mirror of
https://git.proxmox.com/git/mirror_ubuntu-kernels.git
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1b78d474ce
Add yet another macro to the VM/vCPU ioctl() framework to detect when an
ioctl() failed because KVM killed/bugged the VM, i.e. when there was
nothing wrong with the ioctl() itself. If KVM kills a VM, e.g. by way of
a failed KVM_BUG_ON(), all subsequent VM and vCPU ioctl()s will fail with
-EIO, which can be quite misleading and ultimately waste user/developer
time.
Use KVM_CHECK_EXTENSION on KVM_CAP_USER_MEMORY to detect if the VM is
dead and/or bug, as KVM doesn't provide a dedicated ioctl(). Using a
heuristic is obviously less than ideal, but practically speaking the logic
is bulletproof barring a KVM change, and any such change would arguably
break userspace, e.g. if KVM returns something other than -EIO.
Without the detection, tearing down a bugged VM yields a cryptic failure
when deleting memslots:
==== Test Assertion Failure ====
lib/kvm_util.c:689: !ret
pid=45131 tid=45131 errno=5 - Input/output error
1 0x00000000004036c3: __vm_mem_region_delete at kvm_util.c:689
2 0x00000000004042f0: kvm_vm_free at kvm_util.c:724 (discriminator 12)
3 0x0000000000402929: race_sync_regs at sync_regs_test.c:193
4 0x0000000000401cab: main at sync_regs_test.c:334 (discriminator 6)
5 0x0000000000416f13: __libc_start_call_main at libc-start.o:?
6 0x000000000041855f: __libc_start_main_impl at ??:?
7 0x0000000000401d40: _start at ??:?
KVM_SET_USER_MEMORY_REGION failed, rc: -1 errno: 5 (Input/output error)
Which morphs into a more pointed error message with the detection:
==== Test Assertion Failure ====
lib/kvm_util.c:689: false
pid=80347 tid=80347 errno=5 - Input/output error
1 0x00000000004039ab: __vm_mem_region_delete at kvm_util.c:689 (discriminator 5)
2 0x0000000000404660: kvm_vm_free at kvm_util.c:724 (discriminator 12)
3 0x0000000000402ac9: race_sync_regs at sync_regs_test.c:193
4 0x0000000000401cb7: main at sync_regs_test.c:334 (discriminator 6)
5 0x0000000000418263: __libc_start_call_main at libc-start.o:?
6 0x00000000004198af: __libc_start_main_impl at ??:?
7 0x0000000000401d90: _start at ??:?
KVM killed/bugged the VM, check the kernel log for clues
Suggested-by: Michal Luczaj <mhal@rbox.co>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Colton Lewis <coltonlewis@google.com>
Link: https://lore.kernel.org/r/20231108010953.560824-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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| .. | ||
| alsa | ||
| amd-pstate | ||
| arm64 | ||
| bpf | ||
| breakpoints | ||
| cachestat | ||
| capabilities | ||
| cgroup | ||
| clone3 | ||
| connector | ||
| core | ||
| cpu-hotplug | ||
| cpufreq | ||
| damon | ||
| dma | ||
| dmabuf-heaps | ||
| drivers | ||
| dt | ||
| efivarfs | ||
| exec | ||
| fchmodat2 | ||
| filelock | ||
| filesystems | ||
| firmware | ||
| fpu | ||
| ftrace | ||
| futex | ||
| gpio | ||
| hid | ||
| ia64 | ||
| intel_pstate | ||
| iommu | ||
| ipc | ||
| ir | ||
| kcmp | ||
| kexec | ||
| kmod | ||
| kselftest | ||
| kvm | ||
| landlock | ||
| lib | ||
| livepatch | ||
| lkdtm | ||
| locking | ||
| media_tests | ||
| membarrier | ||
| memfd | ||
| memory-hotplug | ||
| mincore | ||
| mm | ||
| mount | ||
| mount_setattr | ||
| move_mount_set_group | ||
| mqueue | ||
| nci | ||
| net | ||
| netfilter | ||
| nolibc | ||
| nsfs | ||
| ntb | ||
| openat2 | ||
| perf_events | ||
| pid_namespace | ||
| pidfd | ||
| powerpc | ||
| prctl | ||
| proc | ||
| pstore | ||
| ptp | ||
| ptrace | ||
| rcutorture | ||
| resctrl | ||
| riscv | ||
| rlimits | ||
| rseq | ||
| rtc | ||
| safesetid | ||
| sched | ||
| seccomp | ||
| sgx | ||
| sigaltstack | ||
| size | ||
| sparc64 | ||
| splice | ||
| static_keys | ||
| sync | ||
| syscall_user_dispatch | ||
| sysctl | ||
| tc-testing | ||
| tdx | ||
| thermal/intel | ||
| timens | ||
| timers | ||
| tmpfs | ||
| tpm2 | ||
| tty | ||
| uevent | ||
| user | ||
| user_events | ||
| vDSO | ||
| watchdog | ||
| wireguard | ||
| x86 | ||
| zram | ||
| .gitignore | ||
| gen_kselftest_tar.sh | ||
| kselftest_deps.sh | ||
| kselftest_harness.h | ||
| kselftest_install.sh | ||
| kselftest_module.h | ||
| kselftest.h | ||
| lib.mk | ||
| Makefile | ||
| run_kselftest.sh | ||