uffd: Set unprivileged_userfaultfd sysctl knob to 1 if kernel faults must be handled without obtaining CAP_SYS_PTRACE capability
------------[ cut here ]------------
WARNING: CPU: 0 PID: 4925 at arch/x86/kvm/../../../virt/kvm/kvm_main.c:3087 kvm_write_guest_offset_cached+0x507/0x5d0 virt/kvm/kvm_main.c:3087
Modules linked in:
CPU: 0 PID: 4925 Comm: syz.2.103 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:kvm_write_guest_offset_cached+0x507/0x5d0 virt/kvm/kvm_main.c:3087
Code: 00 c6 05 1e 8e 6e 0c 01 48 c7 c7 00 ee 21 8a be 7a 03 00 00 48 c7 c2 a0 cd 21 8a e8 43 9e ac 08 e9 a1 fb ff ff e8 29 58 70 00 <0f> 0b b8 ea ff ff ff eb b0 e8 1b 58 70 00 48 8b 7c 24 08 48 89 ee
RSP: 0018:ffffc90003c1f108 EFLAGS: 00010283
RAX: ffffffff8108a957 RBX: 0000000000000004 RCX: 0000000000080000
RDX: ffffc9000e3e9000 RSI: 0000000000003836 RDI: 0000000000003837
RBP: 0000000000000000 R08: ffffc90003c2bf4b R09: 1ffff920007857e9
R10: dffffc0000000000 R11: fffff520007857ea R12: 0000000000000000
R13: 0000000000000000 R14: ffff88805ecadcd8 R15: dffffc0000000000
FS:  00007f679abd66c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000558fd2f7fee8 CR3: 0000000062607000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 apf_put_user_notpresent arch/x86/kvm/x86.c:12314 [inline]
 kvm_arch_async_page_not_present+0x354/0x5e0 arch/x86/kvm/x86.c:12376
 kvm_setup_async_pf+0x39c/0x480 virt/kvm/async_pf.c:217
 kvm_arch_setup_async_pf arch/x86/kvm/mmu/mmu.c:3907 [inline]
 kvm_faultin_pfn+0x730/0xb80 arch/x86/kvm/mmu/mmu.c:3958
 direct_page_fault+0x1252/0x1750 arch/x86/kvm/mmu/mmu.c:3998
 kvm_mmu_do_page_fault arch/x86/kvm/mmu.h:128 [inline]
 kvm_mmu_page_fault+0x126/0x5b0 arch/x86/kvm/mmu/mmu.c:5295
 __vmx_handle_exit arch/x86/kvm/vmx/vmx.c:6171 [inline]
 vmx_handle_exit+0xc44/0x18a0 arch/x86/kvm/vmx/vmx.c:6188
 vcpu_enter_guest+0x60cd/0x6f70 arch/x86/kvm/x86.c:10102
 vcpu_run arch/x86/kvm/x86.c:10192 [inline]
 kvm_arch_vcpu_ioctl_run+0x804/0x1e40 arch/x86/kvm/x86.c:10432
 kvm_vcpu_ioctl+0x8f2/0xc10 virt/kvm/kvm_main.c:3894
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f679c97de99
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f679abd6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f679cc05fa0 RCX: 00007f679c97de99
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00007f679ca13eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f679cc06038 R14: 00007f679cc05fa0 R15: 00007ffc47626648
 </TASK>