x86/hyperv: Suppress "PCI: Fatal: No config space access function found"

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/

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 20c876c..7abb09e 100644 (file)
--- 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>
@@ -253,6 +254,22 @@ 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.
@@ -329,6 +346,8 @@ void __init hyperv_init(void)
 
        hv_apic_init();
 
+       x86_init.pci.arch_init = hv_pci_init;
+
        /*
         * Register Hyper-V specific clocksource.
         */