Re: [Xen-devel] [BUG] repeated live migration for VM failed

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 22/05/17 07:35, Hao, Xudong wrote:
> Bug detailed description:
> 
> ----------------
> 
> Create one RHEL7.3 HVM and do live migration continuously, while doing the 
> 200+ or 300+ times live-migration, tool stack report error and migration 
> failed.
> 
> 
> 
> Environment :
> 
> ----------------
> 
> HW: Skylake server
> 
> Xen: Xen 4.9.0 RC4
> 
> Dom0: Linux 4.11.0
> 
> 
> 
> Reproduce steps:
> 
> ----------------
> 
> 1.      Compile Xen 4.9 Rc4 and dom0 kernel 4.11.0, boot to dom0
> 
> 2.      Boot RHEL7.3 HVM guest
> 
> 3.      Migrate guest to localhost, sleep 10 seconds
> 
> 4.      Repeat doing the step3.
> 
> 
> 
> Current result:
> 
> ----------------
> 
> VM Migration fail.
> 
> 
> 
> Base error log:
> 
> ----------------
> 
> xl migrate 24hrs_lm_guest_2 localhost
> 
> root@localhost's password:
> 
> migration target: Ready to receive domain.
> 
> Saving to migration stream new xl format (info 0x3/0x0/1761)
> 
> Loading new save file <incoming migration stream> (new xl fmt info 
> 0x3/0x0/1761)
> 
> Savefile contains xl domain config in JSON format
> 
> Parsing config from <saved>
> 
> xc: info: Saving domain 273, type x86 HVM
> 
> xc: info: Found x86 HVM domain from Xen 4.9
> 
> xc: info: Restoring domain
> 
> xc: error: set HVM param 12 = 0x00000000feffe000 (85 = Interrupted system 
> call should ): Internal error
> 
> xc: error: Restore failed (85 = Interrupted system call should ): Internal 
> error

Interesting -- it appears that setting HVM_PARAM_IDENT_PT (#12) can fail
with -ERESTART.  But the comment for ERESTART makes it explicit that it
should be internal only -- it should cause a hypercall continuation (so
that the hypercall restarts automatically), rather than returning to the
guest.

But the hypercall continuation code seems to have disappeared from
do_hvm_op() at some point?

/me digs a bit more...

 -George


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