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From:   Niklas Schnelle <schnelle@linux.ibm.com>
To:     Bjorn Helgaas <bhelgaas@google.com>,
        Jan Kiszka <jan.kiszka@siemens.com>,
        Matthew Rosato <mjrosato@linux.ibm.com>,
        Pierre Morel <pmorel@linux.ibm.com>
Cc:     linux-s390@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH RESEND v5 3/4] PCI: Extend isolated function probing to s390
Date:   Thu,  2 Jun 2022 12:30:15 +0200
Message-Id: <20220602103016.1499031-4-schnelle@linux.ibm.com>
In-Reply-To: <20220602103016.1499031-1-schnelle@linux.ibm.com>
References: <20220602103016.1499031-1-schnelle@linux.ibm.com>
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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 3029edc68ff7..4e27cc929095 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2663,7 +2663,7 @@ 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