RE: [PATCH v7 21/22] iommu/dma: Add support for mapping MSIs

-----Original Message-----
From: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org [mailto:iommu-
bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org] On Behalf Of Robin Murphy
Sent: Monday, September 12, 2016 21:44
To: will.deacon-5wv7dgnIgG8@public.gmane.org; joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org; iommu-cunTk1MwBs/ROKNJybVBZg@public.gmane.org
foundation.org; linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; punit.agrawal-5wv7dgnIgG8@public.gmane.org;
thunder.leizhen-hv44wF8Li93QT0dZR+AlfA@public.gmane.org
Subject: [PATCH v7 21/22] iommu/dma: Add support for mapping MSIs

When an MSI doorbell is located downstream of an IOMMU, attaching devices
to a DMA ops domain and switching on translation leads to a rude shock when
their attempt to write to the physical address returned by the irqchip driver
faults (or worse, writes into some already-mapped
buffer) and no interrupt is forthcoming.

Address this by adding a hook for relevant irqchip drivers to call from their
compose_msi_msg() callback, to swizzle the physical address with an
appropriatly-mapped IOVA for any device attached to one of our DMA ops
domains.

Acked-by: Thomas Gleixner <redacted>
Acked-by: Marc Zyngier <redacted>
Signed-off-by: Robin Murphy <redacted>
---
 drivers/iommu/dma-iommu.c        | 136
++++++++++++++++++++++++++++++++++-----
 drivers/irqchip/irq-gic-v2m.c    |   3 +
 drivers/irqchip/irq-gic-v3-its.c |   3 +
 include/linux/dma-iommu.h        |   9 +++
 4 files changed, 136 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index

00c8a08d56e7..4329d18080cf 100644

--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c

@@ -25,10 +25,28 @@
 #include <linux/huge_mm.h>
 #include <linux/iommu.h>
 #include <linux/iova.h>
+#include <linux/irq.h>
 #include <linux/mm.h>
 #include <linux/scatterlist.h>
 #include <linux/vmalloc.h>

+struct iommu_dma_msi_page {
+	struct list_head	list;
+	dma_addr_t		iova;
+	phys_addr_t		phys;
+};
+
+struct iommu_dma_cookie {
+	struct iova_domain	iovad;
+	struct list_head	msi_page_list;
+	spinlock_t		msi_lock;
+};
+
+static inline struct iova_domain *cookie_iovad(struct iommu_domain
+*domain) {
+	return &((struct iommu_dma_cookie *)domain->iova_cookie)->iovad; }
+
 int iommu_dma_init(void)
 {
 	return iova_cache_get();

@@ -43,15 +61,19 @@ int iommu_dma_init(void)
  */
 int iommu_get_dma_cookie(struct iommu_domain *domain)  {
-	struct iova_domain *iovad;
+	struct iommu_dma_cookie *cookie;

 	if (domain->iova_cookie)
 		return -EEXIST;

-	iovad = kzalloc(sizeof(*iovad), GFP_KERNEL);
-	domain->iova_cookie = iovad;
+	cookie = kzalloc(sizeof(*cookie), GFP_KERNEL);
+	if (!cookie)
+		return -ENOMEM;

-	return iovad ? 0 : -ENOMEM;
+	spin_lock_init(&cookie->msi_lock);
+	INIT_LIST_HEAD(&cookie->msi_page_list);
+	domain->iova_cookie = cookie;
+	return 0;
 }
 EXPORT_SYMBOL(iommu_get_dma_cookie);

@@ -63,14 +85,20 @@ EXPORT_SYMBOL(iommu_get_dma_cookie);
  */
 void iommu_put_dma_cookie(struct iommu_domain *domain)  {
-	struct iova_domain *iovad = domain->iova_cookie;
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iommu_dma_msi_page *msi, *tmp;

-	if (!iovad)
+	if (!cookie)
 		return;

-	if (iovad->granule)
-		put_iova_domain(iovad);
-	kfree(iovad);
+	if (cookie->iovad.granule)
+		put_iova_domain(&cookie->iovad);
+
+	list_for_each_entry_safe(msi, tmp, &cookie->msi_page_list, list) {
+		list_del(&msi->list);
+		kfree(msi);
+	}
+	kfree(cookie);
 	domain->iova_cookie = NULL;
 }
 EXPORT_SYMBOL(iommu_put_dma_cookie);

