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Subject[PATCH v5 10/15] KVM: s390: add functions to (un)register GISC with GISA
Date
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@linux.ibm.com>
---
arch/s390/include/asm/kvm_host.h | 9 ++++++
arch/s390/kvm/interrupt.c | 66 ++++++++++++++++++++++++++++++++++++++++
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 {
u8 reserved03[11];
u32 airq_count;
} g1;
+ struct {
+ u64 word[4];
+ } u64;
};
};

@@ -849,6 +852,9 @@ struct kvm_arch{
DECLARE_BITMAP(cpu_feat, KVM_S390_VM_CPU_FEAT_NR_BITS);
struct kvm_s390_gisa *gisa;
int gib_in_use;
+ u8 iam;
+ u32 iam_ref_count[MAX_ISC + 1];
+ spinlock_t iam_ref_lock;
};

#define KVM_HVA_ERR_BAD (-1UL)
@@ -882,6 +888,9 @@ 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 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)
*/
#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)
+{
+ u64 word0, _word0;
+
+ do {
+ word0 = READ_ONCE(gisa->u64.word[0]);
+ /* If the GISA is in the alert list, do nothing. */
+ if ((u64)gisa != word0 >> 32)
+ return -EBUSY;
+ /*
+ * Try to set the IAM or loop, if the IPM has changed
+ * or the GISA has been inserted into the alert list.
+ */
+ _word0 = (word0 & ~0xffUL) | iam;
+ } while (cmpxchg(&gisa->u64.word[0], word0, _word0) != _word0);
+
+ return 0;
+}
+
static inline void set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
{
set_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
@@ -2917,6 +2936,8 @@ void kvm_s390_gisa_init(struct kvm *kvm)
if (!css_general_characteristics.aiv)
return;
kvm->arch.gisa = &kvm->arch.sie_page2->gisa;
+ kvm->arch.iam = 0;
+ spin_lock_init(&kvm->arch.iam_ref_lock);
nullify_gisa(kvm->arch.gisa);
kvm->arch.gib_in_use = !!gib;
VM_EVENT(kvm, 3, "gisa 0x%pK initialized", kvm->arch.gisa);
@@ -2929,6 +2950,51 @@ void kvm_s390_gisa_destroy(struct kvm *kvm)
kvm->arch.gisa = NULL;
}

+int kvm_s390_gisc_register(struct kvm *kvm, u32 gisc)
+{
+ if (!kvm->arch.gib_in_use)
+ return -ENODEV;
+ if (gisc > MAX_ISC)
+ return -ERANGE;
+
+ spin_lock(&kvm->arch.iam_ref_lock);
+ if (kvm->arch.iam_ref_count[gisc] == 0)
+ kvm->arch.iam |= 0x80 >> gisc;
+ kvm->arch.iam_ref_count[gisc]++;
+ if (kvm->arch.iam_ref_count[gisc] == 1)
+ set_iam(kvm->arch.gisa, kvm->arch.iam);
+ spin_unlock(&kvm->arch.iam_ref_lock);
+
+ return gib->nisc;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_gisc_register);
+
+int kvm_s390_gisc_unregister(struct kvm *kvm, u32 gisc)
+{
+ int rc = 0;
+
+ if (!kvm->arch.gib_in_use)
+ return -ENODEV;
+ if (gisc > MAX_ISC)
+ return -ERANGE;
+
+ spin_lock(&kvm->arch.iam_ref_lock);
+ if (kvm->arch.iam_ref_count[gisc] == 0) {
+ rc = -EINVAL;
+ goto out;
+ }
+ kvm->arch.iam_ref_count[gisc]--;
+ if (kvm->arch.iam_ref_count[gisc] == 0) {
+ kvm->arch.iam &= ~(0x80 >> gisc);
+ set_iam(kvm->arch.gisa, kvm->arch.iam);
+ }
+out:
+ spin_unlock(&kvm->arch.iam_ref_lock);
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_gisc_unregister);
+
void kvm_s390_gib_destroy(void)
{
if (!gib)
--
2.13.4
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