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Message-ID: <a580069c5e494ffffa668218b6fe3a207b01efec.1739005085.git.nicolinc@nvidia.com>
Date: Sat, 8 Feb 2025 01:02:34 -0800
From: Nicolin Chen <nicolinc@...dia.com>
To: <jgg@...dia.com>, <kevin.tian@...el.com>, <tglx@...utronix.de>,
<maz@...nel.org>
CC: <joro@...tes.org>, <will@...nel.org>, <robin.murphy@....com>,
<shuah@...nel.org>, <iommu@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>, <linux-kselftest@...r.kernel.org>,
<eric.auger@...hat.com>, <baolu.lu@...ux.intel.com>, <yi.l.liu@...el.com>,
<yury.norov@...il.com>, <jacob.pan@...ux.microsoft.com>,
<patches@...ts.linux.dev>
Subject: [PATCH v1 01/13] genirq/msi: Store the IOMMU IOVA directly in msi_desc instead of iommu_cookie
From: Jason Gunthorpe <jgg@...dia.com>
All the iommu cases simply want to override the MSI page's address with
the IOVA that was mapped through the iommu. This doesn't need a cookie
pointer, we just need to store the IOVA and its page size in the msi_desc.
Instead provide msi_desc_set_iommu_msi_iova() which allows the IOMMU side
to specify the IOVA that the MSI page is placed during
iommu_dma_prepare_msi(). This is stored in the msi_desc and then
iommu_dma_compose_msi_msg() is a simple inline that sets address_hi/lo.
The next patch will correct the naming.
This is done because we cannot correctly lock access to group->domain in
the atomic context that iommu_dma_compose_msi_msg() is called under. Today
the locking miss is tolerable because dma_iommu.c operates under an
assumption that the domain does not change while a driver is probed.
However iommufd now permits the domain to change while the driver is
probed and VFIO userspace can create races with IRQ changes calling
iommu_dma_prepare_msi/compose_msi_msg() and changing/freeing the
iommu_domain.
Removing the pointer, and critically, the call to
iommu_get_domain_for_dev() during compose resolves this race.
Signed-off-by: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
---
include/linux/iommu.h | 6 -----
include/linux/msi.h | 49 +++++++++++++++++++++++++--------------
drivers/iommu/dma-iommu.c | 30 ++++--------------------
3 files changed, 36 insertions(+), 49 deletions(-)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 38c65e92ecd0..caee952febd4 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -1508,7 +1508,6 @@ static inline void iommu_debugfs_setup(void) {}
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);
-void iommu_dma_compose_msi_msg(struct msi_desc *desc, struct msi_msg *msg);
#else /* CONFIG_IOMMU_DMA */
@@ -1524,11 +1523,6 @@ static inline int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_a
{
return 0;
}
-
-static inline void iommu_dma_compose_msi_msg(struct msi_desc *desc, struct msi_msg *msg)
-{
-}
-
#endif /* CONFIG_IOMMU_DMA */
/*
diff --git a/include/linux/msi.h b/include/linux/msi.h
index b10093c4d00e..74c6a823f157 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -166,6 +166,10 @@ struct msi_desc_data {
* @dev: Pointer to the device which uses this descriptor
* @msg: The last set MSI message cached for reuse
* @affinity: Optional pointer to a cpu affinity mask for this descriptor
+ * @iommu_msi_iova: Optional IOVA from the IOMMU to override the msi_addr.
+ * Only used if iommu_msi_page_shift != 0
+ * @iommu_msi_page_shift: Indicates how many bits of the original address
+ * should be preserved when using iommu_msi_iova.
* @sysfs_attr: Pointer to sysfs device attribute
*
* @write_msi_msg: Callback that may be called when the MSI message
@@ -184,7 +188,8 @@ struct msi_desc {
struct msi_msg msg;
struct irq_affinity_desc *affinity;
#ifdef CONFIG_IRQ_MSI_IOMMU
- const void *iommu_cookie;
+ u64 iommu_msi_iova : 58;
+ u64 iommu_msi_page_shift : 6;
#endif
#ifdef CONFIG_SYSFS
struct device_attribute *sysfs_attrs;
@@ -285,28 +290,36 @@ struct msi_desc *msi_next_desc(struct device *dev, unsigned int domid,
#define msi_desc_to_dev(desc) ((desc)->dev)
-#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)
+static inline void msi_desc_set_iommu_msi_iova(struct msi_desc *desc,
+ u64 msi_iova,
+ unsigned int page_shift)
{
- desc->iommu_cookie = iommu_cookie;
-}
-#else
-static inline const void *msi_desc_get_iommu_cookie(struct msi_desc *desc)
-{
- return NULL;
+#ifdef CONFIG_IRQ_MSI_IOMMU
+ desc->iommu_msi_iova = msi_iova >> page_shift;
+ desc->iommu_msi_page_shift = page_shift;
+#endif
}
-static inline void msi_desc_set_iommu_cookie(struct msi_desc *desc,
- const void *iommu_cookie)
+/**
+ * iommu_dma_compose_msi_msg() - Apply translation to an MSI message
+ * @desc: MSI descriptor prepared by iommu_dma_prepare_msi()
+ * @msg: MSI message containing target physical address
+ */
+static inline void iommu_dma_compose_msi_msg(struct msi_desc *desc,
+ struct msi_msg *msg)
{
-}
+#ifdef CONFIG_IRQ_MSI_IOMMU
+ if (desc->iommu_msi_page_shift) {
+ u64 msi_iova = desc->iommu_msi_iova
+ << desc->iommu_msi_page_shift;
+
+ msg->address_hi = upper_32_bits(msi_iova);
+ msg->address_lo = lower_32_bits(msi_iova) |
+ (msg->address_lo &
+ ((1 << desc->iommu_msi_page_shift) - 1));
+ }
#endif
+}
int msi_domain_insert_msi_desc(struct device *dev, unsigned int domid,
struct msi_desc *init_desc);
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 2a9fa0c8cc00..bf91e014d179 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1815,7 +1815,7 @@ int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
static DEFINE_MUTEX(msi_prepare_lock); /* see below */
if (!domain || !domain->iova_cookie) {
- desc->iommu_cookie = NULL;
+ msi_desc_set_iommu_msi_iova(desc, 0, 0);
return 0;
}
@@ -1827,33 +1827,13 @@ int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
mutex_lock(&msi_prepare_lock);
msi_page = iommu_dma_get_msi_page(dev, msi_addr, domain);
mutex_unlock(&msi_prepare_lock);
-
- msi_desc_set_iommu_cookie(desc, msi_page);
-
if (!msi_page)
return -ENOMEM;
- return 0;
-}
-/**
- * iommu_dma_compose_msi_msg() - Apply translation to an MSI message
- * @desc: MSI descriptor prepared by iommu_dma_prepare_msi()
- * @msg: MSI message containing target physical address
- */
-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);
+ msi_desc_set_iommu_msi_iova(
+ desc, msi_page->iova,
+ ilog2(cookie_msi_granule(domain->iova_cookie)));
+ return 0;
}
static int iommu_dma_init(void)
--
2.43.0
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