Re: [Xen-devel] [Patch 0/6] Xen vMCE implement

["Liu, Jinsong" <jinsong.liu@xxxxxxxxx>]

Comments?

Thanks,
Jinsong

Liu, Jinsong wrote:
> Hi,
> 
> These patches are Xen vMCE implement, among them
> ===================
> Patch 1: This patch is a middle-work patch, prepare for future new
> vMCE model. It remove mci_ctl array, and keep MCi_CTL all 1's. 
> Patch 2: This patch is a middle-work patch, prepare for future new
> vMCE model. It remove mcg_ctl, disable MCG_CTL_P, and set bank number
> to 2.  
> 
> Patch 3: vMCE emulation
> This patch provides virtual MCE support to guest. It emulates a
> simple and clean MCE MSRs interface to guest by faking caps to guest
> if needed and masking caps if unnecessary:  
> 1. Providing a well-defined MCG_CAP to guest, filter out un-necessary
> caps and provide only guest needed caps; 
> 2. Disabling MCG_CTL to avoid model specific;
> 3. Sticking all 1's to MCi_CTL to guest to avoid model specific;
> 4. Enabling CMCI cap but never really inject to guest to prevent
> polling periodically; 
> 5. Masking MSCOD field of MCi_STATUS to avoid model specific;
> 6. Keeping natural semantics by per-vcpu instead of per-domain
> variables; 
> 7. Using bank1 and reserving bank0 to work around 'bank0 quirk' of
> some very old processors; 
> 8. Cleaning some vMCE# injection logic which shared by Intel and AMD
> but useless under new vMCE implement; 
> 9. Keeping compatilbe w/ old xen version which has been backported to
> SLES11 SP2, so that old vMCE would not blocked when migrate to new
> vMCE;  
> 
> Patch 4: vMCE injection
> In our test for win8 guest mce, we find a bug that no matter what
> SRAO/SRAR error xen inject to win8 guest, it always reboot. The root
> cause is, current Xen vMCE logic inject vMCE# only to vcpu0, this is
> not correct for Intel MCE (Under Intel arch, h/w generate MCE# to all
> CPUs). This patch fix vMCE injection bug, injecting vMCE# to all
> vcpus.    
> 
> Patch 5: vMCE save and restore
> This patch provide vMCE save/restore when migration.
> 1. MCG_CAP is well-defined. However, considering future cap
> extension, we keep save/restore logic that Jan implement at c/s
> 24887;  
> 2. MCi_CTL2 initialized by guestos when booting, so need save/restore
> otherwise guest would surprise; 
> 3. Other MSRs do not need save/restore since they are either
> error-related and pointless to save/restore, or, unified among all
> vMCE platform;  
> 
> Patch 6: Cleanup guest vMCE check
> This patch simplify vMCE logic by removing guest vMCE check, since
> hypervisor should be agnostic to guest. 
> With guest vMCE check, hypervisor would actively kill guest when
> guest vMCE not ready. Without guest vMCE check, hypervisor would
> always inject vMCE to guest: if guest ready it would happily handle
> it, and if guest not ready, it automatically kill itself.
> ====================   
> 
> These patches have been tested w/ Linux and Windows 8 guestos, and
> worked fine. 
> 
> Considering Intel and AMD common vMCE interface to guest, these
> patches are mainly put in vmce.c (except mci_ctl2 in intel specific
> code since this MSRs are supported by Intel only). AMD code could
> update them according to AMD's specific requirement.   
> 
> These patches didn't handle the corner case 'MCE occur when live
> migration'. We have draftly done the patch for the corner case but
> meet issue now (seems caused from Xen live migration logic itself, we
> are debugging it now, and would present soon when it fixed).   
> 
> Thanks,
> Jinsong
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxx
> http://lists.xen.org/xen-devel


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