[PATCH v3 0/7] iommu/dma-iommu: Split iommu_dma_map_msi_msg in two parts

[PATCH v3 0/7] iommu/dma-iommu: Split iommu_dma_map_msi_msg in two parts

[Julien Grall]

Hi all,

On RT, the function iommu_dma_map_msi_msg expects to be called from preemptible
context. However, this is not always the case resulting a splat with
!CONFIG_DEBUG_ATOMIC_SLEEP:

[   48.875777] BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:974
[   48.875779] in_atomic(): 1, irqs_disabled(): 128, pid: 2103, name: ip
[   48.875782] INFO: lockdep is turned off.
[   48.875784] irq event stamp: 10684
[   48.875786] hardirqs last  enabled at (10683): [<ffff0000110c8d70>] _raw_spin_unlock_irqrestore+0x88/0x90
[   48.875791] hardirqs last disabled at (10684): [<ffff0000110c8b2c>] _raw_spin_lock_irqsave+0x24/0x68
[   48.875796] softirqs last  enabled at (0): [<ffff0000100ec590>] copy_process.isra.1.part.2+0x8d8/0x1970
[   48.875801] softirqs last disabled at (0): [<0000000000000000>]           (null)
[   48.875805] Preemption disabled at:
[   48.875805] [<ffff000010189ae8>] __setup_irq+0xd8/0x6c0
[   48.875811] CPU: 2 PID: 2103 Comm: ip Not tainted 5.0.3-rt1-00007-g42ede9a0fed6 #45
[   48.875815] Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Jan 23 2017
[   48.875817] Call trace:
[   48.875818]  dump_backtrace+0x0/0x140
[   48.875821]  show_stack+0x14/0x20
[   48.875823]  dump_stack+0xa0/0xd4
[   48.875827]  ___might_sleep+0x16c/0x1f8
[   48.875831]  rt_spin_lock+0x5c/0x70
[   48.875835]  iommu_dma_map_msi_msg+0x5c/0x1d8
[   48.875839]  gicv2m_compose_msi_msg+0x3c/0x48
[   48.875843]  irq_chip_compose_msi_msg+0x40/0x58
[   48.875846]  msi_domain_activate+0x38/0x98
[   48.875849]  __irq_domain_activate_irq+0x58/0xa0
[   48.875852]  irq_domain_activate_irq+0x34/0x58
[   48.875855]  irq_activate+0x28/0x30
[   48.875858]  __setup_irq+0x2b0/0x6c0
[   48.875861]  request_threaded_irq+0xdc/0x188
[   48.875865]  sky2_setup_irq+0x44/0xf8
[   48.875868]  sky2_open+0x1a4/0x240
[   48.875871]  __dev_open+0xd8/0x188
[   48.875874]  __dev_change_flags+0x164/0x1f0
[   48.875877]  dev_change_flags+0x20/0x60
[   48.875879]  do_setlink+0x2a0/0xd30
[   48.875882]  __rtnl_newlink+0x5b4/0x6d8
[   48.875885]  rtnl_newlink+0x50/0x78
[   48.875888]  rtnetlink_rcv_msg+0x178/0x640
[   48.875891]  netlink_rcv_skb+0x58/0x118
[   48.875893]  rtnetlink_rcv+0x14/0x20
[   48.875896]  netlink_unicast+0x188/0x200
[   48.875898]  netlink_sendmsg+0x248/0x3d8
[   48.875900]  sock_sendmsg+0x18/0x40
[   48.875904]  ___sys_sendmsg+0x294/0x2d0
[   48.875908]  __sys_sendmsg+0x68/0xb8
[   48.875911]  __arm64_sys_sendmsg+0x20/0x28
[   48.875914]  el0_svc_common+0x90/0x118
[   48.875918]  el0_svc_handler+0x2c/0x80
[   48.875922]  el0_svc+0x8/0xc

Most of the patches have now been acked (missing a couple of ack from Joerg).

I was able to test the changes in GICv2m and GICv3 ITS. I don't have
hardware for the other interrupt controllers.

