On Fri, Dec 11, 2015 at 11:41:30AM +0100, Paolo Bonzini wrote:
> You can disable it (well, make it take a few days to appear) with this:
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 484079efea5b..a9070e260c72 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -496,7 +496,7 @@ static struct kvm_memslots *kvm_alloc_memslots(void)
> * Init kvm generation close to the maximum to easily test the
> * code of handling generation number wrap-around.
> */
> - slots->generation = -150;
> + slots->generation = 0;
> for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)
> slots->id_to_index[i] = slots->memslots[i].id = i;
>
> but it would not be AMD-specific.
Yeah, that didn't help. This time the splat is a bit more interesting:
qemu process segfaulted at a kernel address - ffffffff816e2db1 - which
is the last insn of entry_SYSCALL_64_fastpath:
ffffffff816e2d45 <entry_SYSCALL_64_fastpath>:
ffffffff816e2d45: 25 ff ff ff bf and $0xbfffffff,%eax
ffffffff816e2d4a: 3d 21 02 00 00 cmp $0x221,%eax
...
ffffffff816e2d9e: 4c 8b 9c 24 90 00 00 mov 0x90(%rsp),%r11
ffffffff816e2da5: 00
ffffffff816e2da6: 48 8b a4 24 98 00 00 mov 0x98(%rsp),%rsp
ffffffff816e2dad: 00
ffffffff816e2dae: 0f 01 f8 swapgs
ffffffff816e2db1: 48 0f 07 sysretq
Yap, at SYSRET.
Andy might find this a little amusing :-)
[ 459.130565] qemu-system-x86[3724]: segfault at ffffffff816e2db1 ip ffffffff816e2db1 sp 00007fd593ffe970 error 15
[ 512.578297] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 512.586189] IP: [< (null)>] (null)
[ 512.591266] PGD 0
[ 512.593303] Oops: 0010 [#1] PREEMPT SMP
[ 512.597283] Modules linked in: tun sha256_ssse3 sha256_generic drbg binfmt_misc ipv6 vfat fat fuse dm_crypt dm_mod kvm_amd kvm irqbypass crc32_pclmul aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd amd64_edac_mod k10temp edac_mce_amd fam15h_power amdkfd amd_iommu_v2 radeon acpi_cpufreq
[ 512.601698] CPU: 5 PID: 3787 Comm: qemu-system-x86 Not tainted 4.4.0-rc4+ #8
[ 512.601699] Hardware name: To be filled by O.E.M. To be filled by O.E.M./M5A97 EVO R2.0, BIOS 1503 01/16/2013
[ 512.601700] task: ffff8800b5d04680 ti: ffff88041104c000 task.ti: ffff88041104c000
[ 512.601701] RIP: 0010:[<0000000000000000>]
[ 512.601701] [< (null)>] (null)
[ 512.601702] RSP: 0018:ffff88041104fcc0 EFLAGS: 00010212
[ 512.601703] RAX: 0000000000000040 RBX: ffff8804110b4000 RCX: 0000000000000000
[ 512.601703] RDX: 0000000000000000 RSI: ffff8804110b4000 RDI: ffff88041104fc20
[ 512.601704] RBP: ffff88041104fcc8 R08: 0000000000000001 R09: 0000000000000000
[ 512.601704] R10: 0000000000000001 R11: 0000000000000001 R12: 00000000ffffffff
[ 512.601705] R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000001
[ 512.601706] FS: 00007fb0deaf4700(0000) GS:ffff88042d000000(0000) knlGS:0000000000000000
[ 512.601706] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 512.601707] CR2: 0000000000000000 CR3: 0000000428118000 CR4: 00000000000406e0
[ 512.601707] Stack:
[ 512.601708] ffffffffa02b2d3c
[ 512.601708] ffff88041104fdd8
[ 512.601709] ffffffffa02b2d0e
[ 512.601709] ffffffffa02b2c9a
[ 512.601710] ffff8804110b4430
[ 512.601710] 0000000000000000
[ 512.601710] 0000000100000004
[ 512.601711] ffffffffa02e9bb0
[ 512.601711] 0000000400000002
[ 512.601711] 0000000000000000
[ 512.601712] 0000000000000000
[ 512.601712] 0000000000000000
[ 512.601713] Call Trace:
[ 512.601729] [<ffffffffa02b2d3c>] ? kvm_set_irq+0x13c/0x250 [kvm]
[ 512.601736] [<ffffffffa02b2d0e>] kvm_set_irq+0x10e/0x250 [kvm]
[ 512.601744] [<ffffffffa02b2c9a>] ? kvm_set_irq+0x9a/0x250 [kvm]
[ 512.601756] [<ffffffffa02e9bb0>] ? kvm_set_msi_irq+0x1b0/0x1b0 [kvm]
[ 512.601767] [<ffffffffa02e9bd0>] ? kvm_set_ioapic_irq+0x20/0x20 [kvm]
[ 512.601776] [<ffffffffa02c2612>] kvm_vm_ioctl_irq_line+0x32/0x40 [kvm]
[ 512.601783] [<ffffffffa02af97b>] kvm_vm_ioctl+0x5eb/0x820 [kvm]
[ 512.601786] [<ffffffff810c6a25>] ? rcu_read_lock_held+0x45/0x60
[ 512.601788] [<ffffffff811a0930>] do_vfs_ioctl+0x2e0/0x540
[ 512.601790] [<ffffffff811ac8e9>] ? __fget_light+0x29/0x90
[ 512.601791] [<ffffffff811a0bdc>] SyS_ioctl+0x4c/0x90
[ 512.601794] [<ffffffff816e2d5b>] entry_SYSCALL_64_fastpath+0x16/0x6f
[ 512.601797] Code: Bad RIP value.
[ 512.601798] RIP [< (null)>] (null)
[ 512.601798] RSP <ffff88041104fcc0>
[ 512.601799] CR2: 0000000000000000
[ 512.609862] ---[ end trace ae4f00b514141891 ]---
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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