[RFC PATCH v3 1/2] Capability/IOCTL/Documentation

From: Eric Farman <farman@linux.ibm.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>,
	Janosch Frank <frankja@linux.ibm.com>,
	David Hildenbrand <david@redhat.com>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>,
	Thomas Huth <thuth@redhat.com>
Cc: Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	kvm@vger.kernel.org, linux-s390@vger.kernel.org,
	Eric Farman <farman@linux.ibm.com>
Subject: [RFC PATCH v3 1/2] Capability/IOCTL/Documentation
Date: Wed, 10 Nov 2021 21:33:21 +0100	[thread overview]
Message-ID: <20211110203322.1374925-2-farman@linux.ibm.com> (raw)
In-Reply-To: <20211110203322.1374925-1-farman@linux.ibm.com>

(This should be squashed with the next patch; it's just broken
out for ease-of-future rebase.)

Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
 Documentation/virt/kvm/api.rst | 39 ++++++++++++++++++++++++++++++++++
 include/uapi/linux/kvm.h       |  5 +++++
 2 files changed, 44 insertions(+)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index a6729c8cf063..c1d0cae51f03 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -5317,6 +5317,30 @@ the trailing ``'\0'``, is indicated by ``name_size`` in the header.
 The Stats Data block contains an array of 64-bit values in the same order
 as the descriptors in Descriptors block.
 
+4.134 KVM_S390_VCPU_RESET_SIGP_BUSY
+-----------------------------------
+
+:Capability: KVM_CAP_S390_USER_SIGP_BUSY
+:Architectures: s390
+:Type: vcpu ioctl
+:Parameters: none
+:Returns: 0
+
+This ioctl resets the VCPU's indicator that it is busy processing a SIGP
+order, and is thus available for additional SIGP orders.
+
+4.135 KVM_S390_VCPU_SET_SIGP_BUSY
+---------------------------------
+
+:Capability: KVM_CAP_S390_USER_SIGP_BUSY
+:Architectures: s390
+:Type: vcpu ioctl
+:Parameters: none
+:Returns: 0, or -EBUSY if VCPU is already busy
+
+This ioctl sets the VCPU's indicator that it is busy processing a SIGP
+order, and is thus unavailable for additional SIGP orders.
+
 5. The kvm_run structure
 ========================
 
@@ -6706,6 +6730,21 @@ MAP_SHARED mmap will result in an -EINVAL return.
 When enabled the VMM may make use of the ``KVM_ARM_MTE_COPY_TAGS`` ioctl to
 perform a bulk copy of tags to/from the guest.
 
+7.29 KVM_CAP_S390_USER_SIGP_BUSY
+--------------------------------
+
+:Architectures: s390
+:Parameters: none
+
+This capability indicates that KVM should indicate when a SIGP order has been
+sent to userspace for a particular vcpu, and return CC2 (BUSY) to any further
+SIGP order directed at the same vcpu even for those orders that are handled
+within the kernel.
+
+This capability is dependent on KVM_CAP_S390_USER_SIGP. If this capability
+is not enabled, SIGP orders handled by the kernel may not indicate whether a
+vcpu is currently processing another SIGP order.
+
 8. Other capabilities.
 ======================
 
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index a067410ebea5..a00d5e226137 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1112,6 +1112,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_BINARY_STATS_FD 203
 #define KVM_CAP_EXIT_ON_EMULATION_FAILURE 204
 #define KVM_CAP_ARM_MTE 205
+#define KVM_CAP_S390_USER_SIGP_BUSY 206
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -2007,4 +2008,8 @@ struct kvm_stats_desc {
 
 #define KVM_GET_STATS_FD  _IO(KVMIO,  0xce)
 
+/* Available with KVM_CAP_S390_USER_SIGP_BUSY */
+#define KVM_S390_VCPU_RESET_SIGP_BUSY	_IO(KVMIO, 0xcf)
+#define KVM_S390_VCPU_SET_SIGP_BUSY	_IO(KVMIO, 0xd0)
+
 #endif /* __LINUX_KVM_H */
-- 
2.25.1

