[PATCH v2] powerpc: iommu: Bring back table group release_ownership() call

From: Shivaprasad G Bhat
Date: Fri Jan 26 2024 - 10:10:09 EST


The commit 2ad56efa80db ("powerpc/iommu: Setup a default domain and
remove set_platform_dma_ops") refactored the code removing the
set_platform_dma_ops(). It missed out the table group
release_ownership() call which would have got called otherwise
during the guest shutdown via vfio_group_detach_container(). On
PPC64, this particular call actually sets up the 32-bit TCE table,
and enables the 64-bit DMA bypass etc. Now after guest shutdown,
the subsequent host driver (e.g megaraid-sas) probe post unbind
from vfio-pci fails like,

megaraid_sas 0031:01:00.0: Warning: IOMMU dma not supported: mask 0x7fffffffffffffff, table unavailable
megaraid_sas 0031:01:00.0: Warning: IOMMU dma not supported: mask 0xffffffff, table unavailable
megaraid_sas 0031:01:00.0: Failed to set DMA mask
megaraid_sas 0031:01:00.0: Failed from megasas_init_fw 6539

The patch brings back the call to table_group release_ownership()
call when switching back to PLATFORM domain from BLOCKED, while
also separates the domain_ops for both.

Fixes: 2ad56efa80db ("powerpc/iommu: Setup a default domain and remove set_platform_dma_ops")
Signed-off-by: Shivaprasad G Bhat <sbhat@xxxxxxxxxxxxx>
---
Changelog:
v1: https://lore.kernel.org/linux-iommu/170618451433.3805.9015493852395837391.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
- Split the common attach_dev call to platform and blocked attach_dev
calls as suggested.

arch/powerpc/kernel/iommu.c | 37 ++++++++++++++++++++++++++++---------
1 file changed, 28 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index ebe259bdd462..d71eac3b2887 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -1287,20 +1287,20 @@ spapr_tce_platform_iommu_attach_dev(struct iommu_domain *platform_domain,
struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
struct iommu_group *grp = iommu_group_get(dev);
struct iommu_table_group *table_group;
- int ret = -EINVAL;

/* At first attach the ownership is already set */
if (!domain)
return 0;

- if (!grp)
- return -ENODEV;
-
table_group = iommu_group_get_iommudata(grp);
- ret = table_group->ops->take_ownership(table_group);
+ /*
+ * The domain being set to PLATFORM from earlier
+ * BLOCKED. The table_group ownership has to be released.
+ */
+ table_group->ops->release_ownership(table_group);
iommu_group_put(grp);

- return ret;
+ return 0;
}

static const struct iommu_domain_ops spapr_tce_platform_domain_ops = {
@@ -1312,13 +1312,32 @@ static struct iommu_domain spapr_tce_platform_domain = {
.ops = &spapr_tce_platform_domain_ops,
};

-static struct iommu_domain spapr_tce_blocked_domain = {
- .type = IOMMU_DOMAIN_BLOCKED,
+static int
+spapr_tce_blocked_iommu_attach_dev(struct iommu_domain *platform_domain,
+ struct device *dev)
+{
+ struct iommu_group *grp = iommu_group_get(dev);
+ struct iommu_table_group *table_group;
+ int ret = -EINVAL;
+
/*
* FIXME: SPAPR mixes blocked and platform behaviors, the blocked domain
* also sets the dma_api ops
*/
- .ops = &spapr_tce_platform_domain_ops,
+ table_group = iommu_group_get_iommudata(grp);
+ ret = table_group->ops->take_ownership(table_group);
+ iommu_group_put(grp);
+
+ return ret;
+}
+
+static const struct iommu_domain_ops spapr_tce_blocked_domain_ops = {
+ .attach_dev = spapr_tce_blocked_iommu_attach_dev,
+};
+
+static struct iommu_domain spapr_tce_blocked_domain = {
+ .type = IOMMU_DOMAIN_BLOCKED,
+ .ops = &spapr_tce_blocked_domain_ops,
};

static bool spapr_tce_iommu_capable(struct device *dev, enum iommu_cap cap)