pvh: disable pse feature for now

pvh: disable pse feature for now

[Mukesh Rathor]

Konrad,

Following will turn off PSE in linux until we can get to it. It's better
to turn it off here than in xen, so if BSD gets there sooner, they are not 
dependent on us.

thanks
Mukesh

[V0 PATCH] pvh: Disable PSE feature for now

[Mukesh Rathor]

Until now, xen did not expose PSE to pvh guest, but a patch was submitted
to xen list to enable bunch of features for a pvh guest. PSE has not been
looked into for PVH, so until we can do that and test it to make sure it
works, disable the feature to avoid flood of bugs.

Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
---
 arch/x86/xen/enlighten.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index a4d7b64..4e952046 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1497,6 +1497,11 @@ static void __init xen_pvh_early_guest_init(void)
 	xen_have_vector_callback = 1;
 	xen_pvh_set_cr_flags(0);
 
+        /* pvh guests are not quite ready for large pages yet */
+        setup_clear_cpu_cap(X86_FEATURE_PSE);
+        setup_clear_cpu_cap(X86_FEATURE_PSE36);
+
+
 #ifdef CONFIG_X86_32
 	BUG(); /* PVH: Implement proper support. */
 #endif
-- 
1.7.2.3

Re: [V0 PATCH] pvh: Disable PSE feature for now

[Konrad Rzeszutek Wilk]

On Mon, Jan 27, 2014 at 06:18:39PM -0800, Mukesh Rathor wrote:
> Until now, xen did not expose PSE to pvh guest, but a patch was submitted
> to xen list to enable bunch of features for a pvh guest. PSE has not been

Which 'patch'?

> looked into for PVH, so until we can do that and test it to make sure it
> works, disable the feature to avoid flood of bugs.

I think we want a flood of bugs, no?
> 
> Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
> ---
>  arch/x86/xen/enlighten.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index a4d7b64..4e952046 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1497,6 +1497,11 @@ static void __init xen_pvh_early_guest_init(void)
>  	xen_have_vector_callback = 1;
>  	xen_pvh_set_cr_flags(0);
>  
> +        /* pvh guests are not quite ready for large pages yet */
> +        setup_clear_cpu_cap(X86_FEATURE_PSE);
> +        setup_clear_cpu_cap(X86_FEATURE_PSE36);
> +
> +
>  #ifdef CONFIG_X86_32
>  	BUG(); /* PVH: Implement proper support. */
>  #endif
> -- 
> 1.7.2.3
> 

Re: [Xen-devel] [V0 PATCH] pvh: Disable PSE feature for now

[Jan Beulich]

>>> On 28.01.14 at 03:18, Mukesh Rathor <mukesh.rathor@oracle.com> wrote:
> Until now, xen did not expose PSE to pvh guest, but a patch was submitted
> to xen list to enable bunch of features for a pvh guest. PSE has not been
> looked into for PVH, so until we can do that and test it to make sure it
> works, disable the feature to avoid flood of bugs.
> 
> Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
> ---
>  arch/x86/xen/enlighten.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index a4d7b64..4e952046 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1497,6 +1497,11 @@ static void __init xen_pvh_early_guest_init(void)
>  	xen_have_vector_callback = 1;
>  	xen_pvh_set_cr_flags(0);
>  
> +        /* pvh guests are not quite ready for large pages yet */
> +        setup_clear_cpu_cap(X86_FEATURE_PSE);
> +        setup_clear_cpu_cap(X86_FEATURE_PSE36);

And why would you not want to also turn of 1Gb pages then?

Jan

Re: [V0 PATCH] pvh: Disable PSE feature for now

[Mukesh Rathor]

On Mon, 27 Jan 2014 22:46:34 -0500
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote:

> On Mon, Jan 27, 2014 at 06:18:39PM -0800, Mukesh Rathor wrote:
> > Until now, xen did not expose PSE to pvh guest, but a patch was
> > submitted to xen list to enable bunch of features for a pvh guest.
> > PSE has not been
> 
> Which 'patch'?
> 
> > looked into for PVH, so until we can do that and test it to make
> > sure it works, disable the feature to avoid flood of bugs.
> 
> I think we want a flood of bugs, no?

Ok, but lets document (via this email :)), that they are not tested.

thanks
Mukesh

Re: [Xen-devel] [V0 PATCH] pvh: Disable PSE feature for now

[Mukesh Rathor]

On Tue, 28 Jan 2014 10:39:23 +0000
"Jan Beulich" <JBeulich@suse.com> wrote:

> >>> On 28.01.14 at 03:18, Mukesh Rathor <mukesh.rathor@oracle.com>
> >>> wrote:
> > Until now, xen did not expose PSE to pvh guest, but a patch was
> > submitted to xen list to enable bunch of features for a pvh guest.
> > PSE has not been looked into for PVH, so until we can do that and
> > test it to make sure it works, disable the feature to avoid flood
> > of bugs.
> > 
> > Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
> > ---
> >  arch/x86/xen/enlighten.c |    5 +++++
> >  1 files changed, 5 insertions(+), 0 deletions(-)
> > 
> > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> > index a4d7b64..4e952046 100644
> > --- a/arch/x86/xen/enlighten.c
> > +++ b/arch/x86/xen/enlighten.c
> > @@ -1497,6 +1497,11 @@ static void __init
> > xen_pvh_early_guest_init(void) xen_have_vector_callback = 1;
> >  	xen_pvh_set_cr_flags(0);
> >  
> > +        /* pvh guests are not quite ready for large pages yet */
> > +        setup_clear_cpu_cap(X86_FEATURE_PSE);
> > +        setup_clear_cpu_cap(X86_FEATURE_PSE36);
> 
> And why would you not want to also turn of 1Gb pages then?

Right, that should be turned off too, but Konrad thinks we should
leave them on in linux and deal with issues as they come. I've not
tested them, or looked/thought about them, so had thought would be 
better to turn them on after I/someone gets to test them.

thanks
Mukesh