linux-kernel - Re: [PATCH v4 0/3] genirq: Saving/restoring the irqchip state of an irq line

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Date:	Mon, 13 Apr 2015 16:12:54 +0200
From:	Eric Auger <eric.auger@...aro.org>
To:	Marc Zyngier <marc.zyngier@....com>,
	Abhijeet Dharmapurikar <adharmap@...eaurora.org>,
	Stephen Boyd <sboyd@...eaurora.org>, Phong Vo <pvo@....com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Tin Huynh <tnhuynh@....com>, Y Vo <yvo@....com>,
	Thomas Gleixner <tglx@...utronix.de>, Toan Le <toanle@....com>,
	Bjorn Andersson <bjorn@...o.se>,
	Jason Cooper <jason@...edaemon.net>,
	Arnd Bergmann <arnd@...db.de>
CC:	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 0/3] genirq: Saving/restoring the irqchip state of
 an irq line

Hi Marc,

You can apply my R-b and T-b on the whole series. To be precise, I
tested the get path only with my kvm-vfio forward series.

Best Regards

Eric

Reviewed-by: Eric Auger <eric.auger@...aro.org>
Tested-by: Eric Auger <eric.auger@...aro.org>


On 03/18/2015 12:01 PM, Marc Zyngier wrote:
> Despite Linux offering a rather fine grained control over the life
> cycle of an interrupt, there is a few cases where it would be very
> useful to snapshot (or even set) the internal state of the interrupt
> controller for a given interrupt line:
> 
> - With KVM, a device shared between VMs must have its whole context
>   switched, and that includes the interrupt line state. KVM/arm is
>   moving to using this.
> - Some GPIO controllers seem to require peeking into the interrupt
>   controller they are connected to to report their internal state.
> 
> Instead of letting people facing this situation doing horrible
> (controller specific) hacks in their code, let's offer a couple of new
> entry points that allow a few attributes to be read and set.
> 
> Of course, this is a very dangerous thing to do if you don't know what
> you doing, and I wouldn't expect most drivers to use this. But this
> can also be a life saver at times.
> 
> This patch series implement said API, and adds support for this to the
> two main ARM interrupt controllers (GIC and GICv3). Available at:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git irq/irqchip_state
> 
> This has been fairly heavily tested with KVM on ARM, which makes use
> of this feature to context switch the timer interrupt (see the last
> three patch in the above branch).
> 
> Thanks,
> 
> 	M.
> 
> * From v3 [3]
> - Rebased on top of 4.0-rc4
> 
> * From v2 [2]:
> - Rebased on top of 3.19-rc3
> - Fixed irq_set_irqchip_state return value
> 
> * From v1 [1]:
> - Rebased on top of 3.18-rc7 + tip/irq/irqdomain-arm
> - Now deals with stacked domains
> - Changed the API to be less ambiguous (after review by tglx)
> - Added IRQCHIP_STATE_LINE_LEVEL (as requested by Bjorn Anderson)
> 
> [1] https://lkml.org/lkml/2014/10/25/134
> [2] https://lkml.org/lkml/2014/12/3/612
> [3] http://lkml.iu.edu/hypermail/linux/kernel/1501.0/03473.html
> 
> Marc Zyngier (3):
>   genirq: Allow the irqchip state of an IRQ to be save/restored
>   irqchip: GIC: Add support for irq_{get,set}_irqchip_state
>   irqchip: GICv3: Add support for irq_{get,set}_irqchip_state
> 
>  drivers/irqchip/irq-gic-v3.c | 83 +++++++++++++++++++++++++++++++++-------
>  drivers/irqchip/irq-gic.c    | 69 +++++++++++++++++++++++++++++++--
>  include/linux/interrupt.h    | 14 +++++++
>  include/linux/irq.h          |  6 +++
>  kernel/irq/manage.c          | 91 ++++++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 246 insertions(+), 17 deletions(-)
> 

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