diff options
| author | Claudio Imbrenda <imbrenda@linux.ibm.com> | 2026-06-02 16:23:52 +0200 |
|---|---|---|
| committer | Claudio Imbrenda <imbrenda@linux.ibm.com> | 2026-06-02 16:46:41 +0200 |
| commit | 9a1dfbbd3506c4f7159feab5ef27434e80256fa5 (patch) | |
| tree | d2b23e928411c3e2d69e505d9fbb823df093f44e | |
| parent | 6af5563e827913d3e14dbf12eefd5af4aa592739 (diff) | |
KVM: s390: Fix fault-in code
Fix the fault-in code so that it does not return success if a
concurrent unmap event invalidated the fault-in process between the
best-effort lockless check and the proper check with lock.
The new behaviour is to retry, like the best-effort lockless check
already did.
This prevents the fault-in handler from returning success without
having actually faulted in the requested page.
Fixes: e907ae530133 ("KVM: s390: Add helper functions for fault handling")
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260602142356.169458-7-imbrenda@linux.ibm.com>
| -rw-r--r-- | arch/s390/kvm/faultin.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/arch/s390/kvm/faultin.c b/arch/s390/kvm/faultin.c index ddf0ca71f374..cf542b0a7e8e 100644 --- a/arch/s390/kvm/faultin.c +++ b/arch/s390/kvm/faultin.c @@ -36,7 +36,8 @@ int kvm_s390_faultin_gfn(struct kvm_vcpu *vcpu, struct kvm *kvm, struct guest_fa struct kvm_s390_mmu_cache *mc = NULL; struct kvm_memory_slot *slot; unsigned long inv_seq; - int foll, rc = 0; + int rc = -EAGAIN; + int foll; foll = f->write_attempt ? FOLL_WRITE : 0; foll |= f->attempt_pfault ? FOLL_NOWAIT : 0; @@ -53,7 +54,7 @@ int kvm_s390_faultin_gfn(struct kvm_vcpu *vcpu, struct kvm *kvm, struct guest_fa return 0; } - while (1) { + while (rc == -EAGAIN) { f->valid = false; inv_seq = kvm->mmu_invalidate_seq; /* Pairs with the smp_wmb() in kvm_mmu_invalidate_end(). */ @@ -110,20 +111,19 @@ int kvm_s390_faultin_gfn(struct kvm_vcpu *vcpu, struct kvm *kvm, struct guest_fa if (!mmu_invalidate_retry_gfn(kvm, inv_seq, f->gfn)) { f->valid = true; rc = gmap_link(mc, kvm->arch.gmap, f, slot); - kvm_release_faultin_page(kvm, f->page, !!rc, f->write_attempt); - f->page = NULL; } + kvm_release_faultin_page(kvm, f->page, !!rc, f->write_attempt); } - kvm_release_faultin_page(kvm, f->page, true, false); if (rc == -ENOMEM) { rc = kvm_s390_mmu_cache_topup(mc); if (rc) return rc; - } else if (rc != -EAGAIN) { - return rc; + rc = -EAGAIN; } } + + return rc; } int kvm_s390_get_guest_page(struct kvm *kvm, struct guest_fault *f, gfn_t gfn, bool w) |