On 25/07/2022 16:51, Bertrand Marquis wrote: > Hi, > > On our CI we have randomly a crash during guest boot on x86. > > We are running on qemu x86_64 using Xen staging. > The crash is happening randomly (something like 1 out of 20 times). > > This is always happening on the first guest we start, we never got it after > first guest was successfully started. > > Please tell me if you need any other info. > > Here is the guest kernel log: > <snip> > [ 0.000000] Hypervisor detected: Xen PV > <snip> > [ 6.679020] general protection fault, maybe for address 0x8800: 0000 [#1] > PREEMPT SMP NOPTI > [ 6.679020] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.17.6 #1 > [ 6.679020] RIP: e030:error_entry+0xaf/0xe0 > [ 6.679020] Code: 29 89 c8 48 39 84 24 88 00 00 00 74 15 48 81 bc 24 88 00 > 00 00 63 10 e0 81 75 03 0f 01 f8 90 90 90 c3 48 89 8c 24 88 00 00 00 <0f> 01 > f8 90 90 90 eb 11 0f 20 d8 90 90 90 90 90 48 25 ff e7 ff ff > [ 6.679020] RSP: e02b:ffffffff82803a90 EFLAGS: 00000046 > [ 6.679020] RAX: 0000000000008800 RBX: 0000000000000000 RCX: > ffffffff81e00fa7 > [ 6.679020] RDX: 0000000000000000 RSI: ffffffff81e009f8 RDI: > 00000000000000eb > [ 6.679020] RBP: 0000000000000000 R08: 0000000000000000 R09: > 0000000000000000 > [ 6.679020] R10: 0000000000000000 R11: 0000000000000000 R12: > 0000000000000000 > [ 6.679020] R13: 0000000000000000 R14: 0000000000000000 R15: > 0000000000000000 > [ 6.679020] FS: 0000000000000000(0000) GS:ffff88801f200000(0000) > knlGS:0000000000000000 > [ 6.679020] CS: 10000e030 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 6.679020] CR2: 0000000000000000 CR3: 000000000280c000 CR4: > 0000000000050660 > [ 6.679020] Call Trace: > [ 6.679020] <TASK> >
0f 01 f8 is SWAPGS This is a privileged instruction, and has never been permitted under Xen PV. This should have been excluded by pvops. This is a Linux bug, not a Xen bug. I can't explain why you're only seeing it intermittently. Perhaps error_entry is broken by default, and pvops fixes things up, but an error early enough takes a non-fixed-up path :-/ ~Andrew
