[Crash-utility] [PATCH] vmware_vmss: read vCPUs regs and show them in 'bt'

[Dave Anderson]

----- Original Message -----
> On Wed, Mar 21, 2018 at 10:44:47AM -0400, Dave Anderson wrote:
> > 
> > 
> > ----- Original Message -----
> > > VMSS dump files contain the state of each vCPU at the time of suspending
> > > the VM. This change enables 'crash' to read some relevant registers from
> > > each vCPU state and display them in 'bt'.
> > 
> > That's very helpful.  I'm not sure why VMware never did anything like that
> > in the original patch.
> > 
> > And now that there finally is a VMSS_DUMPFILE() indicator, it would be helpful
> > to at least display *something* w/respect to the dumpfile contents as viewed from
> > "help -D".   If you bring up the session with "crash -d1" you will see a bunch
> > of stuff from the dumpfile, although I'm not sure whether all of it would be
> > useful during runtime.  But if nothing else, at least indicate what kind of
> > dumpfile it is, and anything else that might be useful.
> >  
> > Also, I just noticed that original patch from VMware does not display the
> > VMWARE_VMSS bit in pc->flag as show by "help -p".  Can you add that too?
> 
> I didn't pay any attention to the "help" command. I'm going to implement
> the VMWARE_VMSS bit in pc->flag, and also the "help -r" output, which
> seems quite straightforward having all the registers already properly
> placed in vmssregs64.

Nice.  Note that the VMWARE_VMSS bit has always been set in pc->flags, but
it was never displayed in dump_program_context().

> 
> As for "help -D", I think we could implement a function that iterates
> through groups and tags present in the VMSS, printing names, sizes and
> values (for non-block tags). Basically, it'd be the same thing that
> "vmware_vmss_init" does, but unconditionally printing the info without
> touching anything else. Does this makes sense to you?

Yep, whatever you'd like to see.

> 
> > > calculation for VMSS dump files.
> > 
> > Will that require the KASLR helper patch as a prerequisite?
> 
> Yes, otherwise we'd need to duplicate "calc_kaslr_offset" and all the
> related functions.

OK.  Hopefully Takao and Daisuke get back to us soon.

Thanks,
  Dave