[PATCH v2 3/4] PCI: Extend isolated function probing to s390

Niklas Schnelle
2022-04-12T14:30:54Z

Like the jailhouse hypervisor s390's PCI architecture allows passing
isolated PCI functions to an OS instance. As of now this is was not
utilized even with multi-function support as the s390 PCI code makes
sure that only virtual PCI busses including a function with devfn 0 are
presented to the PCI subsystem. A subsequent change will remove this
restriction.

Allow probing such functions by replacing the existing check for
jailhouse_paravirt() with a new hypervisor_isolated_pci_functions()
helper.

Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
drivers/pci/probe.c | 8 ++++----
include/linux/hypervisor.h | 9 +++++++++
2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 8100e044dfc5..a57ea0ff1470 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2602,11 +2602,11 @@ static int next_fn(struct pci_bus *bus, struct pci_dev *dev, int fn)
if (dev && !dev->multifunction)
return -ENODEV;
/*
- * Usually a function 0 is required but the jailhouse hypervisor may
- * pass individual functions. For non-contiguous multifunction devices
- * some functions may also be missing.
+ * Usually a function 0 is required but some hypervisors may pass
+ * individual functions. For non-contiguous multifunction devices some
+ * functions may also be missing.
*/
- if (!fn && !dev && !jailhouse_paravirt())
+ if (!fn && !dev && !hypervisor_isolated_pci_functions())
return -ENODEV;
return (fn <= 6) ? fn + 1 : -ENODEV;
}
diff --git a/include/linux/hypervisor.h b/include/linux/hypervisor.h
index fc08b433c856..52abd459f9a3 100644
--- a/include/linux/hypervisor.h
+++ b/include/linux/hypervisor.h
@@ -32,4 +32,13 @@ static inline bool jailhouse_paravirt(void)

#endif /* !CONFIG_X86 */

+static inline bool hypervisor_isolated_pci_functions(void)
+{
+ if (IS_ENABLED(CONFIG_S390))
+ return true;
+ else
+ return jailhouse_paravirt();
+}
+
+
#endif /* __LINUX_HYPEVISOR_H */
--
2.32.0