From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Morel Subject: Re: [PATCH v6 11/13] KVM: s390: add functions to (un)register GISC with GISA Date: Mon, 28 Jan 2019 16:45:51 +0100 Message-ID: References: <20190124125939.130763-1-mimu@linux.ibm.com> <20190124125939.130763-12-mimu@linux.ibm.com> Reply-To: pmorel@linux.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190124125939.130763-12-mimu@linux.ibm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Michael Mueller , KVM Mailing List Cc: Linux-S390 Mailing List , linux-kernel@vger.kernel.org, Martin Schwidefsky , Heiko Carstens , Christian Borntraeger , Janosch Frank , David Hildenbrand , Cornelia Huck , Halil Pasic List-ID: On 24/01/2019 13:59, Michael Mueller wrote: > Add the Interruption Alert Mask (IAM) to the architecture specific > kvm struct. This mask in the GISA is used to define for which ISC > a GIB alert will be issued. > > The functions kvm_s390_gisc_register() and kvm_s390_gisc_unregister() > are used to (un)register a GISC (guest ISC) with a virtual machine and > its GISA. > > Upon successful completion, kvm_s390_gisc_register() returns the > ISC to be used for GIB alert interruptions. A negative return code > indicates an error during registration. > > Theses functions will be used by other adapter types like AP and PCI to > request pass-through interruption support. > > Signed-off-by: Michael Mueller > --- > arch/s390/include/asm/kvm_host.h | 13 +++++ > arch/s390/kvm/interrupt.c | 117 +++++++++++++++++++++++++++++++++++++++ > 2 files changed, 130 insertions(+) > > diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h > index 7077762ab460..2cfff617cb21 100644 > --- a/arch/s390/include/asm/kvm_host.h > +++ b/arch/s390/include/asm/kvm_host.h > @@ -781,6 +781,9 @@ struct kvm_s390_gisa { > u8 reserved03[11]; > u32 airq_count; > } g1; > + struct { > + u64 word[4]; > + } u64; > }; > }; > > @@ -813,8 +816,15 @@ struct kvm_s390_vsie { > struct page *pages[KVM_MAX_VCPUS]; > }; > > +struct kvm_s390_gisa_iam { > + u8 mask; > + spinlock_t ref_lock; > + u32 ref_count[MAX_ISC + 1]; > +}; > + > struct kvm_s390_gisa_interrupt { > struct kvm_s390_gisa *origin; > + struct kvm_s390_gisa_iam alert; > }; > > struct kvm_arch{ > @@ -885,6 +895,9 @@ void kvm_arch_crypto_set_masks(struct kvm *kvm, unsigned long *apm, > extern int sie64a(struct kvm_s390_sie_block *, u64 *); > extern char sie_exit; > > +extern int kvm_s390_gisc_register(struct kvm *kvm, u32 gisc); > +extern int kvm_s390_gisc_unregister(struct kvm *kvm, u32 gisc); > + > static inline void kvm_arch_hardware_disable(void) {} > static inline void kvm_arch_check_processor_compat(void *rtn) {} > static inline void kvm_arch_sync_events(struct kvm *kvm) {} > diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c > index 5efcd9e2cf8f..6bc9dab6d352 100644 > --- a/arch/s390/kvm/interrupt.c > +++ b/arch/s390/kvm/interrupt.c > @@ -222,6 +222,33 @@ static inline u8 int_word_to_isc(u32 int_word) > */ > #define IPM_BIT_OFFSET (offsetof(struct kvm_s390_gisa, ipm) * BITS_PER_BYTE) > > +/** > + * gisa_set_iam - change the GISA interruption alert mask > + * > + * @gisa: gisa to operate on > + * @iam: new IAM value to use > + * > + * Change the IAM atomically with the next alert address and the IPM > + * of the GISA if the GISA is not part of the GIB alert list. All three > + * fields are located in the first long word of the GISA. > + * > + * Returns: 0 on success > + * -EBUSY in case the gisa is part of the alert list > + */ > +static inline int gisa_set_iam(struct kvm_s390_gisa *gisa, u8 iam) > +{ > + u64 word, _word; > + > + do { > + word = READ_ONCE(gisa->u64.word[0]); > + if ((u64)gisa != word >> 32) > + return -EBUSY; > + _word = (word & ~0xffUL) | iam; > + } while (cmpxchg(&gisa->u64.word[0], word, _word) != word); > + > + return 0; > +} > + > static inline void gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc) > { > set_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa); > @@ -2911,6 +2938,8 @@ void kvm_s390_gisa_init(struct kvm *kvm) > if (!css_general_characteristics.aiv) > return; > gi->origin = &kvm->arch.sie_page2->gisa; > + gi->alert.mask = 0; > + spin_lock_init(&gi->alert.ref_lock); > kvm_s390_gisa_clear(kvm); > VM_EVENT(kvm, 3, "gisa 0x%pK initialized", gi->origin); > } > @@ -2920,6 +2949,94 @@ void kvm_s390_gisa_destroy(struct kvm *kvm) > kvm->arch.gisa_int.origin = NULL; > } > > +/** > + * kvm_s390_gisc_register - register a guest ISC > + * > + * @kvm: the kernel vm to work with > + * @gisc: the guest interruption sub class to register > + * > + * The function extends the vm specific alert mask to use. > + * The effectve IAM mask in the GISA is updated as well > + * in case the GISA is not part of the GIB alert list. > + * It will be updated latest when the IAM gets restored > + * by gisa_get_ipm_or_restore_iam(). > + * > + * Returns: the nonspecific ISC (NISC) the gib alert mechanism > + * has registered with the channel subsystem. > + * -ENODEV in case the vm uses no GISA > + * -ERANGE in case the guest ISC is invalid > + */ > +int kvm_s390_gisc_register(struct kvm *kvm, u32 gisc) > +{ > + struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int; > + u8 alert_mask; > + > + if (!gi->origin) > + return -ENODEV; > + if (gisc > MAX_ISC) > + return -ERANGE; > + > + spin_lock(&gi->alert.ref_lock); > + if (gi->alert.ref_count[gisc] == 0) { > + alert_mask = gi->alert.mask | 0x80 >> gisc; > + WRITE_ONCE(gi->alert.mask, alert_mask); not sure WRITE_ONCE is useful. > + } > + gi->alert.ref_count[gisc]++; > + if (gi->alert.ref_count[gisc] == 1) > + gisa_set_iam(gi->origin, alert_mask); This will trigger a GAL interrupt on first AP interrupt in all cases. However setting the iam here is simple and the price is not so high. so... without the WRITE_ONCE in register and in unregister: Acked-by: Pierre Morel Pierre -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany