From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC PATCH 2/9] genirq: Allow the state of a forwarded irq to be save/restored
Date: Fri, 27 Jun 2014 14:10:18 +0100 [thread overview]
Message-ID: <20140627131018.GS26276@arm.com> (raw)
In-Reply-To: <1403688530-23273-3-git-send-email-marc.zyngier@arm.com>
Hi Marc,
On Wed, Jun 25, 2014 at 10:28:43AM +0100, Marc Zyngier wrote:
> When a peripheral is shared between virtual machines, its interrupt
> state becomes part of the guest's state, and must be switched accordingly.
>
> Introduce a pair of accessors (irq_get_fwd_state/irq_set_fwd_state) to
> retrieve the bits that can be of interest to KVM: pending, active, and masked.
>
> - irq_get_fwd_state returns the state of the interrupt according to a mask
> containing any of the IRQ_STATE_PENDING, IRQ_STATE_ACTIVE or IRQ_STATE_MASKED
> bits.
> - irq_set_fwd_state sets the state of the interrupt according to a similar mask.
>
> Only a forwarded interrupt can be manipulated in such a way.
[...]
> +/**
> + * irq_set_fwd_state - set the state of a forwarded interrupt.
> + * @irq: Interrupt line that is forwarded to a VM
> + * @val: State to be restored
> + * @mask: Bitmask of IRQ_FWD_STATE_* defining the valid bits in @val
> + *
> + * This call sets the state of a forwarded interrupt, depending
> + * on the mask which indicates the valid bits.
> + *
> + * This function should be called with preemption disabled if the
> + * interrupt controller has per-cpu registers.
> + */
> +int irq_set_fwd_state(unsigned int irq, u32 val, u32 mask)
> +{
> + struct irq_desc *desc;
> + struct irq_data *data;
> + struct irq_chip *chip;
> + unsigned long flags;
> +
> + desc = irq_to_desc(irq);
> + if (!desc)
> + return -EINVAL;
> +
> + data = irq_desc_get_irq_data(desc);
> + if (!irqd_irq_forwarded(data))
> + return -EINVAL;
> +
> + chip = irq_desc_get_chip(desc);
> + if (!chip->irq_set_fwd_state)
> + return -EINVAL;
> +
> + chip_bus_lock(desc);
> + raw_spin_lock_irqsave(&desc->lock, flags);
> + chip->irq_set_fwd_state(data, val, mask);
> + raw_spin_unlock_irqrestore(&desc->lock, flags);
> + chip_bus_sync_unlock(desc);
Having looked at this, I don't think you need to take the desc->lock after
all. I thought you might need it for irq_desc_get_chip, but that's not going
to change dynamically and you'd end up with a lock ordering problem against
chip_bus_lock anyway.
Will
next prev parent reply other threads:[~2014-06-27 13:10 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-25 9:28 [RFC PATCH 0/9] ARM: Forwarding physical interrupts to a guest VM Marc Zyngier
2014-06-25 9:28 ` [RFC PATCH 1/9] genirq: Add IRQD_IRQ_FORWARDED flag and accessors Marc Zyngier
2014-06-25 9:28 ` [RFC PATCH 2/9] genirq: Allow the state of a forwarded irq to be save/restored Marc Zyngier
2014-06-27 13:10 ` Will Deacon [this message]
2014-07-07 8:40 ` Marc Zyngier
2014-06-25 9:28 ` [RFC PATCH 3/9] irqchip: GIC: Convert to EOImode == 1 Marc Zyngier
2014-06-25 12:50 ` Rob Herring
2014-06-25 13:03 ` Marc Zyngier
2014-06-25 13:18 ` Rob Herring
2014-06-25 13:56 ` Anup Patel
2014-06-25 14:03 ` Ian Campbell
2014-06-25 14:31 ` Marc Zyngier
2014-06-25 14:08 ` Rob Herring
2014-06-25 14:24 ` Marc Zyngier
2014-06-25 14:27 ` Ian Campbell
2014-06-25 20:14 ` Joel Schopp
2014-06-30 19:09 ` Stefano Stabellini
2014-07-01 8:24 ` Marc Zyngier
2014-07-01 16:34 ` Stefano Stabellini
2014-07-01 16:42 ` Marc Zyngier
2014-06-25 14:06 ` Peter Maydell
2014-06-25 14:46 ` Marc Zyngier
2014-08-06 11:30 ` Christoffer Dall
2014-07-25 12:42 ` Eric Auger
2014-06-25 9:28 ` [RFC PATCH 4/9] irqchip: GIC: add support for forwarded interrupts Marc Zyngier
2014-06-27 13:17 ` Will Deacon
2014-07-07 10:43 ` Marc Zyngier
2014-08-06 11:30 ` Christoffer Dall
2014-06-25 9:28 ` [RFC PATCH 5/9] irqchip: GICv3: Convert to EOImode == 1 Marc Zyngier
2014-06-25 9:28 ` [RFC PATCH 6/9] irqchip: GICv3: add support for forwarded interrupts Marc Zyngier
2014-06-25 9:28 ` [RFC PATCH 7/9] KVM: arm: vgic: allow dynamic mapping of physical/virtual interrupts Marc Zyngier
2014-08-03 9:48 ` Eric Auger
2014-08-04 13:13 ` Marc Zyngier
2014-08-07 15:47 ` Eric Auger
2014-08-11 8:01 ` Christoffer Dall
2014-08-11 13:22 ` Eric Auger
2014-06-25 9:28 ` [RFC PATCH 8/9] arm: KVM: timer: move the timer switch into the non-preemptible section Marc Zyngier
2014-06-25 9:28 ` [RFC PATCH 9/9] KVM: arm: timer: make the interrupt state part of the timer state Marc Zyngier
2014-06-25 14:52 ` [RFC PATCH 0/9] ARM: Forwarding physical interrupts to a guest VM Eric Auger
2014-06-26 9:31 ` Marc Zyngier
2014-06-26 12:58 ` Eric Auger
2014-06-26 14:12 ` Marc Zyngier
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