diff mbox series

[v2] ACPI: VIOT: Fix ACS setup

Message ID 20220630094059.1204283-1-eric.auger@redhat.com
State Accepted
Commit 3dcb861dbc6ab101838a1548b1efddd00ca3c3ec
Headers show
Series [v2] ACPI: VIOT: Fix ACS setup | expand

Commit Message

Eric Auger June 30, 2022, 9:40 a.m. UTC
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>

---

v1 -> v2:
- guard acpi_viot_early_init() content with #ifdef CONFIG_PCI
- do not call acpi_put_table() if acpi_get_table() failed
- change declaration order of acpi_viot_early_init() stub
---
 drivers/acpi/bus.c        |  1 +
 drivers/acpi/viot.c       | 26 ++++++++++++++++++++------
 include/linux/acpi_viot.h |  2 ++
 3 files changed, 23 insertions(+), 6 deletions(-)

Comments

Rafael J. Wysocki July 5, 2022, 6:27 p.m. UTC | #1
On Thu, Jun 30, 2022 at 11:59 AM Jean-Philippe Brucker
<jean-philippe@linaro.org> wrote:
>
> On Thu, Jun 30, 2022 at 11:40:59AM +0200, Eric Auger wrote:
> > 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>

Applied as 5.20 material, thanks!
diff mbox series

Patch

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 86fa61a21826..906ad8153fd9 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -1400,6 +1400,7 @@  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)
 {