Cheers,

Julien Grall (7):
  genirq/msi: Add a new field in msi_desc to store an IOMMU cookie
  iommu/dma-iommu: Split iommu_dma_map_msi_msg() in two parts
  irqchip/gicv2m: Don't map the MSI page in gicv2m_compose_msi_msg()
  irqchip/gic-v3-its: Don't map the MSI page in
    its_irq_compose_msi_msg()
  irqchip/ls-scfg-msi: Don't map the MSI page in
    ls_scfg_msi_compose_msg()
  irqchip/gic-v3-mbi: Don't map the MSI page in mbi_compose_m{b,
    s}i_msg()
  iommu/dma-iommu: Remove iommu_dma_map_msi_msg()

 drivers/iommu/Kconfig             |  1 +
 drivers/iommu/dma-iommu.c         | 48 +++++++++++++++++++++++----------------
 drivers/irqchip/irq-gic-v2m.c     |  8 ++++++-
 drivers/irqchip/irq-gic-v3-its.c  |  7 +++++-
 drivers/irqchip/irq-gic-v3-mbi.c  | 15 ++++++++++--
 drivers/irqchip/irq-ls-scfg-msi.c |  7 +++++-
 include/linux/dma-iommu.h         | 24 ++++++++++++++++++--
 include/linux/msi.h               | 26 +++++++++++++++++++++
 kernel/irq/Kconfig                |  3 +++
 9 files changed, 112 insertions(+), 27 deletions(-)

-- 
2.11.0

[PATCH v3 1/7] genirq/msi: Add a new field in msi_desc to store an IOMMU cookie

[Julien Grall]

When an MSI doorbell is located downstream of an IOMMU, it is required
to swizzle the physical address with an appropriately-mapped IOVA for any
device attached to one of our DMA ops domain.

At the moment, the allocation of the mapping may be done when composing
the message. However, the composing may be done in non-preemtible
context while the allocation requires to be called from preemptible
context.

A follow-up change will split the current logic in two functions
requiring to keep an IOMMU cookie per MSI.

A new field is introduced in msi_desc to store an IOMMU cookie. As the
cookie may not be required in some configuration, the field is protected
under a new config CONFIG_IRQ_MSI_IOMMU.

A pair of helpers has also been introduced to access the field.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

---
    Changes in v3:
        - Add Robin's and Eric's reviewed-by

    Changes in v2:
        - Update the commit message to use imperative mood
        - Protect the field with a new config that will be selected by
        IOMMU_DMA later on
        - Add a set of helpers to access the new field
---
 include/linux/msi.h | 26 ++++++++++++++++++++++++++
 kernel/irq/Kconfig  |  3 +++
 2 files changed, 29 insertions(+)

diff --git a/include/linux/msi.h b/include/linux/msi.h
index 7e9b81c3b50d..82a308c19222 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -77,6 +77,9 @@ struct msi_desc {
 	struct device			*dev;
 	struct msi_msg			msg;
 	struct irq_affinity_desc	*affinity;
+#ifdef CONFIG_IRQ_MSI_IOMMU
+	const void			*iommu_cookie;
+#endif
 
 	union {
 		/* PCI MSI/X specific data */
@@ -119,6 +122,29 @@ struct msi_desc {
 #define for_each_msi_entry_safe(desc, tmp, dev)	\
 	list_for_each_entry_safe((desc), (tmp), dev_to_msi_list((dev)), list)
 
+#ifdef CONFIG_IRQ_MSI_IOMMU
+static inline const void *msi_desc_get_iommu_cookie(struct msi_desc *desc)
+{
+	return desc->iommu_cookie;
+}
+
+static inline void msi_desc_set_iommu_cookie(struct msi_desc *desc,
+					     const void *iommu_cookie)
+{
+	desc->iommu_cookie = iommu_cookie;
+}
+#else
+static inline const void *msi_desc_get_iommu_cookie(struct msi_desc *desc)
+{
+	return NULL;
+}
+
+static inline void msi_desc_set_iommu_cookie(struct msi_desc *desc,
+					     const void *iommu_cookie)
+{
+}
+#endif
+
 #ifdef CONFIG_PCI_MSI
 #define first_pci_msi_entry(pdev)	first_msi_entry(&(pdev)->dev)
 #define for_each_pci_msi_entry(desc, pdev)	\
diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index 5f3e2baefca9..8fee06625c37 100644
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -91,6 +91,9 @@ config GENERIC_MSI_IRQ_DOMAIN
 	select IRQ_DOMAIN_HIERARCHY
 	select GENERIC_MSI_IRQ
 
