iommu/dma: Handle MSI mappings separately

MSI pages must always be mapped into a device's *current* domain, which
*might* be the default DMA domain, but might instead be a VFIO domain
with its own MSI cookie. This subtlety got accidentally lost in the
streamlining of __iommu_dma_map(), but rather than reintroduce more
complexity and/or special-casing, it turns out neater to just split this
path out entirely.

Since iommu_dma_get_msi_page() already duplicates much of what
__iommu_dma_map() does, it can easily just make the allocation and
mapping calls directly as well. That way we can further streamline the
helper back to exclusively operating on DMA domains.

Fixes: b61d271e ("iommu/dma: Move domain lookup into __iommu_dma_{map,unmap}")
Reported-by: NShameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reported-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NRobin Murphy <robin.murphy@arm.com>
Tested-by: NMarc Zyngier <maz@kernel.org>
Tested-by: NAndre Przywara <andre.przywara@arm.com>
Tested-by: NShameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Signed-off-by: NJoerg Roedel <jroedel@suse.de>

drivers/iommu/dma-iommu.c

@@ -459,13 +459,11 @@ static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
 {
 	struct iommu_domain *domain = iommu_get_dma_domain(dev);
 	struct iommu_dma_cookie *cookie = domain->iova_cookie;
-	size_t iova_off = 0;
+	struct iova_domain *iovad = &cookie->iovad;
+	size_t iova_off = iova_offset(iovad, phys);
 	dma_addr_t iova;
 
-	if (cookie->type == IOMMU_DMA_IOVA_COOKIE) {
-		iova_off = iova_offset(&cookie->iovad, phys);
-		size = iova_align(&cookie->iovad, size + iova_off);
-	}
+	size = iova_align(iovad, size + iova_off);
 
 	iova = iommu_dma_alloc_iova(domain, size, dma_get_mask(dev), dev);
 	if (!iova)
@@ -1147,16 +1145,21 @@ static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev,
 	if (!msi_page)
 		return NULL;
 
-	iova = __iommu_dma_map(dev, msi_addr, size, prot);
-	if (iova == DMA_MAPPING_ERROR)
+	iova = iommu_dma_alloc_iova(domain, size, dma_get_mask(dev), dev);
+	if (!iova)
 		goto out_free_page;
 
+	if (iommu_map(domain, iova, msi_addr, size, prot))
+		goto out_free_iova;
+
 	INIT_LIST_HEAD(&msi_page->list);
 	msi_page->phys = msi_addr;
 	msi_page->iova = iova;
 	list_add(&msi_page->list, &cookie->msi_page_list);
 	return msi_page;
 
+out_free_iova:
+	iommu_dma_free_iova(cookie, iova, size);
 out_free_page:
 	kfree(msi_page);
 	return NULL;