x86 / cpupool: clear the proper cpu_valid bit on pCPU teardown
In fact, when a pCPU goes down, we want to clear its
bit in the correct cpupool's valid mask, rather than
always in cpupool0's one.
Before this commit, all the pCPUs in the non-default
pool(s) will be considered immediately valid, during
system resume, even the one that have not been brought
up yet. As a result, the (Credit1) scheduler will attempt
to run its load balancing logic on them, causing the
following Oops:
# xl cpupool-cpu-remove Pool-0 8-15
# xl cpupool-create name=\"Pool-1\"
# xl cpupool-cpu-add Pool-1 8-15
--> suspend
--> resume
(XEN) ----[ Xen-4.6-unstable x86_64 debug=y Tainted: C ]----
(XEN) CPU: 8
(XEN) RIP: e008:[<
ffff82d080123078>] csched_schedule+0x4be/0xb97
(XEN) RFLAGS:
0000000000010087 CONTEXT: hypervisor
(XEN) rax:
80007d2f7fccb780 rbx:
0000000000000009 rcx:
0000000000000000
(XEN) rdx:
ffff82d08031ed40 rsi:
ffff82d080334980 rdi:
0000000000000000
(XEN) rbp:
ffff83010000fe20 rsp:
ffff83010000fd40 r8:
0000000000000004
(XEN) r9:
0000ffff0000ffff r10:
00ff00ff00ff00ff r11:
0f0f0f0f0f0f0f0f
(XEN) r12:
ffff8303191ea870 r13:
ffff8303226aadf0 r14:
0000000000000009
(XEN) r15:
0000000000000008 cr0:
000000008005003b cr4:
00000000000026f0
(XEN) cr3:
00000000dba9d000 cr2:
0000000000000000
(XEN) ds: 0000 es: 0000 fs: 0000 gs: 0000 ss: 0000 cs: e008
(XEN) ... ... ...
(XEN) Xen call trace:
(XEN) [<
ffff82d080123078>] csched_schedule+0x4be/0xb97
(XEN) [<
ffff82d08012c732>] schedule+0x12a/0x63c
(XEN) [<
ffff82d08012f8c8>] __do_softirq+0x82/0x8d
(XEN) [<
ffff82d08012f920>] do_softirq+0x13/0x15
(XEN) [<
ffff82d080164791>] idle_loop+0x5b/0x6b
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 8:
(XEN) GENERAL PROTECTION FAULT
(XEN) [error_code=0000]
(XEN) ****************************************
The reason why the error is a #GP fault is that, without
this commit, we try to access the per-cpu area of a not
yet allocated and initialized pCPU.
In fact, %rax, which is what is used as pointer, is
80007d2f7fccb780, and we also have this:
#define INVALID_PERCPU_AREA (0x8000000000000000L - (long)__per_cpu_start)
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Juergen Gross <jgross@suse.com>
projects / xen.git / commit