From: Halil Pasic pasic@linux.ibm.com
commit a3e03bc1368c1bc16e19b001fc96dc7430573cc8 upstream.
While in practice vcpu->vcpu_idx == vcpu->vcp_id is often true, it may not always be, and we must not rely on this. Reason is that KVM decides the vcpu_idx, userspace decides the vcpu_id, thus the two might not match.
Currently kvm->arch.idle_mask is indexed by vcpu_id, which implies that code like for_each_set_bit(vcpu_id, kvm->arch.idle_mask, online_vcpus) { vcpu = kvm_get_vcpu(kvm, vcpu_id); do_stuff(vcpu); } is not legit. Reason is that kvm_get_vcpu expects an vcpu_idx, not an vcpu_id. The trouble is, we do actually use kvm->arch.idle_mask like this. To fix this problem we have two options. Either use kvm_get_vcpu_by_id(vcpu_id), which would loop to find the right vcpu_id, or switch to indexing via vcpu_idx. The latter is preferable for obvious reasons.
Let us make switch from indexing kvm->arch.idle_mask by vcpu_id to indexing it by vcpu_idx. To keep gisa_int.kicked_mask indexed by the same index as idle_mask lets make the same change for it as well.
Fixes: 1ee0bc559dc3 ("KVM: s390: get rid of local_int array") Signed-off-by: Halil Pasic pasic@linux.ibm.com Reviewed-by: Christian Bornträger borntraeger@de.ibm.com Reviewed-by: Claudio Imbrenda imbrenda@linux.ibm.com Cc: stable@vger.kernel.org # 3.15+ Link: https://lore.kernel.org/r/20210827125429.1912577-1-pasic@linux.ibm.com Signed-off-by: Christian Borntraeger borntraeger@de.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/s390/include/asm/kvm_host.h | 1 + arch/s390/kvm/interrupt.c | 12 ++++++------ arch/s390/kvm/kvm-s390.c | 2 +- arch/s390/kvm/kvm-s390.h | 2 +- 4 files changed, 9 insertions(+), 8 deletions(-)
--- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -873,6 +873,7 @@ struct kvm_arch{ atomic64_t cmma_dirty_pages; /* subset of available cpu features enabled by user space */ DECLARE_BITMAP(cpu_feat, KVM_S390_VM_CPU_FEAT_NR_BITS); + /* indexed by vcpu_idx */ DECLARE_BITMAP(idle_mask, KVM_MAX_VCPUS); struct kvm_s390_gisa_interrupt gisa_int; }; --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -408,13 +408,13 @@ static unsigned long deliverable_irqs(st static void __set_cpu_idle(struct kvm_vcpu *vcpu) { kvm_s390_set_cpuflags(vcpu, CPUSTAT_WAIT); - set_bit(vcpu->vcpu_id, vcpu->kvm->arch.idle_mask); + set_bit(kvm_vcpu_get_idx(vcpu), vcpu->kvm->arch.idle_mask); }
static void __unset_cpu_idle(struct kvm_vcpu *vcpu) { kvm_s390_clear_cpuflags(vcpu, CPUSTAT_WAIT); - clear_bit(vcpu->vcpu_id, vcpu->kvm->arch.idle_mask); + clear_bit(kvm_vcpu_get_idx(vcpu), vcpu->kvm->arch.idle_mask); }
static void __reset_intercept_indicators(struct kvm_vcpu *vcpu) @@ -2984,18 +2984,18 @@ int kvm_s390_get_irq_state(struct kvm_vc
static void __airqs_kick_single_vcpu(struct kvm *kvm, u8 deliverable_mask) { - int vcpu_id, online_vcpus = atomic_read(&kvm->online_vcpus); + int vcpu_idx, online_vcpus = atomic_read(&kvm->online_vcpus); struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int; struct kvm_vcpu *vcpu;
- for_each_set_bit(vcpu_id, kvm->arch.idle_mask, online_vcpus) { - vcpu = kvm_get_vcpu(kvm, vcpu_id); + for_each_set_bit(vcpu_idx, kvm->arch.idle_mask, online_vcpus) { + vcpu = kvm_get_vcpu(kvm, vcpu_idx); if (psw_ioint_disabled(vcpu)) continue; deliverable_mask &= (u8)(vcpu->arch.sie_block->gcr[6] >> 24); if (deliverable_mask) { /* lately kicked but not yet running */ - if (test_and_set_bit(vcpu_id, gi->kicked_mask)) + if (test_and_set_bit(vcpu_idx, gi->kicked_mask)) return; kvm_s390_vcpu_wakeup(vcpu); return; --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -3726,7 +3726,7 @@ static int vcpu_pre_run(struct kvm_vcpu kvm_s390_patch_guest_per_regs(vcpu); }
- clear_bit(vcpu->vcpu_id, vcpu->kvm->arch.gisa_int.kicked_mask); + clear_bit(kvm_vcpu_get_idx(vcpu), vcpu->kvm->arch.gisa_int.kicked_mask);
vcpu->arch.sie_block->icptcode = 0; cpuflags = atomic_read(&vcpu->arch.sie_block->cpuflags); --- a/arch/s390/kvm/kvm-s390.h +++ b/arch/s390/kvm/kvm-s390.h @@ -67,7 +67,7 @@ static inline int is_vcpu_stopped(struct
static inline int is_vcpu_idle(struct kvm_vcpu *vcpu) { - return test_bit(vcpu->vcpu_id, vcpu->kvm->arch.idle_mask); + return test_bit(kvm_vcpu_get_idx(vcpu), vcpu->kvm->arch.idle_mask); }
static inline int kvm_is_ucontrol(struct kvm *kvm)