[PATCH 5.18 0254/1095] ACPI: VIOT: Fix ACS setup

Greg Kroah-Hartman
2022-08-15T20:43:19Z

From: Eric Auger <eric.auger@redhat.com>

[ Upstream commit 3dcb861dbc6ab101838a1548b1efddd00ca3c3ec ]

Currently acpi_viot_init() gets called after the pci
device has been scanned and pci_enable_acs() has been called.
So pci_request_acs() fails to be taken into account leading
to wrong single iommu group topologies when dealing with
multi-function root ports for instance.

We cannot simply move the acpi_viot_init() earlier, similarly
as the IORT init because the VIOT parsing relies on the pci
scan. However we can detect VIOT is present earlier and in
such a case, request ACS. Introduce a new acpi_viot_early_init()
routine that allows to call pci_request_acs() before the scan.

While at it, guard the call to pci_request_acs() with #ifdef
CONFIG_PCI.

Fixes: 3cf485540e7b ("ACPI: Add driver for the VIOT table")
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reported-by: Jin Liu <jinl@redhat.com>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Tested-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/acpi/bus.c | 1 +
drivers/acpi/viot.c | 26 ++++++++++++++++++++------
include/linux/acpi_viot.h | 2 ++
3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 6c735cfa7d43..ef7858393a3c 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -1373,6 +1373,7 @@ static int __init acpi_init(void)

pci_mmcfg_late_init();
acpi_iort_init();
+ acpi_viot_early_init();
acpi_hest_init();
acpi_ghes_init();
acpi_scan_init();
diff --git a/drivers/acpi/viot.c b/drivers/acpi/viot.c
index d2256326c73a..647f11cf165d 100644
--- a/drivers/acpi/viot.c
+++ b/drivers/acpi/viot.c
@@ -248,6 +248,26 @@ static int __init viot_parse_node(const struct acpi_viot_header *hdr)
return ret;
}

+/**
+ * acpi_viot_early_init - Test the presence of VIOT and enable ACS
+ *
+ * If the VIOT does exist, ACS must be enabled. This cannot be
+ * done in acpi_viot_init() which is called after the bus scan
+ */
+void __init acpi_viot_early_init(void)
+{
+#ifdef CONFIG_PCI
+ acpi_status status;
+ struct acpi_table_header *hdr;
+
+ status = acpi_get_table(ACPI_SIG_VIOT, 0, &hdr);
+ if (ACPI_FAILURE(status))
+ return;
+ pci_request_acs();
+ acpi_put_table(hdr);
+#endif
+}
+
/**
* acpi_viot_init - Parse the VIOT table
*
@@ -319,12 +339,6 @@ static int viot_pci_dev_iommu_init(struct pci_dev *pdev, u16 dev_id, void *data)
epid = ((domain_nr - ep->segment_start) << 16) +
dev_id - ep->bdf_start + ep->endpoint_id;

- /*
- * If we found a PCI range managed by the viommu, we're
- * the one that has to request ACS.
- */
- pci_request_acs();
-
return viot_dev_iommu_init(&pdev->dev, ep->viommu,
epid);
}
diff --git a/include/linux/acpi_viot.h b/include/linux/acpi_viot.h
index 1eb8ee5b0e5f..a5a122431563 100644
--- a/include/linux/acpi_viot.h
+++ b/include/linux/acpi_viot.h
@@ -6,9 +6,11 @@
#include <linux/acpi.h>

#ifdef CONFIG_ACPI_VIOT
+void __init acpi_viot_early_init(void);
void __init acpi_viot_init(void);
int viot_iommu_configure(struct device *dev);
#else
+static inline void acpi_viot_early_init(void) {}
static inline void acpi_viot_init(void) {}
static inline int viot_iommu_configure(struct device *dev)
{
--
2.35.1