diff mbox series

[v2,3/7] iommu: Make iommu_dma_prepare_msi() into a generic operation

Message ID 4ca696150d2baee03af27c4ddefdb7b0b0280e7b.1740014950.git.nicolinc@nvidia.com (mailing list archive)
State New
Headers show
Series iommu: Add MSI mapping support with nested SMMU (Part-1 core) | expand

Commit Message

Nicolin Chen Feb. 20, 2025, 1:31 a.m. UTC 
From: Jason Gunthorpe <jgg@nvidia.com>

SW_MSI supports IOMMU to translate an MSI message before the MSI message
is delivered to the interrupt controller. On such systems, an iommu_domain
must have a translation for the MSI message for interrupts to work.

The IRQ subsystem will call into IOMMU to request that a physical page be
set up to receive MSI messages, and the IOMMU then sets an IOVA that maps
to that physical page. Ultimately the IOVA is programmed into the device
via the msi_msg.

Generalize this by allowing iommu_domain owners to provide implementations
of this mapping. Add a function pointer in struct iommu_domain to allow a
domain owner to provide its own implementation.

Have dma-iommu supply its implementation for IOMMU_DOMAIN_DMA types during
the iommu_get_dma_cookie() path. For IOMMU_DOMAIN_UNMANAGED types used by
VFIO (and iommufd for now), have the same iommu_dma_sw_msi set as well in
the iommu_get_msi_cookie() path.

Hold the group mutex while in iommu_dma_prepare_msi() to ensure the domain
doesn't change or become freed while running. Races with IRQ operations
from VFIO and domain changes from iommufd are possible here.

Replace the msi_prepare_lock with a lockdep assertion for the group mutex
as documentation. For the dmau_iommu.c each iommu_domain is unique to a
group.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 include/linux/iommu.h     | 44 ++++++++++++++++++++++++++-------------
 drivers/iommu/dma-iommu.c | 33 +++++++++++++----------------
 drivers/iommu/iommu.c     | 29 ++++++++++++++++++++++++++
 3 files changed, 73 insertions(+), 33 deletions(-)

Comments

Robin Murphy Feb. 21, 2025, 3:39 p.m. UTC | #1 
On 2025-02-20 1:31 am, Nicolin Chen wrote:
> From: Jason Gunthorpe <jgg@nvidia.com>
> 
> SW_MSI supports IOMMU to translate an MSI message before the MSI message
> is delivered to the interrupt controller. On such systems, an iommu_domain
> must have a translation for the MSI message for interrupts to work.
> 
> The IRQ subsystem will call into IOMMU to request that a physical page be
> set up to receive MSI messages, and the IOMMU then sets an IOVA that maps
> to that physical page. Ultimately the IOVA is programmed into the device
> via the msi_msg.
> 
> Generalize this by allowing iommu_domain owners to provide implementations
> of this mapping. Add a function pointer in struct iommu_domain to allow a
> domain owner to provide its own implementation.
> 
> Have dma-iommu supply its implementation for IOMMU_DOMAIN_DMA types during
> the iommu_get_dma_cookie() path. For IOMMU_DOMAIN_UNMANAGED types used by
> VFIO (and iommufd for now), have the same iommu_dma_sw_msi set as well in
> the iommu_get_msi_cookie() path.
> 
> Hold the group mutex while in iommu_dma_prepare_msi() to ensure the domain
> doesn't change or become freed while running. Races with IRQ operations
> from VFIO and domain changes from iommufd are possible here.
> 
> Replace the msi_prepare_lock with a lockdep assertion for the group mutex
> as documentation. For the dmau_iommu.c each iommu_domain is unique to a
> group.
> 
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>   include/linux/iommu.h     | 44 ++++++++++++++++++++++++++-------------
>   drivers/iommu/dma-iommu.c | 33 +++++++++++++----------------
>   drivers/iommu/iommu.c     | 29 ++++++++++++++++++++++++++
>   3 files changed, 73 insertions(+), 33 deletions(-)
> 
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index caee952febd4..761c5e186de9 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -44,6 +44,8 @@ struct iommu_dma_cookie;
>   struct iommu_fault_param;
>   struct iommufd_ctx;
>   struct iommufd_viommu;
> +struct msi_desc;
> +struct msi_msg;
>   
>   #define IOMMU_FAULT_PERM_READ	(1 << 0) /* read */
>   #define IOMMU_FAULT_PERM_WRITE	(1 << 1) /* write */
> @@ -216,6 +218,12 @@ struct iommu_domain {
>   	struct iommu_domain_geometry geometry;
>   	struct iommu_dma_cookie *iova_cookie;
>   	int (*iopf_handler)(struct iopf_group *group);
> +
> +#if IS_ENABLED(CONFIG_IRQ_MSI_IOMMU)
> +	int (*sw_msi)(struct iommu_domain *domain, struct msi_desc *desc,
> +		      phys_addr_t msi_addr);
> +#endif
> +
>   	void *fault_data;
>   	union {
>   		struct {
> @@ -234,6 +242,16 @@ struct iommu_domain {
>   	};
>   };
>   
> +static inline void iommu_domain_set_sw_msi(
> +	struct iommu_domain *domain,
> +	int (*sw_msi)(struct iommu_domain *domain, struct msi_desc *desc,
> +		      phys_addr_t msi_addr))
> +{
> +#if IS_ENABLED(CONFIG_IRQ_MSI_IOMMU)
> +	domain->sw_msi = sw_msi;
> +#endif
> +}

