diff options
| author | Claudio Imbrenda <imbrenda@linux.ibm.com> | 2023-07-05 13:19:36 +0200 |
|---|---|---|
| committer | Claudio Imbrenda <imbrenda@linux.ibm.com> | 2023-07-18 11:21:51 +0200 |
| commit | 5ff92181577a89ed12ad4e0e5813751faf16a139 (patch) | |
| tree | 473e3642300005f46841a559417d39cabdf9ca04 /arch | |
| parent | Linux 6.5-rc2 (diff) | |
| download | linux-5ff92181577a89ed12ad4e0e5813751faf16a139.tar.xz linux-5ff92181577a89ed12ad4e0e5813751faf16a139.zip | |
KVM: s390: pv: simplify shutdown and fix race
Simplify the shutdown of non-protected VMs. There is no need to do
complex manipulations of the counter if it was zero.
This also fixes a very rare race which caused pages to be torn down
from the address space with a non-zero counter even on older machines
that don't support the UVC instruction, causing a crash.
Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Fixes: fb491d5500a7 ("KVM: s390: pv: asynchronous destroy for reboot")
Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20230705111937.33472-2-imbrenda@linux.ibm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/s390/kvm/pv.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c index 2f34c7c3c5ab..bf1fdc7bf89e 100644 --- a/arch/s390/kvm/pv.c +++ b/arch/s390/kvm/pv.c @@ -411,8 +411,12 @@ int kvm_s390_pv_deinit_cleanup_all(struct kvm *kvm, u16 *rc, u16 *rrc) u16 _rc, _rrc; int cc = 0; - /* Make sure the counter does not reach 0 before calling s390_uv_destroy_range */ - atomic_inc(&kvm->mm->context.protected_count); + /* + * Nothing to do if the counter was already 0. Otherwise make sure + * the counter does not reach 0 before calling s390_uv_destroy_range. + */ + if (!atomic_inc_not_zero(&kvm->mm->context.protected_count)) + return 0; *rc = 1; /* If the current VM is protected, destroy it */ |