[PATCH v2] iommu/of: Fix pci_request_acs() before enumerating PCI devices

Wang Xingang
2021-05-17T13:17:17Z

From: Xingang Wang <wangxingang5@huawei.com>

When booting with devicetree, the pci_request_acs() is called after the
enumeration and initialization of PCI devices, thus the ACS is not
enabled. This patch add check for IOMMU in of_core_init(), and call
pci_request_acs() when iommu is detected, making sure that the ACS will
be enabled.

Fixes: 6bf6c24720d33 ("iommu/of: Request ACS from the PCI core when
configuring IOMMU linkage")
Signed-off-by: Xingang Wang <wangxingang5@huawei.com>
---
drivers/iommu/of_iommu.c | 1 -
drivers/of/base.c | 9 ++++++++-
2 files changed, 8 insertions(+), 2 deletions(-)

Change log:
v1->v2:
- remove pci_request_acs() in of_iommu_configure
- check and call pci_request_acs() in of_core_init()

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index a9d2df001149..54a14da242cc 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -205,7 +205,6 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
.np = master_np,
};

- pci_request_acs();
err = pci_for_each_dma_alias(to_pci_dev(dev),
of_pci_iommu_init, &info);
} else {
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 48e941f99558..95cd8f0e5435 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -24,6 +24,7 @@
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_graph.h>
+#include <linux/pci.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/string.h>
@@ -166,7 +167,7 @@ void __of_phandle_cache_inv_entry(phandle handle)
void __init of_core_init(void)
{
struct device_node *np;
-
+ bool of_iommu_detect = false;

/* Create the kset, and register existing nodes */
mutex_lock(&of_mutex);
@@ -180,6 +181,12 @@ void __init of_core_init(void)
__of_attach_node_sysfs(np);
if (np->phandle && !phandle_cache[of_phandle_cache_hash(np->phandle)])
phandle_cache[of_phandle_cache_hash(np->phandle)] = np;
+
+ /* Detect IOMMU and make sure ACS will be enabled */
+ if (!of_iommu_detect && of_get_property(np, "iommu-map", NULL)) {
+ of_iommu_detect = true;
+ pci_request_acs();
+ }
}
mutex_unlock(&of_mutex);

--
2.19.1