Xen devel - Aug 2013 - x86/AMD: Nested VM stuck when probing ATA ports

Hi All,

I  have run  into another issue withnested VM on AMD systemwhere theL2 Linux
guest stuck
waiting while booting  inthe async_synchronize_full() of init/main.c.

static int __ref kernel_init(void *unused)
{
         kernel_init_freeable();
         /* need to finish all async __init code before freeing the memory */
          async_synchronize_full();    <-- INHERE
         free_initmem();
         mark_rodata_ro();
         system_state = SYSTEM_RUNNING;

When Iboot the L2 Linux guest with "initcall_debug"opion and look
through  the
boot debugmessage, I notice thatthe initcall to "async_port_probe()"
neverreturn.
This function isasynchrounous  scheduled as part of ATA host initialization
(see driver/ata/libata-core.c:ata_host_register()).

	/* perform each probe asynchronously */
	for (i = 0; i < host->n_ports; i++) {
		struct ata_port *ap = host->ports[i];
		async_schedule(async_port_probe, ap);
	}

Here,theasync_port_probeis schedule twice since there are two ports, and none
has returned.
When tracing this function call, bothcalls  stuckin the

     async_port_probe()-> ata_port_probe()->ata_port_wait_eh()

I have also attached the L2guest serial consoleoutput.

Also,when run xentrace on L0,I  can see  the  trace going thougha series of
VMENTRY/EXIT
for handling timer interrupt for L2.  So, I don''t think theL2
guestcrashes.

At  this point, I am not sure why the probe fail here and might need help
further debuggingthe issue.

Thank you,

Suravee




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