From: Marc Zyngier <marc.zyngier@arm.com>
To: Christoffer Dall <christoffer.dall@linaro.org>
Cc: kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
Eric Auger <eric.auger@redhat.com>,
kvm@vger.kernel.org, Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH v5 21/20] arm/arm64: KVM: Load the timer state when enabling the timer
Date: Sun, 29 Oct 2017 02:07:38 +0000 [thread overview]
Message-ID: <86she2905x.fsf@arm.com> (raw)
In-Reply-To: <1509241736-99913-1-git-send-email-christoffer.dall@linaro.org> (Christoffer Dall's message of "Sun, 29 Oct 2017 02:48:56 +0100")
On Sun, Oct 29 2017 at 2:48:56 am GMT, Christoffer Dall <christoffer.dall@linaro.org> wrote:
> After being lazy with saving/restoring the timer state, we defer that
> work to vcpu_load and vcpu_put, which ensure that the timer state is
> loaded on the hardware timers whenever the VCPU runs.
>
> Unfortunately, we are failing to do that the first time vcpu_load()
> runs, because the timer has not yet been enabled at that time. As long
> as the initialized timer state matches what happens to be in the
> hardware (a disabled timer, because we never leave the timer screaming),
> this does not show up as a problem, but is nevertheless incorrect.
>
> The solution is simple; disable preemption while setting the timer to be
> enabled, and call the timer load function when first enabling the timer.
>
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
M.
--
Jazz is not dead. It just smells funny.
prev parent reply other threads:[~2017-10-29 2:07 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-27 8:34 [PATCH v5 00/20] KVM: arm/arm64: Optimize arch timer register handling Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 01/20] irqchip/gic: Deal with broken firmware exposing only 4kB of GICv2 CPU interface Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 02/20] arm64: Implement arch_counter_get_cntpct to read the physical counter Christoffer Dall
2017-10-27 10:53 ` Catalin Marinas
2017-10-29 1:51 ` Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 03/20] arm64: Use physical counter for in-kernel reads when booted in EL2 Christoffer Dall
2017-10-27 10:53 ` Catalin Marinas
2017-10-27 8:34 ` [PATCH v5 04/20] KVM: arm/arm64: Guard kvm_vgic_map_is_active against !vgic_initialized Christoffer Dall
2017-11-16 12:29 ` Andre Przywara
2017-11-20 11:20 ` Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 05/20] KVM: arm/arm64: Support calling vgic_update_irq_pending from irq context Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 06/20] KVM: arm/arm64: Check that system supports split eoi/deactivate Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 07/20] KVM: arm/arm64: Make timer_arm and timer_disarm helpers more generic Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 08/20] KVM: arm/arm64: Rename soft timer to bg_timer Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 09/20] KVM: arm/arm64: Move timer/vgic flush/sync under disabled irq Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 10/20] KVM: arm/arm64: Use separate timer for phys timer emulation Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 11/20] KVM: arm/arm64: Move timer save/restore out of the hyp code Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 12/20] genirq: Document vcpu_info usage for percpu_devid interrupts Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 13/20] KVM: arm/arm64: Set VCPU affinity for virt timer irq Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 14/20] KVM: arm/arm64: Avoid timer save/restore in vcpu entry/exit Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 15/20] KVM: arm/arm64: Support EL1 phys timer register access in set/get reg Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 16/20] KVM: arm/arm64: Use kvm_arm_timer_set/get_reg for guest register traps Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 17/20] KVM: arm/arm64: Move phys_timer_emulate function Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 18/20] KVM: arm/arm64: Avoid phys timer emulation in vcpu entry/exit Christoffer Dall
2017-10-27 8:34 ` [PATCH v5 19/20] KVM: arm/arm64: Get rid of kvm_timer_flush_hwstate Christoffer Dall
2017-11-27 16:50 ` Andrew Jones
2017-11-29 17:39 ` Christoffer Dall
2017-11-29 18:17 ` Andrew Jones
2017-10-27 8:34 ` [PATCH v5 20/20] KVM: arm/arm64: Rework kvm_timer_should_fire Christoffer Dall
2017-10-29 1:48 ` [PATCH v5 21/20] arm/arm64: KVM: Load the timer state when enabling the timer Christoffer Dall
2017-10-29 2:07 ` Marc Zyngier [this message]
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