iommu/dma: Fix race condition during iova_domain initialization

When many devices share the same iova domain, iommu_dma_init_domain()
may be called at the same time. The checking of iovad->start_pfn will
all get false in iommu_dma_init_domain() and both enter init_iova_domain()
to do iovad initialization.

Fix this by protecting init_iova_domain() with iommu_dma_cookie->mutex.

Exception backtrace:
rb_insert_color(param1=0xFFFFFF80CD2BDB40, param3=1) + 64
init_iova_domain() + 180
iommu_setup_dma_ops() + 260
arch_setup_dma_ops() + 132
of_dma_configure_id() + 468
platform_dma_configure() + 32
really_probe() + 1168
driver_probe_device() + 268
__device_attach_driver() + 524
__device_attach() + 524
bus_probe_device() + 64
deferred_probe_work_func() + 260
process_one_work() + 580
worker_thread() + 1076
kthread() + 332
ret_from_fork() + 16

Signed-off-by: Ning Li <ning.li@mediatek.com>
Signed-off-by: Yunfei Wang <yf.wang@mediatek.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Miles Chen <miles.chen@mediatek.com>
Link: https://lore.kernel.org/r/20220530120748.31733-1-yf.wang@mediatek.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 9f9d9ba7f3769df14c3fc1caac70bddf36ca1c49..1910f4f1612b5de85b70be48bfc891c2632e4202 100644 (file)
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -64,6 +64,7 @@ struct iommu_dma_cookie {
 
        /* Domain for flush queue callback; NULL if flush queue not in use */
        struct iommu_domain             *fq_domain;
+       struct mutex                    mutex;
 };
 
 static DEFINE_STATIC_KEY_FALSE(iommu_deferred_attach_enabled);
@@ -310,6 +311,7 @@ int iommu_get_dma_cookie(struct iommu_domain *domain)
        if (!domain->iova_cookie)
                return -ENOMEM;
 
+       mutex_init(&domain->iova_cookie->mutex);
        return 0;
 }
 
@@ -560,26 +562,33 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
        }
 
        /* start_pfn is always nonzero for an already-initialised domain */
+       mutex_lock(&cookie->mutex);
        if (iovad->start_pfn) {
                if (1UL << order != iovad->granule ||
                    base_pfn != iovad->start_pfn) {
                        pr_warn("Incompatible range for DMA domain\n");
-                       return -EFAULT;
+                       ret = -EFAULT;
+                       goto done_unlock;
                }
 
-               return 0;
+               ret = 0;
+               goto done_unlock;
        }
 
        init_iova_domain(iovad, 1UL << order, base_pfn);
        ret = iova_domain_init_rcaches(iovad);
        if (ret)
-               return ret;
+               goto done_unlock;
 
        /* If the FQ fails we can simply fall back to strict mode */
        if (domain->type == IOMMU_DOMAIN_DMA_FQ && iommu_dma_init_fq(domain))
                domain->type = IOMMU_DOMAIN_DMA;
 
-       return iova_reserve_iommu_regions(dev, domain);
+       ret = iova_reserve_iommu_regions(dev, domain);
+
+done_unlock:
+       mutex_unlock(&cookie->mutex);
+       return ret;
 }
 
 /**