linux-kernel - [PATCH 4.19 206/361] xen/pvh: dont try to unplug emulated devices

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Date:   Sun, 11 Nov 2018 14:19:13 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>
Subject: [PATCH 4.19 206/361] xen/pvh: dont try to unplug emulated devices

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Juergen Gross <jgross@...e.com>

commit e6111161c0a02d58919d776eec94b313bb57911f upstream.

A Xen PVH guest has no associated qemu device model, so trying to
unplug any emulated devices is making no sense at all.

Bail out early from xen_unplug_emulated_devices() when running as PVH
guest. This will avoid issuing the boot message:

[    0.000000] Xen Platform PCI: unrecognised magic value

Cc: <stable@...r.kernel.org> # 4.11
Signed-off-by: Juergen Gross <jgross@...e.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/xen/platform-pci-unplug.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/arch/x86/xen/platform-pci-unplug.c
+++ b/arch/x86/xen/platform-pci-unplug.c
@@ -146,6 +146,10 @@ void xen_unplug_emulated_devices(void)
 {
 	int r;
 
+	/* PVH guests don't have emulated devices. */
+	if (xen_pvh_domain())
+		return;
+
 	/* user explicitly requested no unplug */
 	if (xen_emul_unplug & XEN_UNPLUG_NEVER)
 		return;