diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 9abaec0703ef..9a07eb39336e 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -2204,6 +2204,19 @@ static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev,
 	dma_addr_t iova;
 	int prot = IOMMU_WRITE | IOMMU_NOEXEC | IOMMU_MMIO;
 	size_t size = cookie_msi_granule(domain);
+	static DEFINE_MUTEX(msi_prepare_lock);
+
+	/*
+	 * Normally a device's default domain is only ever attached to that
+	 * device's own group, and the group mutex held by
+	 * iommu_group_mutex_assert()'s callers is enough on its own. A VFIO
+	 * type1 container is the one case that breaks that assumption: it
+	 * can merge devices from different groups onto one domain, so two
+	 * devices' group mutexes don't serialize each other here. A static
+	 * lock is sufficient due to the expectation that this is a corner
+	 * case that will never be contended in practice.
+	 */
+	guard(mutex)(&msi_prepare_lock);
 
 	msi_addr &= ~(phys_addr_t)(size - 1);
 	list_for_each_entry(msi_page, msi_page_list, list)