linux-kernel - [PATCH 5/7] irqchip/ls-scfg-msi: Don't map the MSI page in ls_scfg_msi_compose

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Message-Id: <20190418172611.21561-6-julien.grall@arm.com>
Date:   Thu, 18 Apr 2019 18:26:09 +0100
From:   Julien Grall <julien.grall@....com>
To:     linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org
Cc:     logang@...tatee.com, douliyangs@...il.com,
        miquel.raynal@...tlin.com, marc.zyngier@....com,
        jason@...edaemon.net, tglx@...utronix.de, joro@...tes.org,
        robin.murphy@....com, bigeasy@...utronix.de,
        linux-rt-users@...r.kernel.org, Julien Grall <julien.grall@....com>
Subject: [PATCH 5/7] irqchip/ls-scfg-msi: Don't map the MSI page in ls_scfg_msi_compose_msg

The function ls_scfg_msi_compose_msg may be called from non-preemptible
context. However, on RT, iommu_dma_map_msi_msg requires to be called
from a preemptible context.

A recent patch split the function iommu_dma_map_msi_msg in 2 functions:
one that should be called in preemptible context, the other does
not have any requirement.

This patch reworks the FreeScale SCFG MSI driver to avoid executing
preemptible code in non-preemptible context by preparing the MSI mapping
when allocating the MSI interrupt.

Signed-off-by: Julien Grall <julien.grall@....com>
---
 drivers/irqchip/irq-ls-scfg-msi.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-ls-scfg-msi.c b/drivers/irqchip/irq-ls-scfg-msi.c
index c671b3212010..8099c5b1fcb5 100644
--- a/drivers/irqchip/irq-ls-scfg-msi.c
+++ b/drivers/irqchip/irq-ls-scfg-msi.c
@@ -100,7 +100,7 @@ static void ls_scfg_msi_compose_msg(struct irq_data *data, struct msi_msg *msg)
 		msg->data |= cpumask_first(mask);
 	}
 
-	iommu_dma_map_msi_msg(data->irq, msg);
+	iommu_dma_compose_msi_msg(data->irq, msg);
 }
 
 static int ls_scfg_msi_set_affinity(struct irq_data *irq_data,
@@ -141,6 +141,7 @@ static int ls_scfg_msi_domain_irq_alloc(struct irq_domain *domain,
 					unsigned int nr_irqs,
 					void *args)
 {
+	msi_alloc_info_t *info = args;
 	struct ls_scfg_msi *msi_data = domain->host_data;
 	int pos, err = 0;
 
@@ -157,6 +158,10 @@ static int ls_scfg_msi_domain_irq_alloc(struct irq_domain *domain,
 	if (err)
 		return err;
 
+	err = iommu_dma_prepare_msi(info->desc, msi_data->msiir_addr);
+	if (err)
+		return err;
+
 	irq_domain_set_info(domain, virq, pos,
 			    &ls_scfg_msi_parent_chip, msi_data,
 			    handle_simple_irq, NULL, NULL);
-- 
2.11.0