RE: [Xen-devel] AMD crash on restore. bug in MTRR restore.4.0.2-rc2-pre

[Wei Huang <wei.huang2@xxxxxxx>]

Hi James,

Could you try the attached patch? The issue is because we don't
intercept SYSENTER_xx MSRs under 32bit mode (guest mode). As a result,
hvm_svm.guest_sysenter_xx contain invalid values. So save/restore will
eventually fail by using these values. This patch solves the problem.

If it works, please let me know and I will submit a formal one.

Best,
-Wei

On Wed, 2011-01-26 at 21:49 -0600, James Harper wrote:
> By saving the sysenter msrs in my PV drivers before the suspend
> hypercall and restoring them after, save/restore now works fine.
> 
> Does nobody else see a save/restore failure on AMD as a blocker to
> 4.0.2? It it something particular to my exact AMD CPU and OS (Windows
> 2008 x32)?
> 
> James
> 
> > -----Original Message-----
> > From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-
> > bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of James Harper
> > Sent: Thursday, 27 January 2011 13:32
> > To: xen-devel@xxxxxxxxxxxxxxxxxxx
> > Cc: Tim Deegan
> > Subject: RE: [Xen-devel] AMD crash on restore. bug in MTRR
> restore.4.0.2-rc2-
> > pre
> > 
> > Additionally, WinDbg tells me that MSR's 175, and 176 are wiped out by
> > save/restore:
> > 
> > immediately before suspend
> > kd> rdmsr 174
> > msr[174] = 00000000`00000008
> > kd> rdmsr 175
> > msr[175] = 00000000`8039e000
> > kd> rdmsr 176
> > msr[176] = 00000000`816a4950
> > 
> > immediately after restore
> > kd> rdmsr 174
> > msr[174] = 00000000`00000000
> > kd> rdmsr 175
> > msr[175] = 00000000`00000000
> > kd> rdmsr 176
> > msr[176] = 00000000`00000000
> > 
> > although you're never too sure with WinDbg...
> > 
> > James
> > 
> > > -----Original Message-----
> > > From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-
> > > bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of James Harper
> > > Sent: Wednesday, 26 January 2011 17:19
> > > To: xen-devel@xxxxxxxxxxxxxxxxxxx
> > > Cc: Tim Deegan
> > > Subject: [Xen-devel] AMD crash on restore. bug in MTRR restore.
> > 4.0.2-rc2-pre
> > >
> > > The mtrr save code on my AMD system reads the first MTRR as
> > > 0x00000000f0000000,0x000000fff8000800. When it tries to restore in
> > > mtrr_var_range_msr_set, 0x000000fff8000800 is rejected as invalid
> and
> > > not restored.
> > >
> > > Commenting out the check against the mask, as well as Tim's patch to
> > fix
> > > the segment registers makes the output of xen-hvmctx match before
> the
> > > save and after the restore.
> > >
> > > Windows still crashes on restore though so I don't know if this has
> > > anything to do with it.
> > >
> > > James
> > >
> > > _______________________________________________
> > > Xen-devel mailing list
> > > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > > http://lists.xensource.com/xen-devel
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
>

Attachment: amd_fix_sysenter_msr.txt
Description: amd_fix_sysenter_msr.txt

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