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From: Catalin Marinas <catalin.marinas@arm.com>
To: Christoffer Dall <cdall@linaro.org>
Cc: kvm@vger.kernel.org, Marc Zyngier <marc.zyngier@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v5 03/20] arm64: Use physical counter for in-kernel reads when booted in EL2
Date: Fri, 27 Oct 2017 11:53:42 +0100	[thread overview]
Message-ID: <20171027105341.rpomiwsospi76o4k@armageddon.cambridge.arm.com> (raw)
In-Reply-To: <1509093281-15225-4-git-send-email-cdall@linaro.org>

On Fri, Oct 27, 2017 at 10:34:24AM +0200, Christoffer Dall wrote:
> Using the physical counter allows KVM to retain the offset between the
> virtual and physical counter as long as it is actively running a VCPU.
> 
> As soon as a VCPU is released, another thread is scheduled or we start
> running userspace applications, we reset the offset to 0, so that
> userspace accessing the virtual timer can still read the virtual counter
> and get the same view of time as the kernel.
> 
> This opens up potential improvements for KVM performance, but we have to
> make a few adjustments to preserve system consistency.
> 
> Currently get_cycles() is hardwired to arch_counter_get_cntvct() on
> arm64, but as we move to using the physical timer for the in-kernel
> time-keeping on systems that boot in EL2, we should use the same counter
> for get_cycles() as for other in-kernel timekeeping operations.
> 
> Similarly, implementations of arch_timer_set_next_event_phys() is
> modified to use the counter specific to the timer being programmed.
> 
> VHE kernels or kernels continuing to use the virtual timer are
> unaffected.
> 
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Christoffer Dall <cdall@linaro.org>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

WARNING: multiple messages have this Message-ID (diff)
From: catalin.marinas@arm.com (Catalin Marinas)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v5 03/20] arm64: Use physical counter for in-kernel reads when booted in EL2
Date: Fri, 27 Oct 2017 11:53:42 +0100	[thread overview]
Message-ID: <20171027105341.rpomiwsospi76o4k@armageddon.cambridge.arm.com> (raw)
In-Reply-To: <1509093281-15225-4-git-send-email-cdall@linaro.org>

On Fri, Oct 27, 2017 at 10:34:24AM +0200, Christoffer Dall wrote:
> Using the physical counter allows KVM to retain the offset between the
> virtual and physical counter as long as it is actively running a VCPU.
> 
> As soon as a VCPU is released, another thread is scheduled or we start
> running userspace applications, we reset the offset to 0, so that
> userspace accessing the virtual timer can still read the virtual counter
> and get the same view of time as the kernel.
> 
> This opens up potential improvements for KVM performance, but we have to
> make a few adjustments to preserve system consistency.
> 
> Currently get_cycles() is hardwired to arch_counter_get_cntvct() on
> arm64, but as we move to using the physical timer for the in-kernel
> time-keeping on systems that boot in EL2, we should use the same counter
> for get_cycles() as for other in-kernel timekeeping operations.
> 
> Similarly, implementations of arch_timer_set_next_event_phys() is
> modified to use the counter specific to the timer being programmed.
> 
> VHE kernels or kernels continuing to use the virtual timer are
> unaffected.
> 
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Christoffer Dall <cdall@linaro.org>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

  reply	other threads:[~2017-10-27 10:53 UTC|newest]

Thread overview: 64+ 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 ` 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   ` 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  8:34   ` Christoffer Dall
2017-10-27 10:53   ` Catalin Marinas
2017-10-27 10:53     ` Catalin Marinas
2017-10-29  1:51     ` Christoffer Dall
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  8:34   ` Christoffer Dall
2017-10-27 10:53   ` Catalin Marinas [this message]
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
2017-10-27  8:34   ` Christoffer Dall
2017-11-16 12:29   ` Andre Przywara
2017-11-16 12:29     ` Andre Przywara
2017-11-20 11:20     ` Christoffer Dall
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   ` 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   ` 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   ` 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   ` 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   ` 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   ` 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   ` 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   ` Christoffer Dall
2017-10-27  8:34   ` Christoffer Dall
2017-10-29 15:22   ` [tip:irq/core] " tip-bot for 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   ` 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   ` 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   ` 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   ` 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   ` 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   ` Christoffer Dall
2017-10-27  8:34 ` [PATCH v5 19/20] KVM: arm/arm64: Get rid of kvm_timer_flush_hwstate Christoffer Dall
2017-10-27  8:34   ` Christoffer Dall
2017-11-27 16:50   ` Andrew Jones
2017-11-27 16:50     ` Andrew Jones
2017-11-29 17:39     ` Christoffer Dall
2017-11-29 17:39       ` Christoffer Dall
2017-11-29 18:17       ` Andrew Jones
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
2017-10-27  8:34   ` 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  1:48   ` Christoffer Dall
2017-10-29  2:07   ` Marc Zyngier
2017-10-29  2:07     ` Marc Zyngier

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