+config IRQ_MSI_IOMMU
+	bool
+
 config HANDLE_DOMAIN_IRQ
 	bool
 
-- 
2.11.0

[PATCH v3 2/7] iommu/dma-iommu: Split iommu_dma_map_msi_msg() in two parts

[Julien Grall]

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>

---
    Changes in v3:
        - Update the comment to use kerneldoc format
        - Fix typoes in the comments
        - More use of msi_desc_set_iommu_cookie
        - Add Robin's and Eric's reviewed-by

    Changes in v2:
        - Rework the commit message to use imperative mood
        - Use the MSI accessor to get/set the iommu cookie
        - Don't use ternary on return
        - Select CONFIG_IRQ_MSI_IOMMU
        - Pass an msi_desc rather than the irq number
---
 drivers/iommu/Kconfig     |  1 +
 drivers/iommu/dma-iommu.c | 46 +++++++++++++++++++++++++++++++++++++---------
 include/linux/dma-iommu.h | 25 +++++++++++++++++++++++++
 3 files changed, 63 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 6f07f3b21816..eb1c8cd243f9 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -94,6 +94,7 @@ config IOMMU_DMA
 	bool
 	select IOMMU_API
 	select IOMMU_IOVA
+	select IRQ_MSI_IOMMU
 	select NEED_SG_DMA_LENGTH
 
 config FSL_PAMU
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 77aabe637a60..f847904098f7 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -888,17 +888,18 @@ static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev,
 	return NULL;
 }
 
-void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg)
+int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
 {
-	struct device *dev = msi_desc_to_dev(irq_get_msi_desc(irq));
+	struct device *dev = msi_desc_to_dev(desc);
 	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
 	struct iommu_dma_cookie *cookie;
 	struct iommu_dma_msi_page *msi_page;
-	phys_addr_t msi_addr = (u64)msg->address_hi << 32 | msg->address_lo;
 	unsigned long flags;
 
-	if (!domain || !domain->iova_cookie)
-		return;
+	if (!domain || !domain->iova_cookie) {
+		desc->iommu_cookie = NULL;
+		return 0;
+	}
 
 	cookie = domain->iova_cookie;
 
@@ -911,7 +912,36 @@ void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg)
 	msi_page = iommu_dma_get_msi_page(dev, msi_addr, domain);
 	spin_unlock_irqrestore(&cookie->msi_lock, flags);
 
-	if (WARN_ON(!msi_page)) {
+	msi_desc_set_iommu_cookie(desc, msi_page);
+
+	if (!msi_page)
+		return -ENOMEM;
+	return 0;
+}
+
+void iommu_dma_compose_msi_msg(struct msi_desc *desc,
+			       struct msi_msg *msg)
+{
+	struct device *dev = msi_desc_to_dev(desc);
+	const struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
+	const struct iommu_dma_msi_page *msi_page;
+
+	msi_page = msi_desc_get_iommu_cookie(desc);
+
+	if (!domain || !domain->iova_cookie || WARN_ON(!msi_page))
+		return;
+
+	msg->address_hi = upper_32_bits(msi_page->iova);
+	msg->address_lo &= cookie_msi_granule(domain->iova_cookie) - 1;
+	msg->address_lo += lower_32_bits(msi_page->iova);
+}
+
+void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg)
+{
+	struct msi_desc *desc = irq_get_msi_desc(irq);
+	phys_addr_t msi_addr = (u64)msg->address_hi << 32 | msg->address_lo;
+
+	if (WARN_ON(iommu_dma_prepare_msi(desc, msi_addr))) {
 		/*
 		 * We're called from a void callback, so the best we can do is
 		 * 'fail' by filling the message with obviously bogus values.
@@ -922,8 +952,6 @@ void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg)
 		msg->address_lo = ~0U;
 		msg->data = ~0U;
 	} else {
-		msg->address_hi = upper_32_bits(msi_page->iova);
-		msg->address_lo &= cookie_msi_granule(cookie) - 1;
-		msg->address_lo += lower_32_bits(msi_page->iova);
+		iommu_dma_compose_msi_msg(desc, msg);
 	}
 }
diff --git a/include/linux/dma-iommu.h b/include/linux/dma-iommu.h
index e760dc5d1fa8..0b781a98ee73 100644
--- a/include/linux/dma-iommu.h
+++ b/include/linux/dma-iommu.h
@@ -71,12 +71,26 @@ void iommu_dma_unmap_resource(struct device *dev, dma_addr_t handle,
 		size_t size, enum dma_data_direction dir, unsigned long attrs);
 
