[PATCH v4 5/5] xen: Add 'xen_nopv' parameter back for backward compatibility

[Zhenzhong Duan]

Map 'xen_nopv' to 'nopv' and mark 'xen_nopv' obsolete in
kernel-parameters.txt

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
---
 Documentation/admin-guide/kernel-parameters.txt | 6 ++++++
 arch/x86/xen/enlighten_hvm.c                    | 7 +++++++
 2 files changed, 13 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index d5c3dcc..34eb323 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5264,6 +5264,12 @@
 			improve timer resolution at the expense of processing
 			more timer interrupts.
 
+	xen_nopv	[X86]
+			Disables the PV optimizations forcing the HVM guest to
+			run as generic HVM guest with no PV drivers.
+			This option is obsoleted by the "nopv" option, which
+			has equivalent effect for XEN platform.
+
 	nopv=		[X86,XEN,KVM,HYPER_V,VMWARE]
 			Disables the PV optimizations forcing the guest to run
 			as generic guest with no PV drivers. Currently support
diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index 340dff8..5cdd608 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -211,6 +211,13 @@ static void __init xen_hvm_guest_init(void)
 #endif
 }
 
+static __init int xen_parse_nopv(char *arg)
+{
+	nopv = true;
+	return 0;
+}
+early_param("xen_nopv", xen_parse_nopv);
+
 bool __init xen_hvm_need_lapic(void)
 {
 	if (xen_pv_domain())
-- 
1.8.3.1