KVM: s390: interface for suppressible I/O adapters

In order to properly implement adapter-interruption suppression, we
need a way for userspace to specify which adapters are subject to
suppression. Let's convert the existing (and unused) 'pad' field into
a 'flags' field and define a flag value for suppressible adapters.

Besides, add documentation for the interface.

Signed-off-by: Fei Li <sherrylf@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

4 files changed, 15 insertions, 4 deletions

diff --git a/Documentation/virtual/kvm/devices/s390_flic.txt b/Documentation/virtual/kvm/devices/s390_flic.txt
index 6b0e115301c8..e8ee3b6edb05 100644
--- a/Documentation/virtual/kvm/devices/s390_flic.txt
+++ b/Documentation/virtual/kvm/devices/s390_flic.txt
@@ -64,12 +64,18 @@ struct kvm_s390_io_adapter {
         __u8 isc;
         __u8 maskable;
         __u8 swap;
-        __u8 pad;
+        __u8 flags;
 };
 
    id contains the unique id for the adapter, isc the I/O interruption subclass
-   to use, maskable whether this adapter may be masked (interrupts turned off)
-   and swap whether the indicators need to be byte swapped.
+   to use, maskable whether this adapter may be masked (interrupts turned off),
+   swap whether the indicators need to be byte swapped, and flags contains
+   further characteristics of the adapter.
+   Currently defined values for 'flags' are:
+   - KVM_S390_ADAPTER_SUPPRESSIBLE: adapter is subject to AIS
+     (adapter-interrupt-suppression) facility. This flag only has an effect if
+     the AIS capability is enabled.
+   Unknown flag values are ignored.
 
 
   KVM_DEV_FLIC_ADAPTER_MODIFY
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 1af090d93bf5..499c72c2280d 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -621,6 +621,7 @@ struct s390_io_adapter {
         bool maskable;
         bool masked;
         bool swap;
+        bool suppressible;
         struct rw_semaphore maps_lock;
         struct list_head maps;
         atomic_t nr_maps;
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index 5bd23cfd9ae5..5fa144d1df0a 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -41,9 +41,11 @@ struct kvm_s390_io_adapter {
         __u8 isc;
         __u8 maskable;
         __u8 swap;
-        __u8 pad;
+        __u8 flags;
 };
 
+#define KVM_S390_ADAPTER_SUPPRESSIBLE 0x01
+
 #define KVM_S390_IO_ADAPTER_MASK 1
 #define KVM_S390_IO_ADAPTER_MAP 2
 #define KVM_S390_IO_ADAPTER_UNMAP 3
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 311eef0df855..dba51ad62570 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -1997,6 +1997,8 @@ static int register_io_adapter(struct kvm_device *dev,
         adapter->maskable = adapter_info.maskable;
         adapter->masked = false;
         adapter->swap = adapter_info.swap;
+        adapter->suppressible = (adapter_info.flags) &
+                                KVM_S390_ADAPTER_SUPPRESSIBLE;
         dev->kvm->arch.adapters[adapter->id] = adapter;
 
         return 0;