From: Dexuan Cui <de...@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 <de...@microsoft.com>
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Reviewed-by: Michael Kelley <mikel...@microsoft.com>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: KY Srinivasan <k...@microsoft.com>
Cc: Haiyang Zhang <haiya...@microsoft.com>
Cc: Stephen Hemminger <sthem...@microsoft.com>
Cc: "de...@linuxdriverproject.org" <de...@linuxdriverproject.org>
Cc: Olaf Aepfle <o...@aepfle.de>
Cc: Andy Whitcroft <a...@canonical.com>
Cc: Jason Wang <jasow...@redhat.com>
Cc: Vitaly Kuznetsov <vkuzn...@redhat.com>
Cc: Marcelo Cerri <marcelo.ce...@canonical.com>
Cc: Josh Poulson <jopou...@microsoft.com>
Link: https://lkml.kernel.org/r/ 
<ku1p153mb0166d977dc930996c4bf538abf...@ku1p153mb0166.apcp153.prod.outlook.com
Signed-off-by: Sasha Levin <sas...@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 2e9d58cc371e6..2653b7b25d176 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/hypervisor.h>
 #include <asm/hyperv.h>
@@ -101,6 +102,22 @@ static int hv_cpu_init(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.
@@ -154,6 +171,8 @@ void hyperv_init(void)
 
        hyper_alloc_mmu();
 
+       x86_init.pci.arch_init = hv_pci_init;
+
        /*
         * Register Hyper-V specific clocksource.
         */
-- 
2.20.1



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