 /* The DMA API isn't _quite_ the whole story, though... */
+/*
+ * iommu_dma_prepare_msi() - Map the MSI page in the IOMMU device
+ *
+ * The MSI page will be stored in @desc.
+ *
+ * Return: 0 on success otherwise an error describing the failure.
+ */
+int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr);
+
+/* Update the MSI message if required. */
+void iommu_dma_compose_msi_msg(struct msi_desc *desc,
+			       struct msi_msg *msg);
+
 void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg);
 void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list);
 
 #else
 
 struct iommu_domain;
+struct msi_desc;
 struct msi_msg;
 struct device;
 
@@ -99,6 +113,17 @@ static inline void iommu_put_dma_cookie(struct iommu_domain *domain)
 {
 }
 
+static inline int iommu_dma_prepare_msi(struct msi_desc *desc,
+					phys_addr_t msi_addr)
+{
+	return 0;
+}
+
+static inline void iommu_dma_compose_msi_msg(struct msi_desc *desc,
+					     struct msi_msg *msg)
+{
+}
+
 static inline void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg)
 {
 }
-- 
2.11.0

[PATCH v3 3/7] irqchip/gicv2m: Don't map the MSI page in gicv2m_compose_msi_msg()

[Julien Grall]

gicv2m_compose_msi_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 change split iommu_dma_map_msi_msg() in two new functions:
one that should be called in preemptible context, the other does
not have any requirement.

The GICv2m driver is reworked to avoid executing preemptible code in
non-preemptible context. This can be achieved by preparing the MSI
mapping when allocating the MSI interrupt.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

---
    Changes in v3:
        - Add Eric's reviewed-by

    Changes in v2:
        - Rework the commit message to use imperative mood
---
 drivers/irqchip/irq-gic-v2m.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v2m.c b/drivers/irqchip/irq-gic-v2m.c
index f5fe0100f9ff..4359f0583377 100644
--- a/drivers/irqchip/irq-gic-v2m.c
+++ b/drivers/irqchip/irq-gic-v2m.c
@@ -110,7 +110,7 @@ static void gicv2m_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
 	if (v2m->flags & GICV2M_NEEDS_SPI_OFFSET)
 		msg->data -= v2m->spi_offset;
 
-	iommu_dma_map_msi_msg(data->irq, msg);
+	iommu_dma_compose_msi_msg(irq_data_get_msi_desc(data), msg);
 }
 
 static struct irq_chip gicv2m_irq_chip = {
@@ -167,6 +167,7 @@ static void gicv2m_unalloc_msi(struct v2m_data *v2m, unsigned int hwirq,
 static int gicv2m_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
 				   unsigned int nr_irqs, void *args)
 {
+	msi_alloc_info_t *info = args;
 	struct v2m_data *v2m = NULL, *tmp;
 	int hwirq, offset, i, err = 0;
 
@@ -186,6 +187,11 @@ static int gicv2m_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
 
 	hwirq = v2m->spi_start + offset;
 
+	err = iommu_dma_prepare_msi(info->desc,
+				    v2m->res.start + V2M_MSI_SETSPI_NS);
+	if (err)
+		return err;
+
 	for (i = 0; i < nr_irqs; i++) {
 		err = gicv2m_irq_gic_domain_alloc(domain, virq + i, hwirq + i);
 		if (err)
-- 
2.11.0

[PATCH v3 4/7] irqchip/gic-v3-its: Don't map the MSI page in its_irq_compose_msi_msg()

[Julien Grall]

its_irq_compose_msi_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 change split iommu_dma_map_msi_msg() in two new functions:
one that should be called in preemptible context, the other does
not have any requirement.

The GICv3 ITS driver is reworked to avoid executing preemptible code in
non-preemptible context. This can be achieved by preparing the MSI
mapping when allocating the MSI interrupt.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

---
    Changes in v3:
        - Fix typo in the commit message
        - Check the return of iommu_dma_prepare_msi
        - Add Eric's reviewed-by

    Changes in v2:
        - Rework the commit message to use imperative mood
---
 drivers/irqchip/irq-gic-v3-its.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 7577755bdcf4..9cddf336c09d 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1179,7 +1179,7 @@ static void its_irq_compose_msi_msg(struct irq_data *d, struct msi_msg *msg)
 	msg->address_hi		= upper_32_bits(addr);
 	msg->data		= its_get_event_id(d);
 
-	iommu_dma_map_msi_msg(d->irq, msg);
+	iommu_dma_compose_msi_msg(irq_data_get_msi_desc(d), msg);
 }
 
 static int its_irq_set_irqchip_state(struct irq_data *d,
@@ -2566,6 +2566,7 @@ static int its_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
 {
 	msi_alloc_info_t *info = args;
 	struct its_device *its_dev = info->scratchpad[0].ptr;
+	struct its_node *its = its_dev->its;
 	irq_hw_number_t hwirq;
 	int err;
 	int i;
@@ -2574,6 +2575,10 @@ static int its_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
 	if (err)
 		return err;
 
+	err = iommu_dma_prepare_msi(info->desc, its->get_msi_base(its_dev));
+	if (err)
+		return err;
+
 	for (i = 0; i < nr_irqs; i++) {
 		err = its_irq_gic_domain_alloc(domain, virq + i, hwirq + i);
 		if (err)
-- 
2.11.0

[PATCH v3 5/7] irqchip/ls-scfg-msi: Don't map the MSI page in ls_scfg_msi_compose_msg()

[Julien Grall]

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 iommu_dma_map_msi_msg() in two new functions:
one that should be called in preemptible context, the other does
not have any requirement.

The FreeScale SCFG MSI driver is reworked to avoid executing preemptible
code in non-preemptible context. This can be achieved by preparing the
MSI maping when allocating the MSI interrupt.

Signed-off-by: Julien Grall <julien.grall@arm.com>

---
    Changes in v2:
        - Rework the commit message to use imperative mood
---
 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..669d29105772 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(irq_data_get_msi_desc(data), 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

[PATCH v3 6/7] irqchip/gic-v3-mbi: Don't map the MSI page in mbi_compose_m{b, s}i_msg()

[Julien Grall]

The functions mbi_compose_m{b, s}i_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 iommu_dma_map_msi_msg in two new functions:
one that should be called in preemptible context, the other does
not have any requirement.

The GICv3 MSI driver is reworked to avoid executing preemptible code in
non-preemptible context. This can be achieved by preparing the two MSI
mappings when allocating the MSI interrupt.

Signed-off-by: Julien Grall <julien.grall@arm.com>

---
    Changes in v2:
        - Rework the commit message to use imperative mood
---
 drivers/irqchip/irq-gic-v3-mbi.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-mbi.c b/drivers/irqchip/irq-gic-v3-mbi.c
index fbfa7ff6deb1..d50f6cdf043c 100644
--- a/drivers/irqchip/irq-gic-v3-mbi.c
+++ b/drivers/irqchip/irq-gic-v3-mbi.c
@@ -84,6 +84,7 @@ static void mbi_free_msi(struct mbi_range *mbi, unsigned int hwirq,
 static int mbi_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
 				   unsigned int nr_irqs, void *args)
 {
+	msi_alloc_info_t *info = args;
 	struct mbi_range *mbi = NULL;
 	int hwirq, offset, i, err = 0;
 
@@ -104,6 +105,16 @@ static int mbi_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
 
 	hwirq = mbi->spi_start + offset;
 
+	err = iommu_dma_prepare_msi(info->desc,
+				    mbi_phys_base + GICD_CLRSPI_NSR);
+	if (err)
+		return err;
+
+	err = iommu_dma_prepare_msi(info->desc,
+				    mbi_phys_base + GICD_SETSPI_NSR);
+	if (err)
+		return err;
+
 	for (i = 0; i < nr_irqs; i++) {
 		err = mbi_irq_gic_domain_alloc(domain, virq + i, hwirq + i);
 		if (err)
@@ -142,7 +153,7 @@ static void mbi_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
 	msg[0].address_lo = lower_32_bits(mbi_phys_base + GICD_SETSPI_NSR);
 	msg[0].data = data->parent_data->hwirq;
 
-	iommu_dma_map_msi_msg(data->irq, msg);
+	iommu_dma_compose_msi_msg(irq_data_get_msi_desc(data), msg);
 }
 
