[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v3 0/1] xen: fix HVM kexec kernel panic
On 2/25/22 8:17 PM, Dongli Zhang wrote: Hi Boris, On 2/25/22 2:39 PM, Boris Ostrovsky wrote:On 2/24/22 4:50 PM, Dongli Zhang wrote:This is the v3 of the patch to fix xen kexec kernel panic issue when the kexec is triggered on VCPU >= 32. PANIC: early exception 0x0e IP 10:ffffffffa96679b6 error 0 cr2 0x20 [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.17.0-rc4xen-00054-gf71077a4d84b-dirty #1 [ 0.000000] Hardware name: Xen HVM domU, BIOS 4.4.4OVM 12/15/2020 [ 0.000000] RIP: 0010:pvclock_clocksource_read+0x6/0xb0 ... ... [ 0.000000] RSP: 0000:ffffffffaae03e10 EFLAGS: 00010082 ORIG_RAX: 0000000000000000 [ 0.000000] RAX: 0000000000000000 RBX: 0000000000010000 RCX: 0000000000000002 [ 0.000000] RDX: 0000000000000003 RSI: ffffffffaac37515 RDI: 0000000000000020 [ 0.000000] RBP: 0000000000011000 R08: 0000000000000000 R09: 0000000000000001 [ 0.000000] R10: ffffffffaae03df8 R11: ffffffffaae03c68 R12: 0000000040000004 [ 0.000000] R13: ffffffffaae03e50 R14: 0000000000000000 R15: 0000000000000000 [ 0.000000] FS: 0000000000000000(0000) GS:ffffffffab588000(0000) knlGS:0000000000000000 [ 0.000000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.000000] CR2: 0000000000000020 CR3: 00000000ea410000 CR4: 00000000000406a0 [ 0.000000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 0.000000] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 0.000000] Call Trace: [ 0.000000] <TASK> [ 0.000000] ? xen_clocksource_read+0x24/0x40This is done to set xen_sched_clock_offset which I think will not be used for a while, until sched_clock is called (and the other two uses are for suspend/resume) Can we simply defer 'xen_sched_clock_offset = xen_clocksource_read();' until after all vcpu areas are properly set? Or are there other uses of xen_clocksource_read() before ?I have tested that below patch will panic kdump kernel. Oh well, so much for that then. Yes, sched_clock() is at least called from printk path. I guess we will have to go with v2 then, we don't want to start seeing time going back, even if only with older hypervisors. The only thing I might ask is that you roll the logic inside xen_hvm_init_time_ops(). Something like xen_hvm_init_time_ops() { /* * Wait until per_cpu(xen_vcpu, 0) is initialized which may happen * later (e.g. when kdump kernel runs on >=MAX_VIRT_CPUS vcpu) */ if (__this_cpu_read(xen_vcpu_nr(0)) == NULL) return; ... -boris
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