Colton Lewis
2023-03-12 15:53 ` Marc Zyngier
2023-03-13 11:43 ` Marc Zyngier
2023-03-14 17:47 ` Colton Lewis
2023-03-14 18:18 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 16/16] KVM: arm64: selftests: Deal with spurious timer interrupts Marc Zyngier
2023-02-21 16:28 ` [PATCH 00/16] KVM: arm64: Rework timer offsetting for fun and profit Veith, Simon
2023-02-21 22:17 ` Marc Zyngier [this message]
2023-02-23 22:29 ` Colton Lewis
2023-02-24 8:45 ` Marc Zyngier
2023-02-24 20:07 ` Colton Lewis
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