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

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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>
---
  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;

In kvm_s390_gisa_clear() you do:

+        nullify_gisa(kvm->arch.gisa);
+        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 Böblingen - Germany




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