Yuck. Realistically we are going to have no more than two different 
implementations of this; a fiddly callback interface seems overkill. All 
we should need in the domain is a simple indicator of *which* MSI 
translation scheme is in use (if it can't be squeezed into the domain 
type itself), then iommu_dma_prepare_msi() can simply dispatch between 
iommu-dma and IOMMUFD based on that, and then it's easy to solve all the 
other fragility issues too.

Thanks,
Robin.

> +
>   static inline bool iommu_is_dma_domain(struct iommu_domain *domain)
>   {
>   	return domain->type & __IOMMU_DOMAIN_DMA_API;
> @@ -1470,6 +1488,18 @@ static inline ioasid_t iommu_alloc_global_pasid(struct device *dev)
>   static inline void iommu_free_global_pasid(ioasid_t pasid) {}
>   #endif /* CONFIG_IOMMU_API */
>   
> +#ifdef CONFIG_IRQ_MSI_IOMMU
> +#ifdef CONFIG_IOMMU_API
> +int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr);
> +#else
> +static inline int iommu_dma_prepare_msi(struct msi_desc *desc,
> +					phys_addr_t msi_addr)
> +{
> +	return 0;
> +}
> +#endif /* CONFIG_IOMMU_API */
> +#endif /* CONFIG_IRQ_MSI_IOMMU */
> +
>   #if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_IOMMU_API)
>   void iommu_group_mutex_assert(struct device *dev);
>   #else
> @@ -1503,26 +1533,12 @@ static inline void iommu_debugfs_setup(void) {}
>   #endif
>   
>   #ifdef CONFIG_IOMMU_DMA
> -#include <linux/msi.h>
> -
>   int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base);
> -
> -int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr);
> -
>   #else /* CONFIG_IOMMU_DMA */
> -
> -struct msi_desc;
> -struct msi_msg;
> -
>   static inline int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base)
>   {
>   	return -ENODEV;
>   }
> -
> -static inline int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
> -{
> -	return 0;
> -}
>   #endif	/* CONFIG_IOMMU_DMA */
>   
>   /*
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index bf91e014d179..3b58244e6344 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -24,6 +24,7 @@
>   #include <linux/memremap.h>
>   #include <linux/mm.h>
>   #include <linux/mutex.h>
> +#include <linux/msi.h>
>   #include <linux/of_iommu.h>
>   #include <linux/pci.h>
>   #include <linux/scatterlist.h>
> @@ -102,6 +103,9 @@ static int __init iommu_dma_forcedac_setup(char *str)
>   }
>   early_param("iommu.forcedac", iommu_dma_forcedac_setup);
>   
> +static int iommu_dma_sw_msi(struct iommu_domain *domain, struct msi_desc *desc,
> +			    phys_addr_t msi_addr);
> +
>   /* Number of entries per flush queue */
>   #define IOVA_DEFAULT_FQ_SIZE	256
>   #define IOVA_SINGLE_FQ_SIZE	32768
> @@ -398,6 +402,7 @@ int iommu_get_dma_cookie(struct iommu_domain *domain)
>   		return -ENOMEM;
>   
>   	mutex_init(&domain->iova_cookie->mutex);
> +	iommu_domain_set_sw_msi(domain, iommu_dma_sw_msi);
>   	return 0;
>   }
>   
> @@ -429,6 +434,7 @@ int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base)
>   
>   	cookie->msi_iova = base;
>   	domain->iova_cookie = cookie;
> +	iommu_domain_set_sw_msi(domain, iommu_dma_sw_msi);
>   	return 0;
>   }
>   EXPORT_SYMBOL(iommu_get_msi_cookie);
> @@ -443,6 +449,9 @@ void iommu_put_dma_cookie(struct iommu_domain *domain)
>   	struct iommu_dma_cookie *cookie = domain->iova_cookie;
>   	struct iommu_dma_msi_page *msi, *tmp;
>   