@@ -88,7 +116,7 @@ EXPORT_SYMBOL(iommu_put_dma_cookie);
  */
 int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t

base, u64 size)  {
-	struct iova_domain *iovad = domain->iova_cookie;
+	struct iova_domain *iovad = cookie_iovad(domain);
 	unsigned long order, base_pfn, end_pfn;

 	if (!iovad)

@@ -155,7 +183,7 @@ int dma_direction_to_prot(enum dma_data_direction

dir, bool coherent)  static struct iova *__alloc_iova(struct iommu_domain
*domain, size_t size,
 		dma_addr_t dma_limit)
 {
-	struct iova_domain *iovad = domain->iova_cookie;
+	struct iova_domain *iovad = cookie_iovad(domain);
 	unsigned long shift = iova_shift(iovad);
 	unsigned long length = iova_align(iovad, size) >> shift;

@@ -171,7 +199,7 @@ static struct iova *__alloc_iova(struct iommu_domain

*domain, size_t size,
 /* The IOVA allocator knows what we mapped, so just unmap whatever that
was */  static void __iommu_dma_unmap(struct iommu_domain *domain,
dma_addr_t dma_addr)  {
-	struct iova_domain *iovad = domain->iova_cookie;
+	struct iova_domain *iovad = cookie_iovad(domain);
 	unsigned long shift = iova_shift(iovad);
 	unsigned long pfn = dma_addr >> shift;
 	struct iova *iova = find_iova(iovad, pfn); @@ -294,7 +322,7 @@ struct
page **iommu_dma_alloc(struct device *dev, size_t size, gfp_t gfp,
 		void (*flush_page)(struct device *, const void *, phys_addr_t))  {
 	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
-	struct iova_domain *iovad = domain->iova_cookie;
+	struct iova_domain *iovad = cookie_iovad(domain);
 	struct iova *iova;
 	struct page **pages;
 	struct sg_table sgt;

@@ -386,7 +414,7 @@ dma_addr_t iommu_dma_map_page(struct device

*dev, struct page *page,  {
 	dma_addr_t dma_addr;
 	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
-	struct iova_domain *iovad = domain->iova_cookie;
+	struct iova_domain *iovad = cookie_iovad(domain);
 	phys_addr_t phys = page_to_phys(page) + offset;
 	size_t iova_off = iova_offset(iovad, phys);
 	size_t len = iova_align(iovad, size + iova_off); @@ -495,7 +523,7 @@
int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
 		int nents, int prot)
 {
 	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
-	struct iova_domain *iovad = domain->iova_cookie;
+	struct iova_domain *iovad = cookie_iovad(domain);
 	struct iova *iova;
 	struct scatterlist *s, *prev = NULL;
 	dma_addr_t dma_addr;

@@ -587,3 +615,81 @@ int iommu_dma_mapping_error(struct device *dev,

dma_addr_t dma_addr)  {
 	return dma_addr == DMA_ERROR_CODE;
 }
+
+static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device
*dev,
+		phys_addr_t msi_addr, struct iommu_domain *domain) {
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iommu_dma_msi_page *msi_page;
+	struct iova_domain *iovad = &cookie->iovad;
+	struct iova *iova;
+	int prot = IOMMU_WRITE | IOMMU_NOEXEC | IOMMU_MMIO;
+
+	msi_addr &= ~(phys_addr_t)iova_mask(iovad);
+	list_for_each_entry(msi_page, &cookie->msi_page_list, list)
+		if (msi_page->phys == msi_addr)
+			return msi_page;
+
+	msi_page = kzalloc(sizeof(*msi_page), GFP_ATOMIC);
+	if (!msi_page)
+		return NULL;
+
+	iova = __alloc_iova(domain, iovad->granule, dma_get_mask(dev));

