From: Christoffer Dall <christoffer.dall@linaro.org> To: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Cc: Marc Zyngier <marc.zyngier@arm.com>, Eric Auger <eric.auger@redhat.com>, kvm@vger.kernel.org, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Christoffer Dall <christoffer.dall@linaro.org> Subject: [PATCH v5 21/20] arm/arm64: KVM: Load the timer state when enabling the timer Date: Sun, 29 Oct 2017 02:48:56 +0100 [thread overview] Message-ID: <1509241736-99913-1-git-send-email-christoffer.dall@linaro.org> (raw) In-Reply-To: <1509093281-15225-1-git-send-email-cdall@linaro.org> 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> --- virt/kvm/arm/arch_timer.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index 2035cf2..4db54ff 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -861,7 +861,11 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu) return ret; no_vgic: + preempt_disable(); timer->enabled = 1; + kvm_timer_vcpu_load_vgic(vcpu); + preempt_enable(); + return 0; } -- 2.7.4
WARNING: multiple messages have this Message-ID (diff)
From: christoffer.dall@linaro.org (Christoffer Dall) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v5 21/20] arm/arm64: KVM: Load the timer state when enabling the timer Date: Sun, 29 Oct 2017 02:48:56 +0100 [thread overview] Message-ID: <1509241736-99913-1-git-send-email-christoffer.dall@linaro.org> (raw) In-Reply-To: <1509093281-15225-1-git-send-email-cdall@linaro.org> 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> --- virt/kvm/arm/arch_timer.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index 2035cf2..4db54ff 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -861,7 +861,11 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu) return ret; no_vgic: + preempt_disable(); timer->enabled = 1; + kvm_timer_vcpu_load_vgic(vcpu); + preempt_enable(); + return 0; } -- 2.7.4
next prev parent reply other threads:[~2017-10-29 1:49 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 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 ` Christoffer Dall [this message] 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 2017-10-29 2:07 ` Marc Zyngier
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