> +	if (domain->sw_msi != iommu_dma_sw_msi)
> +		return;
> +
>   	if (!cookie)
>   		return;
>   
> @@ -1800,33 +1809,19 @@ static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev,
>   	return NULL;
>   }
>   
> -/**
> - * iommu_dma_prepare_msi() - Map the MSI page in the IOMMU domain
> - * @desc: MSI descriptor, will store the MSI page
> - * @msi_addr: MSI target address to be mapped
> - *
> - * Return: 0 on success or negative error code if the mapping failed.
> - */
> -int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
> +static int iommu_dma_sw_msi(struct iommu_domain *domain, struct msi_desc *desc,
> +			    phys_addr_t msi_addr)
>   {
>   	struct device *dev = msi_desc_to_dev(desc);
> -	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
> -	struct iommu_dma_msi_page *msi_page;
> -	static DEFINE_MUTEX(msi_prepare_lock); /* see below */
> +	const struct iommu_dma_msi_page *msi_page;
>   
> -	if (!domain || !domain->iova_cookie) {
> +	if (!domain->iova_cookie) {
>   		msi_desc_set_iommu_msi_iova(desc, 0, 0);
>   		return 0;
>   	}
>   
> -	/*
> -	 * In fact the whole prepare operation should already be serialised by
> -	 * irq_domain_mutex further up the callchain, but that's pretty subtle
> -	 * on its own, so consider this locking as failsafe documentation...
> -	 */
> -	mutex_lock(&msi_prepare_lock);
> +	iommu_group_mutex_assert(dev);
>   	msi_page = iommu_dma_get_msi_page(dev, msi_addr, domain);
> -	mutex_unlock(&msi_prepare_lock);
>   	if (!msi_page)
>   		return -ENOMEM;
>   
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 870c3cdbd0f6..022bf96a18c5 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -3596,3 +3596,32 @@ int iommu_replace_group_handle(struct iommu_group *group,
>   	return ret;
>   }
>   EXPORT_SYMBOL_NS_GPL(iommu_replace_group_handle, "IOMMUFD_INTERNAL");
> +
> +#if IS_ENABLED(CONFIG_IRQ_MSI_IOMMU)
> +/**
> + * iommu_dma_prepare_msi() - Map the MSI page in the IOMMU domain
> + * @desc: MSI descriptor, will store the MSI page
> + * @msi_addr: MSI target address to be mapped
> + *
> + * The implementation of sw_msi() should take msi_addr and map it to
> + * an IOVA in the domain and call msi_desc_set_iommu_msi_iova() with the
> + * mapping information.
> + *
> + * Return: 0 on success or negative error code if the mapping failed.
> + */
> +int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
> +{
> +	struct device *dev = msi_desc_to_dev(desc);
> +	struct iommu_group *group = dev->iommu_group;
> +	int ret = 0;
> +
> +	if (!group)
> +		return 0;
> +
> +	mutex_lock(&group->mutex);
> +	if (group->domain && group->domain->sw_msi)
> +		ret = group->domain->sw_msi(group->domain, desc, msi_addr);
> +	mutex_unlock(&group->mutex);
> +	return ret;
> +}
> +#endif /* CONFIG_IRQ_MSI_IOMMU */
Jason Gunthorpe Feb. 21, 2025, 4:44 p.m. UTC | #2 
On Fri, Feb 21, 2025 at 03:39:45PM +0000, Robin Murphy wrote:
> Yuck. Realistically we are going to have no more than two different
> implementations of this; a fiddly callback interface seems overkill. All we
> should need in the domain is a simple indicator of *which* MSI translation
> scheme is in use (if it can't be squeezed into the domain type itself), then
> iommu_dma_prepare_msi() can simply dispatch between iommu-dma and IOMMUFD
> based on that, and then it's easy to solve all the other fragility issues
> too.

