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

Nipun Gupta nipun.gupta at nxp.com
Wed Oct 5 00:00:42 PDT 2016



> -----Original Message-----
> From: iommu-bounces at lists.linux-foundation.org [mailto:iommu-
> bounces at lists.linux-foundation.org] On Behalf Of Robin Murphy
> Sent: Monday, September 12, 2016 21:44
> To: will.deacon at arm.com; joro at 8bytes.org; iommu at lists.linux-
> foundation.org; linux-arm-kernel at lists.infradead.org
> Cc: devicetree at vger.kernel.org; punit.agrawal at arm.com;
> thunder.leizhen at huawei.com
> 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 <tglx at linutronix.de>
> Acked-by: Marc Zyngier <marc.zyngier at arm.com>
> Signed-off-by: Robin Murphy <robin.murphy at arm.com>
> ---
>  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));

I think this should be 'iova = __alloc_iova(domain, iovad->granule, dma_get_mask(dev));'
as __alloc_iova takes input parameter as 'struct iova_domain *'

Regards,
Nipun

> +	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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