Re: [PATCH] xen: fix pv domain on amd in 4.9 stable branch

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, May 29, 2018 at 03:11:36PM +0200, Juergen Gross wrote:
> 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.

What is the prerequsite patch's git id in Linus's tree?

> Fix that by adding the prerequisite setting of X86_FEATURE_XENPV to the
> Xen pv early boot path.
> 
> Cc: David Woodhouse <dwmw@amazon.co.uk>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
>  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

I'd prefer to take whatever is in Linus's tree if at all possible.

thanks,

greg k-h