[Xen-devel] [PATCH] xen: fix pv domain on amd in 4.9 stable branch

[Juergen Gross <jgross@xxxxxxxx>]

Commit 944e0fc51a89c9827b98813d65dc083274777c7f ("x86/amd: don't set
X86_BUG_SYSRET_SS_ATTRS when running under Xen") breaks Xen pv-domains
on AMD processors, as a prerequisite patch from upstream wasn't added
to 4.9.

Fix that by adding the prerequisite setting of X86_FEATURE_XENPV to the
Xen pv early boot path.

Cc: David Woodhouse <dwmw@xxxxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 arch/x86/xen/enlighten.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 081437b5f381..674656cdb68c 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1632,6 +1632,9 @@ asmlinkage __visible void __init xen_start_kernel(void)
        xen_init_irq_ops();
        xen_init_cpuid_mask();
 
+       /* Needed for init_amd(). */
+       setup_force_cpu_cap(X86_FEATURE_XENPV);
+
 #ifdef CONFIG_X86_LOCAL_APIC
        /*
         * set up the basic apic ops.
-- 
2.13.6


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