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

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

[Juergen Gross]

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@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

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

[Greg KH]

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

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

[Juergen Gross]

On 30/05/18 10:33, Greg KH wrote:
> 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?

Commit 0808e80cb760de2733c0527d2090ed2205a1eef8. It won't apply,
backporting is rather easy, though.

I thought this was a patch in the middle of a larger series, but
obviously I misremembered. It was the first patch of that series.

I'll send a series in case you don't object:

- revert of stable-4.9 944e0fc51a89c9827b98813d65dc083274777c7f
- backport of 0808e80cb760de2733c0527d2090ed2205a1eef8
- new backport of def9331a12977770cc6132d79f8e6565871e8e38


Juergen

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

[Greg KH]

On Wed, May 30, 2018 at 11:33:22AM +0200, Juergen Gross wrote:
> On 30/05/18 10:33, Greg KH wrote:
> > 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?
> 
> Commit 0808e80cb760de2733c0527d2090ed2205a1eef8. It won't apply,
> backporting is rather easy, though.
> 
> I thought this was a patch in the middle of a larger series, but
> obviously I misremembered. It was the first patch of that series.
> 
> I'll send a series in case you don't object:
> 
> - revert of stable-4.9 944e0fc51a89c9827b98813d65dc083274777c7f
> - backport of 0808e80cb760de2733c0527d2090ed2205a1eef8
> - new backport of def9331a12977770cc6132d79f8e6565871e8e38

That would be great, I'll gladly take that, thanks.

greg k-h