* [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index
@ 2021-09-20 15:06 Christian Borntraeger
2021-09-20 15:06 ` [PATCH 1/1] KVM: s390: index kvm->arch.idle_mask by vcpu_idx Christian Borntraeger
` (2 more replies)
0 siblings, 3 replies; 8+ messages in thread
From: Christian Borntraeger @ 2021-09-20 15:06 UTC (permalink / raw)
To: stable, Paolo Bonzini
Cc: gregkh, KVM, Cornelia Huck, Christian Borntraeger, Janosch Frank,
David Hildenbrand, linux-s390, Thomas Huth, Claudio Imbrenda,
Radim Krčmář,
Nitesh Narayan Lal, Halil Pasic
Stable team,
here is a backport for 4.19 of
commit a3e03bc1368 ("KVM: s390: index kvm->arch.idle_mask by vcpu_idx")
This basically removes the kick_mask parts that were introduced with
kernel 5.0 and fixes up the location of the idle_mask to the older
place.
FWIW, it might be a good idea to also backport
8750e72a79dd ("KVM: remember position in kvm->vcpus array") to avoid
a performance regression for large guests (many vCPUs) when this patch
is applied.
@Paolo Bonzini, would you be ok with 8750e72a79dd in older stable releases?
Halil Pasic (1):
KVM: s390: index kvm->arch.idle_mask by vcpu_idx
arch/s390/kvm/interrupt.c | 4 ++--
arch/s390/kvm/kvm-s390.h | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)
--
2.31.1
^ permalink raw reply [flat|nested] 8+ messages in thread* [PATCH 1/1] KVM: s390: index kvm->arch.idle_mask by vcpu_idx 2021-09-20 15:06 [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index Christian Borntraeger @ 2021-09-20 15:06 ` Christian Borntraeger 2021-09-21 2:43 ` Halil Pasic 2021-09-20 15:24 ` [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index Greg KH 2021-09-20 18:05 ` Paolo Bonzini 2 siblings, 1 reply; 8+ messages in thread From: Christian Borntraeger @ 2021-09-20 15:06 UTC (permalink / raw) To: stable Cc: gregkh, KVM, Cornelia Huck, Christian Borntraeger, Janosch Frank, David Hildenbrand, linux-s390, Thomas Huth, Claudio Imbrenda, Paolo Bonzini, Halil Pasic, Radim Krčmář, Nitesh Narayan Lal From: Halil Pasic <pasic@linux.ibm.com> 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> [borntraeger@de.ibm.com]: change idle mask, remove kicked_mask --- arch/s390/kvm/interrupt.c | 4 ++-- arch/s390/kvm/kvm-s390.h | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 3515f2b55eb9..dc5ecaea30d7 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -318,13 +318,13 @@ static unsigned long deliverable_irqs(struct kvm_vcpu *vcpu) static void __set_cpu_idle(struct kvm_vcpu *vcpu) { kvm_s390_set_cpuflags(vcpu, CPUSTAT_WAIT); - set_bit(vcpu->vcpu_id, vcpu->kvm->arch.float_int.idle_mask); + set_bit(kvm_vcpu_get_idx(vcpu), vcpu->kvm->arch.float_int.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.float_int.idle_mask); + clear_bit(kvm_vcpu_get_idx(vcpu), vcpu->kvm->arch.float_int.idle_mask); } static void __reset_intercept_indicators(struct kvm_vcpu *vcpu) diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h index 981e3ba97461..0a2ffd5378be 100644 --- 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 kvm_vcpu *vcpu) static inline int is_vcpu_idle(struct kvm_vcpu *vcpu) { - return test_bit(vcpu->vcpu_id, vcpu->kvm->arch.float_int.idle_mask); + return test_bit(kvm_vcpu_get_idx(vcpu), vcpu->kvm->arch.float_int.idle_mask); } static inline int kvm_is_ucontrol(struct kvm *kvm) -- 2.31.1 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 1/1] KVM: s390: index kvm->arch.idle_mask by vcpu_idx 2021-09-20 15:06 ` [PATCH 1/1] KVM: s390: index kvm->arch.idle_mask by vcpu_idx Christian Borntraeger @ 2021-09-21 2:43 ` Halil Pasic 0 siblings, 0 replies; 8+ messages in thread From: Halil Pasic @ 2021-09-21 2:43 UTC (permalink / raw) To: Christian Borntraeger Cc: stable, gregkh, KVM, Cornelia Huck, Janosch Frank, David Hildenbrand, linux-s390, Thomas Huth, Claudio Imbrenda, Paolo Bonzini, Radim Krčmář, Nitesh Narayan Lal, Halil Pasic On Mon, 20 Sep 2021 17:06:16 +0200 Christian Borntraeger <borntraeger@de.ibm.com> wrote: > 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> > [borntraeger@de.ibm.com]: change idle mask, remove kicked_mask LGTM. Thanks for taking care of this! ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index 2021-09-20 15:06 [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index Christian Borntraeger 2021-09-20 15:06 ` [PATCH 1/1] KVM: s390: index kvm->arch.idle_mask by vcpu_idx Christian Borntraeger @ 2021-09-20 15:24 ` Greg KH 2021-09-20 15:30 ` Christian Borntraeger 2021-09-20 18:05 ` Paolo Bonzini 2 siblings, 1 reply; 8+ messages in thread From: Greg KH @ 2021-09-20 15:24 UTC (permalink / raw) To: Christian Borntraeger Cc: stable, Paolo Bonzini, KVM, Cornelia Huck, Janosch Frank, David Hildenbrand, linux-s390, Thomas Huth, Claudio Imbrenda, Radim Krčmář, Nitesh Narayan Lal, Halil Pasic On Mon, Sep 20, 2021 at 05:06:15PM +0200, Christian Borntraeger wrote: > Stable team, > > here is a backport for 4.19 of > commit a3e03bc1368 ("KVM: s390: index kvm->arch.idle_mask by vcpu_idx") > This basically removes the kick_mask parts that were introduced with > kernel 5.0 and fixes up the location of the idle_mask to the older > place. Now queued up, thanks. > FWIW, it might be a good idea to also backport > 8750e72a79dd ("KVM: remember position in kvm->vcpus array") to avoid > a performance regression for large guests (many vCPUs) when this patch > is applied. > @Paolo Bonzini, would you be ok with 8750e72a79dd in older stable releases? That would also have to go into 5.4.y, right? thanks, greg k-h ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index 2021-09-20 15:24 ` [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index Greg KH @ 2021-09-20 15:30 ` Christian Borntraeger 0 siblings, 0 replies; 8+ messages in thread From: Christian Borntraeger @ 2021-09-20 15:30 UTC (permalink / raw) To: Greg KH Cc: stable, Paolo Bonzini, KVM, Cornelia Huck, Janosch Frank, David Hildenbrand, linux-s390, Thomas Huth, Claudio Imbrenda, Radim Krčmář, Nitesh Narayan Lal, Halil Pasic Am 20.09.21 um 17:24 schrieb Greg KH: > On Mon, Sep 20, 2021 at 05:06:15PM +0200, Christian Borntraeger wrote: >> Stable team, >> >> here is a backport for 4.19 of >> commit a3e03bc1368 ("KVM: s390: index kvm->arch.idle_mask by vcpu_idx") >> This basically removes the kick_mask parts that were introduced with >> kernel 5.0 and fixes up the location of the idle_mask to the older >> place. > > Now queued up, thanks. > >> FWIW, it might be a good idea to also backport >> 8750e72a79dd ("KVM: remember position in kvm->vcpus array") to avoid >> a performance regression for large guests (many vCPUs) when this patch >> is applied. >> @Paolo Bonzini, would you be ok with 8750e72a79dd in older stable releases? > > That would also have to go into 5.4.y, right? Ideally yes. ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index 2021-09-20 15:06 [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index Christian Borntraeger 2021-09-20 15:06 ` [PATCH 1/1] KVM: s390: index kvm->arch.idle_mask by vcpu_idx Christian Borntraeger 2021-09-20 15:24 ` [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index Greg KH @ 2021-09-20 18:05 ` Paolo Bonzini 2021-09-21 8:46 ` Christian Borntraeger 2 siblings, 1 reply; 8+ messages in thread From: Paolo Bonzini @ 2021-09-20 18:05 UTC (permalink / raw) To: Christian Borntraeger, stable Cc: gregkh, KVM, Cornelia Huck, Janosch Frank, David Hildenbrand, linux-s390, Thomas Huth, Claudio Imbrenda, Radim Krčmář, Nitesh Narayan Lal, Halil Pasic On 20/09/21 17:06, Christian Borntraeger wrote: > here is a backport for 4.19 of > commit a3e03bc1368 ("KVM: s390: index kvm->arch.idle_mask by vcpu_idx") > This basically removes the kick_mask parts that were introduced with > kernel 5.0 and fixes up the location of the idle_mask to the older > place. > > FWIW, it might be a good idea to also backport > 8750e72a79dd ("KVM: remember position in kvm->vcpus array") to avoid > a performance regression for large guests (many vCPUs) when this patch > is applied. > @Paolo Bonzini, would you be ok with 8750e72a79dd in older stable releases? Sure, I suppose you're going to send a separate backport that I can ack. Paolo ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index 2021-09-20 18:05 ` Paolo Bonzini @ 2021-09-21 8:46 ` Christian Borntraeger 2021-09-21 13:04 ` Paolo Bonzini 0 siblings, 1 reply; 8+ messages in thread From: Christian Borntraeger @ 2021-09-21 8:46 UTC (permalink / raw) To: Paolo Bonzini, stable Cc: gregkh, KVM, Cornelia Huck, Janosch Frank, David Hildenbrand, linux-s390, Thomas Huth, Claudio Imbrenda, Radim Krčmář, Nitesh Narayan Lal, Halil Pasic Am 20.09.21 um 20:05 schrieb Paolo Bonzini: > On 20/09/21 17:06, Christian Borntraeger wrote: >> here is a backport for 4.19 of >> commit a3e03bc1368 ("KVM: s390: index kvm->arch.idle_mask by vcpu_idx") >> This basically removes the kick_mask parts that were introduced with >> kernel 5.0 and fixes up the location of the idle_mask to the older >> place. >> >> FWIW, it might be a good idea to also backport >> 8750e72a79dd ("KVM: remember position in kvm->vcpus array") to avoid >> a performance regression for large guests (many vCPUs) when this patch >> is applied. >> @Paolo Bonzini, would you be ok with 8750e72a79dd in older stable releases? > > Sure, I suppose you're going to send a separate backport that I can ack. It does seem to apply when cherry-picked, but I can send it as a patch if you and Greg prefer it that way. ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index 2021-09-21 8:46 ` Christian Borntraeger @ 2021-09-21 13:04 ` Paolo Bonzini 0 siblings, 0 replies; 8+ messages in thread From: Paolo Bonzini @ 2021-09-21 13:04 UTC (permalink / raw) To: Christian Borntraeger, stable Cc: gregkh, KVM, Cornelia Huck, Janosch Frank, David Hildenbrand, linux-s390, Thomas Huth, Claudio Imbrenda, Radim Krčmář, Nitesh Narayan Lal, Halil Pasic On 21/09/21 10:46, Christian Borntraeger wrote: >>> >> >> Sure, I suppose you're going to send a separate backport that I can >> ack. > > It does seem to apply when cherry-picked, but I can send it as a > patch if you and Greg prefer it that way. Yes, please do! Thanks, Paolo ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2021-09-21 13:04 UTC | newest] Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-09-20 15:06 [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index Christian Borntraeger 2021-09-20 15:06 ` [PATCH 1/1] KVM: s390: index kvm->arch.idle_mask by vcpu_idx Christian Borntraeger 2021-09-21 2:43 ` Halil Pasic 2021-09-20 15:24 ` [PATCH 0/1] KVM: s390: backport for stable of "KVM: s390: index Greg KH 2021-09-20 15:30 ` Christian Borntraeger 2021-09-20 18:05 ` Paolo Bonzini 2021-09-21 8:46 ` Christian Borntraeger 2021-09-21 13:04 ` Paolo Bonzini
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.