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From: Christoffer Dall <christoffer.dall@arm.com>
To: Julien Thierry <julien.thierry@arm.com>
Cc: linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
	marc.zyngier@arm.com, linux-arm-kernel@lists.infradead.org,
	linux-rt-users@vger.kernel.org, tglx@linutronix.de,
	rostedt@goodmis.org, bigeasy@linutronix.de
Subject: Re: [PATCH 0/4] KVM: arm/arm64: vgic: Use raw_spinlock for locks taken in IRQ context
Date: Tue, 20 Nov 2018 15:20:00 +0100	[thread overview]
Message-ID: <20181120142000.GB11162@e113682-lin.lund.arm.com> (raw)
In-Reply-To: <1542647279-46609-1-git-send-email-julien.thierry@arm.com>

On Mon, Nov 19, 2018 at 05:07:55PM +0000, Julien Thierry wrote:
> While testing KVM running on PREEMPT_RT, starting guest could simply
> freeze the machine. This is because we are using spinlocks for VGIC
> locks, which is invalid in the VGIC case since the locks must be take
> with interrupts disabled.
> 
> The solution is to use raw_spinlock instead of spinlocks.
> 
> Replacing those locks also highlighted an issue where we attempt to
> cond_resched with interrupts disabled.
> 
> Patch 1 fixes the cond_resched issue.

I don't agree with this fix without seeing a more thorough analysis.

> Patch 2-4 replace the VGIC spinlocks with raw_spinlocks
> 

For these:

Acked-by: Christoffer Dall <christoffer.dall@arm.com>



Thanks,

    Christoffer

      parent reply	other threads:[~2018-11-20 14:20 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-19 17:07 [PATCH 0/4] KVM: arm/arm64: vgic: Use raw_spinlock for locks taken in IRQ context Julien Thierry
2018-11-19 17:07 ` [PATCH 1/4] KVM: arm/arm64: vgic: Do not cond_resched_lock() with IRQs disabled Julien Thierry
2018-11-20 14:18   ` Christoffer Dall
2018-11-20 14:37     ` Marc Zyngier
2018-11-20 17:22     ` Julien Thierry
2018-11-19 17:07 ` [PATCH 2/4] KVM: arm/arm64: vgic: Make vgic_irq->irq_lock a raw_spinlock Julien Thierry
2018-11-19 17:07 ` [PATCH 3/4] KVM: arm/arm64: vgic: Make vgic_dist->lpi_list_lock " Julien Thierry
2018-11-19 17:07 ` [PATCH 4/4] KVM: arm/arm64: vgic: Make vgic_cpu->ap_list_lock " Julien Thierry
2018-11-20 14:20 ` Christoffer Dall [this message]

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