Re: [Xen-devel] [PATCH v10 07/11] xen: delay allocation of grant table sub structures

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 25/09/17 11:00, Juergen Gross wrote:
> Delay the allocation of the grant table sub structures in order to
> allow modifying parameters needed for sizing of these structures at a
> per domain basis. Allocate the structures and the table frames only
> from grant_table_init().
>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>

I've just rebased my hypervisor and booting an HVM guest is going splat
thusly:

(XEN) Assertion 'gt->active' failed at grant_table.c:1672
(XEN) ----[ Xen-4.10-unstable  x86_64  debug=y   Not tainted ]----
(XEN) CPU:    0
(XEN) RIP:    e008:[<ffff82d08020d92c>] 
grant_table.c#gnttab_grow_table+0x26/0x383
(XEN) RFLAGS: 0000000000010246   CONTEXT: hypervisor (d0v1)
(XEN) rax: 00000000ffffffea   rbx: ffff83082b783ec0   rcx: 0000000000000010
(XEN) rdx: 0000000000000020   rsi: 0000000000000001   rdi: ffff83082b782000
(XEN) rbp: ffff8300abe4fca8   rsp: ffff8300abe4fc58   r8:  0000000000000000
(XEN) r9:  deadbeefdeadf00d   r10: 0000000000000000   r11: 0000000000000282
(XEN) r12: ffff8300abe4fd10   r13: 0000000000000000   r14: ffff83082b782000
(XEN) r15: 00007fee507d3004   cr0: 0000000080050033   cr4: 00000000001526e0
(XEN) cr3: 000000083412c000   cr2: ffff880086270140
(XEN) ds: 0000   es: 0000   fs: 0000   gs: 0000   ss: e010   cs: e008
(XEN) Xen code around <ffff82d08020d92c> 
(grant_table.c#gnttab_grow_table+0x26/0x383):
(XEN)  00 48 83 7b 40 00 75 02 <0f> 0b 8b 75 c8 83 fe 03 b8 04 00 00 00 0f 47 c6
(XEN) Xen stack trace from rsp=ffff8300abe4fc58:
(XEN)    0000000800000001 0000000000000000 ffff83082b782000 ffff82d000000001
(XEN)    ffff8300abe4fca8 ffff83082b783ec0 ffff8300abe4fd10 0000000000000000
(XEN)    ffff83082b782000 00007fee507d3004 ffff8300abe4fcd8 ffff82d080216ae5
(XEN)    0000000000000001 ffff83082b782000 0000000000000000 00000000000ff000
(XEN)    ffff8300abe4fd48 ffff82d080282c31 0000000000000000 8086000000008086
(XEN)    0000000000000003 ffff880086270140 ffffffff81181268 ffffffffffffffff
(XEN)    0000000000000000 0000000000000001 0000000000000000 0000000000000000
(XEN)    ffff83082b782000 00007fee507d3004 ffff8300abe4fe68 ffff82d08021ecd3
(XEN)    ffff8300abf7d000 ffff8308373eb000 0000000000000000 ffff8300abf7d000
(XEN)    ffff8300abe4fd98 ffff82d08028a70f 00000000ffffffff ffff8308373e0000
(XEN)    ffff8300abe4fe68 ffff82d08028bca1 000000000000e033 0000000000010246
(XEN)    0000000100000001 0000000000000000 00000000000ff000 ffff82d08035285e
(XEN)    ffff82d08057aa88 ffff8300abe4ffff ffff8300abe4fe68 ffff82d080357a95
(XEN)    ffff880087e2aa68 00000000000fefff 0000000000000246 00007fee4f7f2537
(XEN)    0000000000000100 00007fee4f7f2537 0000000000000033 0000000000000246
(XEN)    00007ffdef7c6fa8 ffff8300abe4ff18 ffff8300abf7d000 000000000000000c
(XEN)    ffff82d08021db9d deadbeefdeadf00d ffff8300abe4ff08 ffff82d0803574fe
(XEN)    0200008700000001 0000000000000007 00007fee507d3004 deadbeefdeadf00d
(XEN)    deadbeefdeadf00d deadbeefdeadf00d ffff8300abf7d000 ffff880086270140
(XEN)    ffff8300abe4ff08 ffff82d0802a03f5 ffff8300abe4fef8 ffff82d080237abe
(XEN) Xen call trace:
(XEN)    [<ffff82d08020d92c>] grant_table.c#gnttab_grow_table+0x26/0x383
(XEN)    [<ffff82d080216ae5>] gnttab_map_frame+0x11a/0x1e6
(XEN)    [<ffff82d080282c31>] xenmem_add_to_physmap_one+0xda/0x40c
(XEN)    [<ffff82d08021ecd3>] do_memory_op+0x1136/0x2573
(XEN)    [<ffff82d0803574fe>] pv_hypercall+0x1ef/0x42d
(XEN)    [<ffff82d08035bfd6>] x86_64/entry.S#test_all_events+0/0x30
(XEN) 
(XEN) 
(XEN) ****************************************
(XEN) Panic on CPU 0:
(XEN) Assertion 'gt->active' failed at grant_table.c:1672
(XEN) ****************************************

I've not taken a new toolstack (as I'm unable to atm), but it looks like
the correctness of hypervisor behaviour might now depend on toolstack
behaviour, which is distinctly suboptimal.

~Andrew

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