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Subject[PATCH AUTOSEL 4.19 156/191] x86/hyperv: Suppress "PCI: Fatal: No config space access function found"
Date
From: Dexuan Cui <decui@microsoft.com>

[ Upstream commit 2f285f46240d67060061d153786740d4df53cd78 ]

A Generation-2 Linux VM on Hyper-V doesn't have the legacy PCI bus, and
users always see the scary warning, which is actually harmless.

Suppress it.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: KY Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: "devel@linuxdriverproject.org" <devel@linuxdriverproject.org>
Cc: Olaf Aepfle <olaf@aepfle.de>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Marcelo Cerri <marcelo.cerri@canonical.com>
Cc: Josh Poulson <jopoulso@microsoft.com>
Link: https://lkml.kernel.org/r/ <KU1P153MB0166D977DC930996C4BF538ABF1D0@KU1P153MB0166.APCP153.PROD.OUTLOOK.COM
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/hyperv/hv_init.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 3fb8551552862..8a9cff1f129dc 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -17,6 +17,7 @@
*
*/

+#include <linux/efi.h>
#include <linux/types.h>
#include <asm/apic.h>
#include <asm/desc.h>
@@ -257,6 +258,22 @@ static int hv_cpu_die(unsigned int cpu)
return 0;
}

+static int __init hv_pci_init(void)
+{
+ int gen2vm = efi_enabled(EFI_BOOT);
+
+ /*
+ * For Generation-2 VM, we exit from pci_arch_init() by returning 0.
+ * The purpose is to suppress the harmless warning:
+ * "PCI: Fatal: No config space access function found"
+ */
+ if (gen2vm)
+ return 0;
+
+ /* For Generation-1 VM, we'll proceed in pci_arch_init(). */
+ return 1;
+}
+
/*
* This function is to be invoked early in the boot sequence after the
* hypervisor has been detected.
@@ -333,6 +350,8 @@ void __init hyperv_init(void)

hv_apic_init();

+ x86_init.pci.arch_init = hv_pci_init;
+
/*
* Register Hyper-V specific clocksource.
*/
--
2.20.1
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