 #ifdef CONFIG_PCI_MSI
@@ -202,7 +213,7 @@ static void mbi_compose_mbi_msg(struct irq_data *data, struct msi_msg *msg)
 	msg[1].address_lo = lower_32_bits(mbi_phys_base + GICD_CLRSPI_NSR);
 	msg[1].data = data->parent_data->hwirq;
 
-	iommu_dma_map_msi_msg(data->irq, &msg[1]);
+	iommu_dma_compose_msi_msg(irq_data_get_msi_desc(data), &msg[1]);
 }
 
 /* Platform-MSI specific irqchip */
-- 
2.11.0

[PATCH v3 7/7] iommu/dma-iommu: Remove iommu_dma_map_msi_msg()

[Julien Grall]

A recent change split iommu_dma_map_msi_msg() in two new functions. The
function was still implemented to avoid modifying all the callers at
once.

Now that all the callers have been reworked, iommu_dma_map_msi_msg() can
be removed.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

---
    Changes in v3:
        - Add Robin's and Eric's reviewed-by

    Changes in v2:
        - Rework the commit message
---
 drivers/iommu/dma-iommu.c | 20 --------------------
 include/linux/dma-iommu.h |  5 -----
 2 files changed, 25 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index f847904098f7..13916fefeb27 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -935,23 +935,3 @@ void iommu_dma_compose_msi_msg(struct msi_desc *desc,
 	msg->address_lo &= cookie_msi_granule(domain->iova_cookie) - 1;
 	msg->address_lo += lower_32_bits(msi_page->iova);
 }
-
-void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg)
-{
-	struct msi_desc *desc = irq_get_msi_desc(irq);
-	phys_addr_t msi_addr = (u64)msg->address_hi << 32 | msg->address_lo;
-
-	if (WARN_ON(iommu_dma_prepare_msi(desc, msi_addr))) {
-		/*
-		 * We're called from a void callback, so the best we can do is
-		 * 'fail' by filling the message with obviously bogus values.
-		 * Since we got this far due to an IOMMU being present, it's
-		 * not like the existing address would have worked anyway...
-		 */
-		msg->address_hi = ~0U;
-		msg->address_lo = ~0U;
-		msg->data = ~0U;
-	} else {
-		iommu_dma_compose_msi_msg(desc, msg);
-	}
-}
diff --git a/include/linux/dma-iommu.h b/include/linux/dma-iommu.h
index 0b781a98ee73..476e0c54de2d 100644
--- a/include/linux/dma-iommu.h
+++ b/include/linux/dma-iommu.h
@@ -84,7 +84,6 @@ int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr);
 void iommu_dma_compose_msi_msg(struct msi_desc *desc,
 			       struct msi_msg *msg);
 
-void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg);
 void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list);
 
 #else
@@ -124,10 +123,6 @@ static inline void iommu_dma_compose_msi_msg(struct msi_desc *desc,
 {
 }
 
-static inline void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg)
-{
-}
-
 static inline void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list)
 {
 }
-- 
2.11.0

Re: [PATCH v3 2/7] iommu/dma-iommu: Split iommu_dma_map_msi_msg() in two parts

[Joerg Roedel]

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>

Re: [PATCH v3 7/7] iommu/dma-iommu: Remove iommu_dma_map_msi_msg()

[Joerg Roedel]

On Wed, May 01, 2019 at 02:58:24PM +0100, Julien Grall wrote:
> A recent change split iommu_dma_map_msi_msg() in two new functions. The
> function was still implemented to avoid modifying all the callers at
> once.
> 
> Now that all the callers have been reworked, iommu_dma_map_msi_msg() can
> be removed.
> 
> Signed-off-by: Julien Grall <julien.grall@arm.com>
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>

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

Re: [PATCH v3 6/7] irqchip/gic-v3-mbi: Don't map the MSI page in mbi_compose_m{b, s}i_msg()

[Marc Zyngier]