That would make module dependency problems, we have so far avoided
having the core kernel hard depend on iommufd.

Jason
diff mbox series

Patch

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index caee952febd4..761c5e186de9 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -44,6 +44,8 @@  struct iommu_dma_cookie;
 struct iommu_fault_param;
 struct iommufd_ctx;
 struct iommufd_viommu;
+struct msi_desc;
+struct msi_msg;
 
 #define IOMMU_FAULT_PERM_READ	(1 << 0) /* read */
 #define IOMMU_FAULT_PERM_WRITE	(1 << 1) /* write */
@@ -216,6 +218,12 @@  struct iommu_domain {
 	struct iommu_domain_geometry geometry;
 	struct iommu_dma_cookie *iova_cookie;
 	int (*iopf_handler)(struct iopf_group *group);
+
+#if IS_ENABLED(CONFIG_IRQ_MSI_IOMMU)
+	int (*sw_msi)(struct iommu_domain *domain, struct msi_desc *desc,
+		      phys_addr_t msi_addr);
+#endif
+
 	void *fault_data;
 	union {
 		struct {
@@ -234,6 +242,16 @@  struct iommu_domain {
 	};
 };
 
+static inline void iommu_domain_set_sw_msi(
+	struct iommu_domain *domain,
+	int (*sw_msi)(struct iommu_domain *domain, struct msi_desc *desc,
+		      phys_addr_t msi_addr))
+{
+#if IS_ENABLED(CONFIG_IRQ_MSI_IOMMU)
+	domain->sw_msi = sw_msi;
+#endif
+}
+
 static inline bool iommu_is_dma_domain(struct iommu_domain *domain)
 {
 	return domain->type & __IOMMU_DOMAIN_DMA_API;
@@ -1470,6 +1488,18 @@  static inline ioasid_t iommu_alloc_global_pasid(struct device *dev)
 static inline void iommu_free_global_pasid(ioasid_t pasid) {}
 #endif /* CONFIG_IOMMU_API */
 
+#ifdef CONFIG_IRQ_MSI_IOMMU
+#ifdef CONFIG_IOMMU_API
+int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr);
+#else
+static inline int iommu_dma_prepare_msi(struct msi_desc *desc,
+					phys_addr_t msi_addr)
+{
+	return 0;
+}
+#endif /* CONFIG_IOMMU_API */
+#endif /* CONFIG_IRQ_MSI_IOMMU */
+
 #if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_IOMMU_API)
 void iommu_group_mutex_assert(struct device *dev);
 #else
@@ -1503,26 +1533,12 @@  static inline void iommu_debugfs_setup(void) {}
 #endif
 
 #ifdef CONFIG_IOMMU_DMA
-#include <linux/msi.h>
-
 int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base);
-
-int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr);
-
 #else /* CONFIG_IOMMU_DMA */
-
-struct msi_desc;
-struct msi_msg;
-
 static inline int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base)
 {
 	return -ENODEV;
 }
-
-static inline int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
-{
-	return 0;
-}
 #endif	/* CONFIG_IOMMU_DMA */
 
 /*
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index bf91e014d179..3b58244e6344 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -24,6 +24,7 @@ 
 #include <linux/memremap.h>
 #include <linux/mm.h>
 #include <linux/mutex.h>
+#include <linux/msi.h>
 #include <linux/of_iommu.h>
 #include <linux/pci.h>
 #include <linux/scatterlist.h>
@@ -102,6 +103,9 @@  static int __init iommu_dma_forcedac_setup(char *str)
 }
 early_param("iommu.forcedac", iommu_dma_forcedac_setup);
 
