Re: [kvm-ppc-devel] [PATCH] Fix signal handing line KVM PowerPC

[Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>]

Hollis Blanchard wrote:
> On Mon, 2008-02-04 at 20:00 -0600, Hollis Blanchard wrote:
>> On Fri, 2008-02-01 at 15:48 -0600, Jerone Young wrote:
>>> Code was missing for our kernel code to properly handle signals, by
>>> setting the signal mask and saving off our current one, then restoring
>>> it at the end. This code does what x86 does and now keyboard input
>>> works.
>>>
>>> Signed-off-by: Jerone Young <jyoung5@us.ibm.com>
>>>
>>>
>>> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
>>> --- a/arch/powerpc/kvm/powerpc.c
>>> +++ b/arch/powerpc/kvm/powerpc.c
>>> @@ -685,6 +688,10 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_v
>>>  int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
>>>  {
>>>         int r;
>>> +       sigset_t sigsaved;
>>> +
>>> +       if (vcpu->sigset_active)
>>> +               sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);
>>>
>>>         if (vcpu->mmio_needed) {
>>>                 if (!vcpu->mmio_is_write)
>>> @@ -702,6 +709,10 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_v
>>>
>>>         r = __kvmppc_vcpu_run(run, vcpu);
>>>         local_irq_enable(); /* XXX */
>>> +
>>> +         
>>> +       if (vcpu->sigset_active)
>>> +               sigprocmask(SIG_SETMASK, &sigsaved, NULL);
>>>
>>>         return r;
>>>  }
>> Applied, thanks. Please watch your whitespace in the future though
>> (including in your mailer :).
> 
> I had to revert this because it caused guest output to "pause" until a
> qemu keypress.
> 

FYI - While I'm at looking into this I found that when I apply this patch my guest get an oops because it gets an unexpected signal in the (guest)kernel.
The same guest/host combination just without that patch works, maybe this helps us debugging this.

Guest Output
[...]
PCI: Probing PCI hardware
NET: Registered protocol family 2
IP route cache hash table entries: 2048 (order: 1, 8192 bytes)
TCP estalished hash table entries: 8192 (order: 4, 65536 bytes)
TCP bind hash table entries: 8192 (order: 3, 32768 bytes)
TCP: Hash tables configured (established 8192 bind 8192)
TCP reno registered
trap!
Oops: Exception in kernel mode, sig: 4 [#1]
Bamboo
Modules linked in:
NIP: c0035d8c LR: c0027cbc CTR: 00000000
REGS: c06a5b40 TRAP: 0700   Not tainted  (2.6.23-rc1)
MSR: 00029002 <EE,ME>  CR: 84000022  XER: 20000000
TASK = c06b9530[2] 'kthreadd' THREAD: c06a4000
GPR00: 00000001 c06a5bf0 c06b9530 c06a5bf8 000005b5 00000000 00000000 00000000
GPR08: 000005b5 000005af 00000005 00000020 f26abea8 00000000 c0276130 00000000
GPR16: c0270000 c0270000 c0276138 c06a5d10 c06a5ef0 c06a5fa0 c06bf2d0 c0270000
GPR24: fffffff4 00000611 c0270000 00800711 c06a5bf8 000000d0 00000000 c06b9530
NIP [c0035d8c] run_posix_cpu_timers+0x2c/0x7dc
LR [c0027cbc] update_process_times+0xa0/0xb4
Call Trace:
[c06a5bf0] [003dacde] 0x3dacde (unreliable)
[c06a5c40] [c0027cbc] update_process_times+0xa0/0xb4
[c06a5c60] [c000968c] timer_interrupt+0xc4/0x558
[c06a5d00] [c000c570] ret_from_except+0x0/0x18
[c06a5dc0] [c0036be8] ktime_get_ts+0x2c/0x74
[c06a5de0] [c001bbe4] copy_process+0x94/0xec8
[c06a5e60] [c001cabc] do_fork+0x6c/0x1d8
[c06a5eb0] [c0005938] sys_clone+0x68/0x84
[c06a5ee0] [c000bf34] ret_from_syscall+0x0/0x3c
[c06a5fa0] [c06a3e84] 0xc06a3e84
[c06a5fb0] [c0033dc0] kthreadd+0xd8/0xdc
[c06a5ff0] [c000cff0] kernel_thread+0x48/0x64
Instruction dump:
4bffffe0 7c0802a6 9421ffb0 be810020 3b810008 7c7f1b78 93810008 90010054
7f83e378 9381000c 7c0000a6 54008ffe <0f000000> 817f01b0 2f8b0000 419e05f0
Kernel panic - not syncing: Fatal exception in interrupt



-- 

Grüsse / regards, 
Christian Ehrhardt
IBM Linux Technology Center, Open Virtualization

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