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

[Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>]

On 05/10/16 08:00, Nipun Gupta wrote:
> 
> 
>> -----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 <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
>> Acked-by: Marc Zyngier <marc.zyngier-5wv7dgnIgG8@public.gmane.org>
>> Signed-off-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
>> ---
>>  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));'

Er, yes... I fully agree. That's why it is exactly that.

> as __alloc_iova takes input parameter as 'struct iova_domain *'

Joking aside, though, I guess you've overlooked the change introduced by
c987ff0d3cb3 ("iommu/dma: Respect IOMMU aperture when allocating")?

Robin.

> 
> 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
>>
>> _______________________________________________
>> iommu mailing list
>> iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
>> https://lists.linuxfoundation.org/mailman/listinfo/iommu
>