+static int iommu_dma_sw_msi(struct iommu_domain *domain, struct msi_desc *desc,
+			    phys_addr_t msi_addr);
+
 /* Number of entries per flush queue */
 #define IOVA_DEFAULT_FQ_SIZE	256
 #define IOVA_SINGLE_FQ_SIZE	32768
@@ -398,6 +402,7 @@  int iommu_get_dma_cookie(struct iommu_domain *domain)
 		return -ENOMEM;
 
 	mutex_init(&domain->iova_cookie->mutex);
+	iommu_domain_set_sw_msi(domain, iommu_dma_sw_msi);
 	return 0;
 }
 
@@ -429,6 +434,7 @@  int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base)
 
 	cookie->msi_iova = base;
 	domain->iova_cookie = cookie;
+	iommu_domain_set_sw_msi(domain, iommu_dma_sw_msi);
 	return 0;
 }
 EXPORT_SYMBOL(iommu_get_msi_cookie);
@@ -443,6 +449,9 @@  void iommu_put_dma_cookie(struct iommu_domain *domain)
 	struct iommu_dma_cookie *cookie = domain->iova_cookie;
 	struct iommu_dma_msi_page *msi, *tmp;
 
+	if (domain->sw_msi != iommu_dma_sw_msi)
+		return;
+
 	if (!cookie)
 		return;
 
@@ -1800,33 +1809,19 @@  static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev,
 	return NULL;
 }
 
-/**
- * iommu_dma_prepare_msi() - Map the MSI page in the IOMMU domain
- * @desc: MSI descriptor, will store the MSI page
- * @msi_addr: MSI target address to be mapped
- *
- * Return: 0 on success or negative error code if the mapping failed.
- */
-int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
+static int iommu_dma_sw_msi(struct iommu_domain *domain, struct msi_desc *desc,
+			    phys_addr_t msi_addr)
 {
 	struct device *dev = msi_desc_to_dev(desc);
-	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
-	struct iommu_dma_msi_page *msi_page;
-	static DEFINE_MUTEX(msi_prepare_lock); /* see below */
+	const struct iommu_dma_msi_page *msi_page;
 
-	if (!domain || !domain->iova_cookie) {
+	if (!domain->iova_cookie) {
 		msi_desc_set_iommu_msi_iova(desc, 0, 0);
 		return 0;
 	}
 
-	/*
-	 * In fact the whole prepare operation should already be serialised by
-	 * irq_domain_mutex further up the callchain, but that's pretty subtle
-	 * on its own, so consider this locking as failsafe documentation...
-	 */
-	mutex_lock(&msi_prepare_lock);
+	iommu_group_mutex_assert(dev);
 	msi_page = iommu_dma_get_msi_page(dev, msi_addr, domain);
-	mutex_unlock(&msi_prepare_lock);
 	if (!msi_page)
 		return -ENOMEM;
 
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 870c3cdbd0f6..022bf96a18c5 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3596,3 +3596,32 @@  int iommu_replace_group_handle(struct iommu_group *group,
 	return ret;
 }
 EXPORT_SYMBOL_NS_GPL(iommu_replace_group_handle, "IOMMUFD_INTERNAL");
+
+#if IS_ENABLED(CONFIG_IRQ_MSI_IOMMU)
+/**
+ * iommu_dma_prepare_msi() - Map the MSI page in the IOMMU domain
+ * @desc: MSI descriptor, will store the MSI page
+ * @msi_addr: MSI target address to be mapped
+ *
+ * The implementation of sw_msi() should take msi_addr and map it to
+ * an IOVA in the domain and call msi_desc_set_iommu_msi_iova() with the
+ * mapping information.
+ *
+ * Return: 0 on success or negative error code if the mapping failed.
+ */
+int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
+{
+	struct device *dev = msi_desc_to_dev(desc);
+	struct iommu_group *group = dev->iommu_group;
+	int ret = 0;
+
+	if (!group)
+		return 0;
+
+	mutex_lock(&group->mutex);
+	if (group->domain && group->domain->sw_msi)
+		ret = group->domain->sw_msi(group->domain, desc, msi_addr);
+	mutex_unlock(&group->mutex);
+	return ret;
+}
+#endif /* CONFIG_IRQ_MSI_IOMMU */