From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Mueller Subject: Re: [PATCH v6 11/13] KVM: s390: add functions to (un)register GISC with GISA Date: Mon, 28 Jan 2019 17:04:10 +0100 Message-ID: <863b0635-ff88-10ca-4541-a1f27d12c758@linux.ibm.com> References: <20190124125939.130763-1-mimu@linux.ibm.com> <20190124125939.130763-12-mimu@linux.ibm.com> Reply-To: mimu@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: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: pmorel@linux.ibm.com, 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 28.01.19 16:45, Pierre Morel wrote: > 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. I dropped that in both routines. > > > >> +    } >> +    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 > Cheers, Michael