[tip:x86/platform] x86/jailhouse: Respect pci=lastbus command line settings

[tip-bot for Jan Kiszka]

Commit-ID:  3b42349d56c96e144401d2317d8eeb9937511423
Gitweb:     https://git.kernel.org/tip/3b42349d56c96e144401d2317d8eeb9937511423
Author:     Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
AuthorDate: Fri, 19 Jan 2018 11:06:30 +0100
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Sat, 20 Jan 2018 08:15:44 +0100

x86/jailhouse: Respect pci=lastbus command line settings

Limiting the scan width to the known last bus via the command line can
accelerate the boot noteworthy.

Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Jailhouse <jailhouse-dev@xxxxxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/51f5fe62-ca8f-9286-5cdb-39df3fad78b4@xxxxxxxxxxx

---
 arch/x86/kernel/jailhouse.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/jailhouse.c b/arch/x86/kernel/jailhouse.c
index 2b7ebbe..b68fd89 100644
--- a/arch/x86/kernel/jailhouse.c
+++ b/arch/x86/kernel/jailhouse.c
@@ -119,8 +119,10 @@ static int __init jailhouse_pci_arch_init(void)
 	/*
 	 * There are no bridges on the virtual PCI root bus under Jailhouse,
 	 * thus no other way to discover all devices than a full scan.
+	 * Respect any overrides via the command line, though.
 	 */
-	pcibios_last_bus = 0xff;
+	if (pcibios_last_bus < 0)
+		pcibios_last_bus = 0xff;
 
 	return 0;
 }