Re: [PATCH v5 10/15] KVM: s390: add functions to (un)register GISC with GISA

[Pierre Morel]

On 02/01/2019 18:29, Pierre Morel wrote:
> On 19/12/2018 20:17, Michael Mueller wrote:
> > Add the IAM (Interruption Alert Mask) to the architecture specific
> > kvm struct. This mask in the GISA is used to define for which ISC
> > a GIB alert can 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 <mimu@xxxxxxxxxxxxx>
> > ---
> > Â arch/s390/include/asm/kvm_host.h |Â 9 ++++++
> > Â arch/s390/kvm/interrupt.cÂÂÂÂÂÂÂ | 66 
> > ++++++++++++++++++++++++++++++++++++++++
> > Â 2 files changed, 75 insertions(+)
> >
> > diff --git a/arch/s390/include/asm/kvm_host.h 
> > b/arch/s390/include/asm/kvm_host.h
> > index 0deba3ae8bc7..2c1259da3636 100644
> > --- a/arch/s390/include/asm/kvm_host.h
> > +++ b/arch/s390/include/asm/kvm_host.h
> > @@ -782,6 +782,9 @@ struct kvm_s390_gisa {
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂ u8Â reserved03[11];
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂ u32 airq_count;
> > ÂÂÂÂÂÂÂÂÂ } g1;
> > +ÂÂÂÂÂÂÂ struct {
> > +ÂÂÂÂÂÂÂÂÂÂÂ u64 word[4];
> > +ÂÂÂÂÂÂÂ } u64;
> > ÂÂÂÂÂ };
> > Â };
> > @@ -849,6 +852,9 @@ struct kvm_arch{
> > ÂÂÂÂÂ DECLARE_BITMAP(cpu_feat, KVM_S390_VM_CPU_FEAT_NR_BITS);
> > ÂÂÂÂÂ struct kvm_s390_gisa *gisa;
> > ÂÂÂÂÂ int gib_in_use;
> > +ÂÂÂ u8 iam;
> > +ÂÂÂ u32 iam_ref_count[MAX_ISC + 1];
> > +ÂÂÂ spinlock_t iam_ref_lock;
> > Â };
> > Â #define KVM_HVA_ERR_BADÂÂÂÂÂÂÂ (-1UL)
> > @@ -882,6 +888,9 @@ void kvm_arch_crypto_set_masks(struct kvm *kvm, 
> > unsigned long *apm,
> > Â extern int sie64a(struct kvm_s390_sie_block *, u64 *);
> > Â 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);
> > +
> > Â static inline void kvm_arch_hardware_disable(void) {}
> > Â static inline void kvm_arch_check_processor_compat(void *rtn) {}
> > Â 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 5a54360cecfe..1cc3ad2e6c7e 100644
> > --- a/arch/s390/kvm/interrupt.c
> > +++ b/arch/s390/kvm/interrupt.c
> > @@ -229,6 +229,25 @@ static inline u8 int_word_to_isc(u32 int_word)
> > ÂÂ */
> > Â #define IPM_BIT_OFFSET (offsetof(struct kvm_s390_gisa, ipm) * 
> > BITS_PER_BYTE)
> > +static inline int set_iam(struct kvm_s390_gisa *gisa, u8 iam)
> > +{
> > +ÂÂÂ u64 word0, _word0;
> > +
> > +ÂÂÂ do {
> > +ÂÂÂÂÂÂÂ word0 = READ_ONCE(gisa->u64.word[0]);
> > +ÂÂÂÂÂÂÂ /* If the GISA is in the alert list, do nothing. */
> > +ÂÂÂÂÂÂÂ if ((u64)gisa != word0 >> 32)
> > +ÂÂÂÂÂÂÂÂÂÂÂ return -EBUSY;
>
> In kvm_s390_gisa_clear() you do:
>
> +ÂÂÂÂÂÂÂ nullify_gisa(kvm->arch.gisa);
> +ÂÂÂÂÂÂÂ set_iam(kvm->arch.gisa, kvm->arch.iam);
>
> IIUC this call to set_iam() will always fail.

Hum, sorry, I oversaw a patch which corrected this problem.
Sorry for the noise.
(I should have seen it since I copied the right lines!)

Regards,
Pierre

--
Pierre Morel
Linux/KVM/QEMU in BÃblingen - Germany