[PATCH AUTOSEL 4.19 156/191] x86/hyperv: Suppress "PCI: Fatal: No config space access function found"

[Sasha Levin]

From: Dexuan Cui <decui@xxxxxxxxxxxxx>

[ 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@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: KY Srinivasan <kys@xxxxxxxxxxxxx>
Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
Cc: "devel@xxxxxxxxxxxxxxxxxxxxxx" <devel@xxxxxxxxxxxxxxxxxxxxxx>
Cc: Olaf Aepfle <olaf@xxxxxxxxx>
Cc: Andy Whitcroft <apw@xxxxxxxxxxxxx>
Cc: Jason Wang <jasowang@xxxxxxxxxx>
Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Cc: Marcelo Cerri <marcelo.cerri@xxxxxxxxxxxxx>
Cc: Josh Poulson <jopoulso@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/ <KU1P153MB0166D977DC930996C4BF538ABF1D0@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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