From: syzbot ci <syzbot+ci693402a94575bcb2@syzkaller.appspotmail.com>
To: bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com,
jackmanb@google.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, mingo@redhat.com,
pbonzini@redhat.com, seanjc@google.com, tglx@linutronix.de,
x86@kernel.org
Cc: syzbot@lists.linux.dev, syzkaller-bugs@googlegroups.com
Subject: [syzbot ci] Re: KVM: x86: Unify L1TF flushing under per-CPU variable
Date: Mon, 13 Oct 2025 23:13:43 -0700 [thread overview]
Message-ID: <68edea17.050a0220.91a22.01fd.GAE@google.com> (raw)
In-Reply-To: <20251013-b4-l1tf-percpu-v1-1-d65c5366ea1a@google.com>
syzbot ci has tested the following series
[v1] KVM: x86: Unify L1TF flushing under per-CPU variable
https://lore.kernel.org/all/20251013-b4-l1tf-percpu-v1-1-d65c5366ea1a@google.com
* [PATCH] KVM: x86: Unify L1TF flushing under per-CPU variable
and found the following issue:
BUG: using __this_cpu_write() in preemptible code in x86_emulate_instruction
Full report is available here:
https://ci.syzbot.org/series/c0a39c51-4121-4883-a21f-4277f63b3118
***
BUG: using __this_cpu_write() in preemptible code in x86_emulate_instruction
tree: kvm-next
URL: https://kernel.googlesource.com/pub/scm/virt/kvm/kvm/
base: 6b36119b94d0b2bb8cea9d512017efafd461d6ac
arch: amd64
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
config: https://ci.syzbot.org/builds/a964957a-128c-43dd-b6df-7758575a9993/config
C repro: https://ci.syzbot.org/findings/c0c645e8-abe2-437f-aa29-1adf339cb732/c_repro
syz repro: https://ci.syzbot.org/findings/c0c645e8-abe2-437f-aa29-1adf339cb732/syz_repro
BUG: using __this_cpu_write() in preemptible [00000000] code: syz.0.17/5962
caller is kvm_set_cpu_l1tf_flush_l1d arch/x86/include/asm/kvm_host.h:2486 [inline]
caller is x86_emulate_instruction+0x1a4/0x1f70 arch/x86/kvm/x86.c:9405
CPU: 1 UID: 0 PID: 5962 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
check_preemption_disabled+0x10a/0x120 lib/smp_processor_id.c:47
kvm_set_cpu_l1tf_flush_l1d arch/x86/include/asm/kvm_host.h:2486 [inline]
x86_emulate_instruction+0x1a4/0x1f70 arch/x86/kvm/x86.c:9405
kvm_mmu_page_fault+0x91a/0xb70 arch/x86/kvm/mmu/mmu.c:6385
__vmx_handle_exit arch/x86/kvm/vmx/vmx.c:6624 [inline]
vmx_handle_exit+0x10a4/0x18c0 arch/x86/kvm/vmx/vmx.c:6641
vcpu_enter_guest arch/x86/kvm/x86.c:11461 [inline]
vcpu_run+0x4359/0x6fc0 arch/x86/kvm/x86.c:11619
kvm_arch_vcpu_ioctl_run+0xfc9/0x1940 arch/x86/kvm/x86.c:11958
kvm_vcpu_ioctl+0x95c/0xe90 virt/kvm/kvm_main.c:4476
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0f9698eec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff7c8600c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f0f96be5fa0 RCX: 00007f0f9698eec9
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00007f0f96a11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0f96be5fa0 R14: 00007f0f96be5fa0 R15: 0000000000000003
</TASK>
***
If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
Tested-by: syzbot@syzkaller.appspotmail.com
---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.
next prev parent reply other threads:[~2025-10-14 6:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-13 15:20 [PATCH] KVM: x86: Unify L1TF flushing under per-CPU variable Brendan Jackman
2025-10-13 16:31 ` Sean Christopherson
2025-10-13 16:52 ` Brendan Jackman
2025-10-14 6:13 ` syzbot ci [this message]
2025-10-14 8:57 ` [syzbot ci] " Brendan Jackman
2025-10-14 11:46 ` Brendan Jackman
2025-10-14 7:24 ` [PATCH] " kernel test robot
2025-10-14 9:02 ` Brendan Jackman
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