Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1218627

Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup

Show all headers | View raw

On Fri, 2015-09-04 at 01:54 +0200, Luis R. Rodriguez wrote:
> On Thu, Sep 03, 2015 at 05:21:14PM -0600, Toshi Kani wrote:
> > On Fri, 2015-09-04 at 00:45 +0200, Luis R. Rodriguez wrote:
> > > On Thu, Sep 03, 2015 at 04:25:31PM -0600, Toshi Kani wrote:
 :
> > > > On Xen,
> > > 
> > > When Xen is used a platform firmware may still set up MTRR, even if the
> > > hypervisor doesn't set up MTRR right ? So same issue and question here.
> > 
> > Right, I meant to say Xen guests.
> 
> Ah but its import complicated than that.
> 
> > In case of the Xen hypervisor,
> > mtrr_type_lookup() returns a valid type as it runs on a platform.
> 
> I am not sure if this happens today, I know MTRR is simply disabled by
> the Xen Hypervisor on the CPU explicitly, it disable it so guests reading
> the MTRR capabilities sees it as disabled when queried.

Oh, I would not let the hypervisor to disable MTRRs...

> Then since the Xen Linux guests cannot speak MTRR through the hypervisor
> (for instance Xen guests cannot ask Xen hypervisor to mtrr_type_lookup() for
> it) if PCI passthrough is used it could mean a guest might set up / use
> incorrect info as well.
> 
> If I undestand this correctly then I think we're in a pickle with Xen unless
> we add hypervisor support and hypercall support for mtrr_type_lookup().

I was under assumption that MTRRs are emulated and disabled on guests.  Isn't
guest physical address virtualized?  I know other proprietary VMMs on IA64,
but know nothing about Xen...  So, please disregard my comments to Xen. :-)

Thanks,
-Toshi
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup Stuart Hayes <stuart.w.hayes@gmail.com> - 2015-08-31 18:10 +0200
  Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup "Luis R. Rodriguez" <mcgrof@suse.com> - 2015-09-03 04:50 +0200
    Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup Prarit Bhargava <prarit@redhat.com> - 2015-09-03 14:20 +0200
      Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup "Luis R. Rodriguez" <mcgrof@suse.com> - 2015-09-03 20:00 +0200
        Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup Prarit Bhargava <prarit@redhat.com> - 2015-09-03 20:20 +0200
          Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup "Luis R. Rodriguez" <mcgrof@suse.com> - 2015-09-03 20:50 +0200
            Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup Toshi Kani <toshi.kani@hpe.com> - 2015-09-03 21:30 +0200
              Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup "Luis R. Rodriguez" <mcgrof@suse.com> - 2015-09-03 22:00 +0200
                Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup Toshi Kani <toshi.kani@hpe.com> - 2015-09-03 23:40 +0200
                Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup "Luis R. Rodriguez" <mcgrof@suse.com> - 2015-09-04 00:10 +0200
                Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup Toshi Kani <toshi.kani@hpe.com> - 2015-09-04 00:30 +0200
                Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup "Luis R. Rodriguez" <mcgrof@suse.com> - 2015-09-04 00:50 +0200
                Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup Toshi Kani <toshi.kani@hpe.com> - 2015-09-04 01:30 +0200
                Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup "Luis R. Rodriguez" <mcgrof@suse.com> - 2015-09-04 02:00 +0200
                Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup Toshi Kani <toshi.kani@hpe.com> - 2015-09-04 03:00 +0200
                Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup "Luis R. Rodriguez" <mcgrof@suse.com> - 2015-09-04 03:50 +0200
                Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup Toshi Kani <toshi.kani@hpe.com> - 2015-09-04 17:00 +0200
                Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup "Jan Beulich" <JBeulich@suse.com> - 2015-09-04 09:00 +0200

csiph-web