From: Marc Zyngier <maz@kernel.org>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: kvmarm@lists.linux.dev, kvm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Ricardo Koller <ricarkol@google.com>,
Simon Veith <sveith@amazon.de>,
Reiji Watanabe <reijiw@google.com>,
Colton Lewis <coltonlewis@google.com>,
Joey Gouly <joey.gouly@arm.com>,
dwmw2@infradead.org
Subject: Re: [PATCH v3 05/18] KVM: arm64: timers: Allow physical offset without CNTPOFF_EL2
Date: Thu, 30 Mar 2023 11:09:35 +0100 [thread overview]
Message-ID: <86h6u2wnxc.wl-maz@kernel.org> (raw)
In-Reply-To: <ZCUvZ9yhfRSKRb3n@linux.dev>
On Thu, 30 Mar 2023 07:42:47 +0100,
Oliver Upton <oliver.upton@linux.dev> wrote:
>
> Hey Marc,
>
> On Fri, Mar 24, 2023 at 02:46:51PM +0000, Marc Zyngier wrote:
> > CNTPOFF_EL2 is awesome, but it is mostly vapourware, and no publicly
> > available implementation has it. So for the common mortals, let's
> > implement the emulated version of this thing.
> >
> > It means trapping accesses to the physical counter and timer, and
> > emulate some of it as necessary.
> >
> > As for CNTPOFF_EL2, nobody sets the offset yet.
>
> Did you consider implementing a 'fast' exit handler for counter reads?
> When I took a stab at this a long time ago I had something similar [*].
> Since physical counter emulation is going to effectively be used by all
> systems out there right now it might be worth giving the best emulation
> implementation we can.
Indeed, I have some of that in the NV code, which needs to be
augmented. I'm not sure any guest deeply cares about the physical
counter outside of NV, but I'm happy to hack something together if
someone screams loudly enough!
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
_______________________________________________
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:[~2023-03-30 10:10 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-24 14:46 [PATCH v3 00/18] KVM: arm64: Rework timer offsetting for fun and profit Marc Zyngier
2023-03-24 14:46 ` [PATCH v3 01/18] KVM: arm64: timers: Use a per-vcpu, per-timer accumulator for fractional ns Marc Zyngier
2023-03-24 14:46 ` [PATCH v3 02/18] arm64: Add CNTPOFF_EL2 register definition Marc Zyngier
2023-03-24 14:46 ` [PATCH v3 03/18] arm64: Add HAS_ECV_CNTPOFF capability Marc Zyngier
2023-03-24 14:46 ` [PATCH v3 04/18] KVM: arm64: timers: Use CNTPOFF_EL2 to offset the physical timer Marc Zyngier
2023-03-24 14:46 ` [PATCH v3 05/18] KVM: arm64: timers: Allow physical offset without CNTPOFF_EL2 Marc Zyngier
2023-03-30 6:42 ` Oliver Upton
2023-03-30 10:09 ` Marc Zyngier [this message]
2023-03-24 14:46 ` [PATCH v3 06/18] KVM: arm64: Expose {un,}lock_all_vcpus() to the rest of KVM Marc Zyngier
2023-03-24 14:46 ` [PATCH v3 07/18] KVM: arm64: timers: Allow userspace to set the global counter offset Marc Zyngier
2023-03-30 6:26 ` Oliver Upton
2023-03-30 10:15 ` Marc Zyngier
2023-03-24 14:46 ` [PATCH v3 08/18] KVM: arm64: timers: Allow save/restoring of the physical timer Marc Zyngier
2023-03-24 14:46 ` [PATCH v3 09/18] KVM: arm64: timers: Rationalise per-vcpu timer init Marc Zyngier
2023-03-24 14:46 ` [PATCH v3 10/18] KVM: arm64: timers: Abstract per-timer IRQ access Marc Zyngier
2023-03-24 14:46 ` [PATCH v3 11/18] KVM: arm64: timers: Move the timer IRQs into arch_timer_vm_data Marc Zyngier
2023-03-30 7:02 ` Oliver Upton
2023-03-30 10:19 ` Marc Zyngier
2023-03-24 14:46 ` [PATCH v3 12/18] KVM: arm64: Abstract the number of valid timers per vcpu Marc Zyngier
2023-03-24 14:46 ` [PATCH v3 13/18] KVM: arm64: Document KVM_ARM_SET_CNT_OFFSETS and co Marc Zyngier
2023-03-24 14:47 ` [PATCH v3 14/18] KVM: arm64: nv: timers: Add a per-timer, per-vcpu offset Marc Zyngier
2023-03-24 14:47 ` [PATCH v3 15/18] KVM: arm64: nv: timers: Support hyp timer emulation Marc Zyngier
2023-03-24 14:47 ` [PATCH v3 16/18] KVM: arm64: selftests: Add physical timer registers to the sysreg list Marc Zyngier
2023-03-24 14:47 ` [PATCH v3 17/18] KVM: arm64: selftests: Deal with spurious timer interrupts Marc Zyngier
2023-03-24 14:47 ` [PATCH v3 18/18] KVM: arm64: selftests: Augment existing timer test to handle variable offset Marc Zyngier
2023-03-29 5:41 ` [PATCH v3 00/18] KVM: arm64: Rework timer offsetting for fun and profit Veith, Simon
2023-03-30 17:46 ` Marc Zyngier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=86h6u2wnxc.wl-maz@kernel.org \
--to=maz@kernel.org \
--cc=coltonlewis@google.com \
--cc=dwmw2@infradead.org \
--cc=james.morse@arm.com \
--cc=joey.gouly@arm.com \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.linux.dev \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=oliver.upton@linux.dev \
--cc=reijiw@google.com \
--cc=ricarkol@google.com \
--cc=suzuki.poulose@arm.com \
--cc=sveith@amazon.de \
--cc=yuzenghui@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).