Xen-4.4-rc2 - Some Nested Virt testing

[Andrew Cooper <andrew.cooper3@citrix.com>]

Hello,

I have been giving nested virt a try, and have my first bug to report. 
This is still ongoing, and is by no means complete yet.

Setup:
Each reference to XenServer is a trunk XenServer based on 4.4-rc2

Single Intel Haswell SDP (Grantley platform):
Native hypervisor: XenServer

Two L1 guests:
  XenServer (running with EPT)
  XenServer (running with shadow)


When attempting to create an L2 EPT HVM domain under an L1 shadow
domain, the L1 shadow domain is killed with:

(XEN) <vm_launch_fail> error code 7
(XEN) domain_crash_sync called from vmcs.c:1293
(XEN) Domain 16 (vcpu#3) crashed on cpu#2:
(XEN) ----[ Xen-4.4.0-xs82349-d  x86_64  debug=y  Not tainted ]----
(XEN) CPU:    2
(XEN) RIP:    0000:[<0000000000000000>]
(XEN) RFLAGS: 0000000000000002   CONTEXT: hvm guest
(XEN) rax: 0000000000000000   rbx: ffff83043cad8000   rcx: ffff83043cadff80
(XEN) rdx: ffff82d0801d6ea0   rsi: 0000000000000000   rdi: ffff82d0801e2e8c
(XEN) rbp: ffff82d080105680   rsp: 0000000000000000   r8:  ffff830064100000
(XEN) r9:  ffff82d0801056ee   r10: ffff83043cadff70   r11: 0000000000000000
(XEN) r12: ffff83043cadff50   r13: ffff830441e42000   r14: ffff830064100000
(XEN) r15: ffff82d080189425   cr0: 0000000000000039   cr4: 0000000000002050
(XEN) cr3: 0000000000000000   cr2: 0000000000000000
(XEN) ds: 0000   es: 0000   fs: 0000   gs: 0000   ss: 0000   cs: 0000


I am continuing experiments with different VMs under each L1 hypervisor,
to see what else breaks.

~Andrew