[PATCH v6 4/5] PCI: Extend isolated function probing to s390

Niklas Schnelle
2022-06-28T14:31:17Z

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.

Cc: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
drivers/pci/probe.c | 2 +-
include/linux/hypervisor.h | 8 ++++++++
2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index a18e07e6a7df..156dd13594b8 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2667,7 +2667,7 @@ int pci_scan_slot(struct pci_bus *bus, int devfn)
* a hypervisor which passes through individual PCI
* functions.
*/
- if (!jailhouse_paravirt())
+ if (!hypervisor_isolated_pci_functions())
break;
}
fn = next_fn(bus, dev, fn);
diff --git a/include/linux/hypervisor.h b/include/linux/hypervisor.h
index fc08b433c856..33b1c0482aac 100644
--- a/include/linux/hypervisor.h
+++ b/include/linux/hypervisor.h
@@ -32,4 +32,12 @@ 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