+	if (!iova)
+		goto out_free_page;
+
+	msi_page->phys = msi_addr;
+	msi_page->iova = iova_dma_addr(iovad, iova);
+	if (iommu_map(domain, msi_page->iova, msi_addr, iovad->granule,
prot))
+		goto out_free_iova;
+
+	INIT_LIST_HEAD(&msi_page->list);
+	list_add(&msi_page->list, &cookie->msi_page_list);
+	return msi_page;
+
+out_free_iova:
+	__free_iova(iovad, iova);
+out_free_page:
+	kfree(msi_page);
+	return NULL;
+}
+
+void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg) {
+	struct device *dev = msi_desc_to_dev(irq_get_msi_desc(irq));
+	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;
+
+	cookie = domain->iova_cookie;
+
+	/*
+	 * We disable IRQs to rule out a possible inversion against
+	 * irq_desc_lock if, say, someone tries to retarget the affinity
+	 * of an MSI from within an IPI handler.
+	 */
+	spin_lock_irqsave(&cookie->msi_lock, flags);
+	msi_page = iommu_dma_get_msi_page(dev, msi_addr, domain);
+	spin_unlock_irqrestore(&cookie->msi_lock, flags);
+
+	if (WARN_ON(!msi_page)) {
+		/*
+		 * 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 {
+		msg->address_hi = upper_32_bits(msi_page->iova);
+		msg->address_lo &= iova_mask(&cookie->iovad);
+		msg->address_lo += lower_32_bits(msi_page->iova);
+	}
+}

diff --git a/drivers/irqchip/irq-gic-v2m.c b/drivers/irqchip/irq-gic-v2m.c index

35eb7ac5d21f..863e073c6f7f 100644

--- a/drivers/irqchip/irq-gic-v2m.c
+++ b/drivers/irqchip/irq-gic-v2m.c

@@ -16,6 +16,7 @@
 #define pr_fmt(fmt) "GICv2m: " fmt

 #include <linux/acpi.h>
+#include <linux/dma-iommu.h>
 #include <linux/irq.h>
 #include <linux/irqdomain.h>
 #include <linux/kernel.h>

@@ -108,6 +109,8 @@ 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);
 }

 static struct irq_chip gicv2m_irq_chip = { diff --git a/drivers/irqchip/irq-gic-v3-
its.c b/drivers/irqchip/irq-gic-v3-its.c
index 36b9c28a5c91..98ff669d5962 100644

--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c

@@ -18,6 +18,7 @@
 #include <linux/bitmap.h>
 #include <linux/cpu.h>
 #include <linux/delay.h>
+#include <linux/dma-iommu.h>
 #include <linux/interrupt.h>
 #include <linux/log2.h>
 #include <linux/mm.h>

@@ -655,6 +656,8 @@ static void its_irq_compose_msi_msg(struct irq_data

*d, struct msi_msg *msg)
 	msg->address_lo		= addr & ((1UL << 32) - 1);
 	msg->address_hi		= addr >> 32;
 	msg->data		= its_get_event_id(d);
+
+	iommu_dma_map_msi_msg(d->irq, msg);
 }

 static struct irq_chip its_irq_chip = { diff --git a/include/linux/dma-iommu.h
b/include/linux/dma-iommu.h index 81c5c8d167ad..5ee806e41b5c 100644

--- a/include/linux/dma-iommu.h
+++ b/include/linux/dma-iommu.h

@@ -21,6 +21,7 @@

 #ifdef CONFIG_IOMMU_DMA
 #include <linux/iommu.h>
+#include <linux/msi.h>

 int iommu_dma_init(void);

@@ -62,9 +63,13 @@ void iommu_dma_unmap_sg(struct device *dev, struct

scatterlist *sg, int nents,  int iommu_dma_supported(struct device *dev, u64
mask);  int iommu_dma_mapping_error(struct device *dev, dma_addr_t
dma_addr);

+/* The DMA API isn't _quite_ the whole story, though... */ void
+iommu_dma_map_msi_msg(int irq, struct msi_msg *msg);
+
 #else

 struct iommu_domain;
+struct msi_msg;

 static inline int iommu_dma_init(void)
 {

@@ -80,6 +85,10 @@ static inline void iommu_put_dma_cookie(struct

iommu_domain *domain)  {  }

+static inline void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg)
+{ }
+
 #endif	/* CONFIG_IOMMU_DMA */
 #endif	/* __KERNEL__ */
 #endif	/* __DMA_IOMMU_H */
--
2.8.1.dirty

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