ACPI: VIOT: Fix ACS setup

[ 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>

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index fc9bb06..7774b60 100644 (file)
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -1340,6 +1340,7 @@ static int __init acpi_init(void)
 
        pci_mmcfg_late_init();
        acpi_iort_init();
+       acpi_viot_early_init();
        acpi_hest_init();
        ghes_init();
        acpi_scan_init();

diff --git a/drivers/acpi/viot.c b/drivers/acpi/viot.c
index d225632..647f11c 100644 (file)
--- a/drivers/acpi/viot.c
+++ b/drivers/acpi/viot.c
@@ -249,6 +249,26 @@ err_free:
 }
 
 /**
+ * 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
  *
  * Parse the VIOT table, prepare the list of endpoints to be used during DMA
@@ -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 1eb8ee5..a5a1224 100644 (file)
--- 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)
 {