Re: [Xen-devel] [PATCH v7 0/9] xen/x86: various XPTI speedups

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 12/04/18 19:09, Juergen Gross wrote:
> This patch series aims at reducing the overhead of the XPTI Meltdown
> mitigation.

Sadly, there are still problems. 

(XEN) [   13.486805] Dom0 has maximum 2 VCPUs
(XEN) [   13.486824] ----[ Xen-4.11.0-5.0.3-d  x86_64  debug=y   Not tainted 
]----
(XEN) [   13.486826] CPU:    0
(XEN) [   13.486828] RIP:    e008:[<ffff82d0802885f4>] switch_cr3_cr4+0x58/0x116
(XEN) [   13.486833] RFLAGS: 0000000000010086   CONTEXT: hypervisor
(XEN) [   13.486836] rax: 00000000000000df   rbx: 0000000000000282   rcx: 
ffff82d0804b7fff
(XEN) [   13.486839] rdx: 0000000000152660   rsi: 00000000001526e0   rdi: 
8000001071d4a000
(XEN) [   13.486841] rbp: ffff82d0804b78d8   rsp: ffff82d0804b78a8   r8:  
0000000000000000
(XEN) [   13.486844] r9:  0000ffff0000ffff   r10: 00ff00ff00ff00ff   r11: 
0f0f0f0f0f0f0f0f
(XEN) [   13.486847] r12: 8000001071d4a000   r13: 0000000057ea8000   r14: 
00000000001526e0
(XEN) [   13.486849] r15: ffff83107326f000   cr0: 000000008005003b   cr4: 
0000000000152660
(XEN) [   13.486851] cr3: 0000000057ea8000   cr2: 0000000000000000
(XEN) [   13.486853] fsb: 0000000000000000   gsb: 0000000000000000   gss: 
0000000000000000
(XEN) [   13.486855] ds: 0000   es: 0000   fs: 0000   gs: 0000   ss: 0000   cs: 
e008
(XEN) [   13.486859] Xen code around <ffff82d0802885f4> 
(switch_cr3_cr4+0x58/0x116):
(XEN) [   13.486860]  00 00 66 0f 38 82 4d d0 <41> 0f 22 dc 4c 39 f2 75 56 4c 
89 ea 81 e2 ff 0f
(XEN) [   13.486869] Xen stack trace from rsp=ffff82d0804b78a8:
(XEN) [   13.486870]    ffff82d0804b78d8 ffff82d0804466a2 ffff83005a1f1000 
0000000000000002
(XEN) [   13.486874]    ffffffff82000000 ffff830000060fa0 ffff82d0804b7d68 
ffff82d08044349e
(XEN) [   13.486878]    0000000000000000 ffff830000060fa0 ffffffff82000000 
0000000000000ff0
(XEN) [   13.486881]    0000000000000000 0000001071d4c000 ffff831071d4b000 
ffff831071d4c000
(XEN) [   13.486884]    ffffffff81d49000 0000000000000000 0000000000000013 
ffff831071d4dff8
(XEN) [   13.486887]    0000001071d5c000 ffff831071d4d000 ffffffff81d5e000 
ffffffff81000000
(XEN) [   13.486891]    0000000001072000 0000001071d5d000 ffffffff81d4a000 
ffffffff81d49000
(XEN) [   13.486894]    ffff831071d4c080 0000000000002000 0000000001070000 
ffffffff81d49000
(XEN) [   13.486897]    ffffffff82000000 ffff831071d4aff8 0000000000002000 
0000000000000001
(XEN) [   13.486900]    0000008000200000 0000008000000000 000000000000570a 
0000000000040000
(XEN) [   13.486903]    0000000000000000 ffffffff80000000 ffff831071d4dff0 
ffff82d080485580
(XEN) [   13.486907]    ffff83005a1f1000 0000000005709ac2 0000000000000000 
ffff832079bd182c
(XEN) [   13.486910]    ffff832079bd19e8 0000000000000000 0000000000000000 
0000000000000000
(XEN) [   13.486913]    0000000000000001 ffff82d0803fd5e8 ffffffff81b051f0 
0000000000000001
(XEN) [   13.486916]    ffff82d0803fd436 ffffffff81001000 0000000000000001 
ffff82d0803fd410
(XEN) [   13.486919]    ffffffff80000000 0000000000000001 ffff82d0803fd429 
0000000000000000
(XEN) [   13.486923]    0000000000000002 ffff82d0803fd578 ffff832079bd1868 
0000000000000002
(XEN) [   13.486926]    ffff82d0803fd3d4 ffff832079bd183c 0000000000000002 
ffff82d0803fd584
(XEN) [   13.486929]    ffff832079bd1854 0000000000000002 ffff82d0803fd3cd 
ffff832079bd1944
(XEN) [   13.486933]    0000000000000002 ffff82d0803fd592 ffff832079bd1930 
0000000000000002
(XEN) [   13.486936] Xen call trace:
(XEN) [   13.486938]    [<ffff82d0802885f4>] switch_cr3_cr4+0x58/0x116
(XEN) [   13.486942]    [<ffff82d08044349e>] dom0_construct_pv+0x1bb1/0x29e3
(XEN) [   13.486945]    [<ffff82d0804470ba>] construct_dom0+0x8c/0xb86
(XEN) [   13.486949]    [<ffff82d080437fd3>] __start_xen+0x23c4/0x2629
(XEN) [   13.486952]    [<ffff82d0802000f3>] __high_start+0x53/0x58
(XEN) [   13.486954]
(XEN) [   14.047278]
(XEN) [   14.049274] ****************************************
(XEN) [   14.054734] Panic on CPU 0:
(XEN) [   14.058026] GENERAL PROTECTION FAULT
(XEN) [   14.062099] [error_code=0000]
(XEN) [   14.065565] ****************************************
(XEN) [   14.071024]
(XEN) [   14.073018] Reboot in five seconds...

The faulting instruction is `mov %r12, %cr3` which is trying to use
noflush while %cr4.pcide is clear.

~Andrew

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel