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From: Joerg Roedel <joro@8bytes.org>
To: Julien Grall <julien.grall@arm.com>
Cc: jason@lakedaemon.net, douliyangs@gmail.com, marc.zyngier@arm.com,
	robin.murphy@arm.com, bigeasy@linutronix.de,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	miquel.raynal@bootlin.com, tglx@linutronix.de,
	logang@deltatee.com, linux-rt-users@vger.kernel.org
Subject: Re: [PATCH v3 2/7] iommu/dma-iommu: Split iommu_dma_map_msi_msg() in two parts
Date: Fri, 3 May 2019 16:03:55 +0200	[thread overview]
Message-ID: <20190503140355.GC6731@8bytes.org> (raw)
In-Reply-To: <20190501135824.25586-3-julien.grall@arm.com>

On Wed, May 01, 2019 at 02:58:19PM +0100, Julien Grall wrote:
> On RT, iommu_dma_map_msi_msg() may be called from non-preemptible
> context. This will lead to a splat with CONFIG_DEBUG_ATOMIC_SLEEP as
> the function is using spin_lock (they can sleep on RT).
> 
> iommu_dma_map_msi_msg() is used to map the MSI page in the IOMMU PT
> and update the MSI message with the IOVA.
> 
> Only the part to lookup for the MSI page requires to be called in
> preemptible context. As the MSI page cannot change over the lifecycle
> of the MSI interrupt, the lookup can be cached and re-used later on.
> 
> iomma_dma_map_msi_msg() is now split in two functions:
>     - iommu_dma_prepare_msi(): This function will prepare the mapping
>     in the IOMMU and store the cookie in the structure msi_desc. This
>     function should be called in preemptible context.
>     - iommu_dma_compose_msi_msg(): This function will update the MSI
>     message with the IOVA when the device is behind an IOMMU.
> 
> Signed-off-by: Julien Grall <julien.grall@arm.com>
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> Reviewed-by: Eric Auguer <eric.auger@redhat.com>

Acked-by: Joerg Roedel <jroedel@suse.de>
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro@8bytes.org>
To: Julien Grall <julien.grall@arm.com>
Cc: linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	logang@deltatee.com, douliyangs@gmail.com,
	miquel.raynal@bootlin.com, marc.zyngier@arm.com,
	jason@lakedaemon.net, tglx@linutronix.de, robin.murphy@arm.com,
	bigeasy@linutronix.de, linux-rt-users@vger.kernel.org,
	Eric Auguer <eric.auger@redhat.com>
Subject: Re: [PATCH v3 2/7] iommu/dma-iommu: Split iommu_dma_map_msi_msg() in two parts
Date: Fri, 3 May 2019 16:03:55 +0200	[thread overview]
Message-ID: <20190503140355.GC6731@8bytes.org> (raw)
In-Reply-To: <20190501135824.25586-3-julien.grall@arm.com>

On Wed, May 01, 2019 at 02:58:19PM +0100, Julien Grall wrote:
> On RT, iommu_dma_map_msi_msg() may be called from non-preemptible
> context. This will lead to a splat with CONFIG_DEBUG_ATOMIC_SLEEP as
> the function is using spin_lock (they can sleep on RT).
> 
> iommu_dma_map_msi_msg() is used to map the MSI page in the IOMMU PT
> and update the MSI message with the IOVA.
> 
> Only the part to lookup for the MSI page requires to be called in
> preemptible context. As the MSI page cannot change over the lifecycle
> of the MSI interrupt, the lookup can be cached and re-used later on.
> 
> iomma_dma_map_msi_msg() is now split in two functions:
>     - iommu_dma_prepare_msi(): This function will prepare the mapping
>     in the IOMMU and store the cookie in the structure msi_desc. This
>     function should be called in preemptible context.
>     - iommu_dma_compose_msi_msg(): This function will update the MSI
>     message with the IOVA when the device is behind an IOMMU.
> 
> Signed-off-by: Julien Grall <julien.grall@arm.com>
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> Reviewed-by: Eric Auguer <eric.auger@redhat.com>

Acked-by: Joerg Roedel <jroedel@suse.de>

  reply	other threads:[~2019-05-03 14:04 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-01 13:58 [PATCH v3 0/7] iommu/dma-iommu: Split iommu_dma_map_msi_msg in two parts Julien Grall
2019-05-01 13:58 ` Julien Grall
2019-05-01 13:58 ` [PATCH v3 1/7] genirq/msi: Add a new field in msi_desc to store an IOMMU cookie Julien Grall
2019-05-01 13:58   ` Julien Grall
2019-05-01 13:58 ` [PATCH v3 2/7] iommu/dma-iommu: Split iommu_dma_map_msi_msg() in two parts Julien Grall
2019-05-01 13:58   ` Julien Grall
2019-05-03 14:03   ` Joerg Roedel [this message]
2019-05-03 14:03     ` Joerg Roedel
2019-05-01 13:58 ` [PATCH v3 3/7] irqchip/gicv2m: Don't map the MSI page in gicv2m_compose_msi_msg() Julien Grall
2019-05-01 13:58   ` Julien Grall
2019-05-01 13:58 ` [PATCH v3 4/7] irqchip/gic-v3-its: Don't map the MSI page in its_irq_compose_msi_msg() Julien Grall
2019-05-01 13:58   ` Julien Grall
2019-05-01 13:58 ` [PATCH v3 5/7] irqchip/ls-scfg-msi: Don't map the MSI page in ls_scfg_msi_compose_msg() Julien Grall
2019-05-01 13:58   ` Julien Grall
2019-05-01 13:58 ` [PATCH v3 6/7] irqchip/gic-v3-mbi: Don't map the MSI page in mbi_compose_m{b, s}i_msg() Julien Grall
2019-05-01 13:58   ` Julien Grall
2019-05-03 14:27   ` Marc Zyngier
2019-05-03 14:27     ` Marc Zyngier
2019-05-03 14:52     ` Robin Murphy
2019-05-03 14:52       ` Robin Murphy
2019-05-01 13:58 ` [PATCH v3 7/7] iommu/dma-iommu: Remove iommu_dma_map_msi_msg() Julien Grall
2019-05-01 13:58   ` Julien Grall
2019-05-03 14:04   ` Joerg Roedel
2019-05-03 14:04     ` Joerg Roedel

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