[RESEND PATCH V3 2/2] iommu: sprd: Add support for reattaching an existing domain

Chunyan Zhang
2023-03-31T03:32:06Z

This IOMMU driver should allow a domain to be attached more than once.

If IOMMU is reattaching to the same domain which is attached, there's
nothing to be done.

If reattching to a previously-used domain, do not alloc DMA buffer
again which stores address mapping table to avoid memory leak.

Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
---
drivers/iommu/sprd-iommu.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/sprd-iommu.c b/drivers/iommu/sprd-iommu.c
index 7df1f730c778..3513b2b108bf 100644
--- a/drivers/iommu/sprd-iommu.c
+++ b/drivers/iommu/sprd-iommu.c
@@ -62,6 +62,7 @@ enum sprd_iommu_version {
* @eb: gate clock which controls IOMMU access
*/
struct sprd_iommu_device {
+ struct sprd_iommu_domain *dom;
enum sprd_iommu_version ver;
u32 *prot_page_va;
dma_addr_t prot_page_pa;
@@ -252,15 +253,27 @@ static int sprd_iommu_attach_device(struct iommu_domain *domain,
struct sprd_iommu_domain *dom = to_sprd_domain(domain);
size_t pgt_size = sprd_iommu_pgt_size(domain);

- if (dom->sdev)
- return -EINVAL;
+ /* The device is attached to this domain */
+ if (sdev->dom == dom)
+ return 0;

- dom->pgt_va = dma_alloc_coherent(sdev->dev, pgt_size, &dom->pgt_pa, GFP_KERNEL);
- if (!dom->pgt_va)
- return -ENOMEM;
+ /* The first time that domain is attaching to a device */
+ if (!dom->pgt_va) {
+ dom->pgt_va = dma_alloc_coherent(sdev->dev, pgt_size, &dom->pgt_pa, GFP_KERNEL);
+ if (!dom->pgt_va)
+ return -ENOMEM;
+
+ dom->sdev = sdev;
+ }

- dom->sdev = sdev;
+ sdev->dom = dom;

+ /*
+ * One sprd IOMMU serves one client device only, disabled it before
+ * configure mapping table to avoid access conflict in case other
+ * mapping table is stored in.
+ */
+ sprd_iommu_hw_en(sdev, false);
sprd_iommu_first_ppn(dom);
sprd_iommu_first_vpn(dom);
sprd_iommu_vpn_range(dom);
--
2.25.1