On 01/05/2019 14:58, Julien Grall wrote:
> The functions mbi_compose_m{b, s}i_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 iommu_dma_map_msi_msg in two new functions:
> one that should be called in preemptible context, the other does
> not have any requirement.
> 
> The GICv3 MSI driver is reworked to avoid executing preemptible code in
> non-preemptible context. This can be achieved by preparing the two MSI
> mappings when allocating the MSI interrupt.
> 
> Signed-off-by: Julien Grall <julien.grall@arm.com>
> 
> ---
>     Changes in v2:
>         - Rework the commit message to use imperative mood
> ---
>  drivers/irqchip/irq-gic-v3-mbi.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-mbi.c b/drivers/irqchip/irq-gic-v3-mbi.c
> index fbfa7ff6deb1..d50f6cdf043c 100644
> --- a/drivers/irqchip/irq-gic-v3-mbi.c
> +++ b/drivers/irqchip/irq-gic-v3-mbi.c
> @@ -84,6 +84,7 @@ static void mbi_free_msi(struct mbi_range *mbi, unsigned int hwirq,
>  static int mbi_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
>  				   unsigned int nr_irqs, void *args)
>  {
> +	msi_alloc_info_t *info = args;
>  	struct mbi_range *mbi = NULL;
>  	int hwirq, offset, i, err = 0;
>  
> @@ -104,6 +105,16 @@ static int mbi_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
>  
>  	hwirq = mbi->spi_start + offset;
>  
> +	err = iommu_dma_prepare_msi(info->desc,
> +				    mbi_phys_base + GICD_CLRSPI_NSR);
> +	if (err)
> +		return err;
> +
> +	err = iommu_dma_prepare_msi(info->desc,
> +				    mbi_phys_base + GICD_SETSPI_NSR);
> +	if (err)
> +		return err;

Nit here: The two registers are guaranteed to be in the same 4k page
(respectively offsets 0x48 and 0x40), so the second call is at best
useless. I'll fix it when applying it, no need to resend.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

Re: [PATCH v3 6/7] irqchip/gic-v3-mbi: Don't map the MSI page in mbi_compose_m{b, s}i_msg()

[Robin Murphy]

On 03/05/2019 15:27, Marc Zyngier wrote:
> On 01/05/2019 14:58, Julien Grall wrote:
>> The functions mbi_compose_m{b, s}i_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 iommu_dma_map_msi_msg in two new functions:
>> one that should be called in preemptible context, the other does
>> not have any requirement.
>>
>> The GICv3 MSI driver is reworked to avoid executing preemptible code in
>> non-preemptible context. This can be achieved by preparing the two MSI
>> mappings when allocating the MSI interrupt.
>>
>> Signed-off-by: Julien Grall <julien.grall@arm.com>
>>
>> ---
>>      Changes in v2:
>>          - Rework the commit message to use imperative mood
>> ---
>>   drivers/irqchip/irq-gic-v3-mbi.c | 15 +++++++++++++--
>>   1 file changed, 13 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/irqchip/irq-gic-v3-mbi.c b/drivers/irqchip/irq-gic-v3-mbi.c
>> index fbfa7ff6deb1..d50f6cdf043c 100644
>> --- a/drivers/irqchip/irq-gic-v3-mbi.c
>> +++ b/drivers/irqchip/irq-gic-v3-mbi.c
>> @@ -84,6 +84,7 @@ static void mbi_free_msi(struct mbi_range *mbi, unsigned int hwirq,
>>   static int mbi_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
>>   				   unsigned int nr_irqs, void *args)
>>   {
>> +	msi_alloc_info_t *info = args;
>>   	struct mbi_range *mbi = NULL;
>>   	int hwirq, offset, i, err = 0;
>>   
>> @@ -104,6 +105,16 @@ static int mbi_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
>>   
>>   	hwirq = mbi->spi_start + offset;
>>   
>> +	err = iommu_dma_prepare_msi(info->desc,
>> +				    mbi_phys_base + GICD_CLRSPI_NSR);
>> +	if (err)
>> +		return err;
>> +
>> +	err = iommu_dma_prepare_msi(info->desc,
>> +				    mbi_phys_base + GICD_SETSPI_NSR);
>> +	if (err)
>> +		return err;
> 
> Nit here: The two registers are guaranteed to be in the same 4k page
> (respectively offsets 0x48 and 0x40), so the second call is at best
> useless. I'll fix it when applying it, no need to resend.

Ack; the second call will simply find the existing page and overwrite 
desc->iommu_cookie with the same value. And if the two calls *did* ever 
come back with different pages, that logic would be quietly broken anyway.

Robin.