Merge tag 'kvm-s390-next-6.3-1' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

* Two more V!=R patches
* The last part of the cmpxchg patches
* A few fixes

2 files changed, 41 insertions, 9 deletions

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 1b1f721e3fd969..62de0768d6aa59 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -3736,7 +3736,7 @@ The fields in each entry are defined as follows:
 :Parameters: struct kvm_s390_mem_op (in)
 :Returns: = 0 on success,
           < 0 on generic error (e.g. -EFAULT or -ENOMEM),
-          > 0 if an exception occurred while walking the page tables
+          16 bit program exception code if the access causes such an exception
 
 Read or write data from/to the VM's memory.
 The KVM_CAP_S390_MEM_OP_EXTENSION capability specifies what functionality is
@@ -3754,6 +3754,8 @@ Parameters are specified via the following structure::
 		struct {
 			__u8 ar;	/* the access register number */
 			__u8 key;	/* access key, ignored if flag unset */
+			__u8 pad1[6];	/* ignored */
+			__u64 old_addr;	/* ignored if flag unset */
 		};
 		__u32 sida_offset; /* offset into the sida */
 		__u8 reserved[32]; /* ignored */
@@ -3781,6 +3783,7 @@ Possible operations are:
   * ``KVM_S390_MEMOP_ABSOLUTE_WRITE``
   * ``KVM_S390_MEMOP_SIDA_READ``
   * ``KVM_S390_MEMOP_SIDA_WRITE``
+  * ``KVM_S390_MEMOP_ABSOLUTE_CMPXCHG``
 
 Logical read/write:
 ^^^^^^^^^^^^^^^^^^^
@@ -3829,7 +3832,7 @@ the checks required for storage key protection as one operation (as opposed to
 user space getting the storage keys, performing the checks, and accessing
 memory thereafter, which could lead to a delay between check and access).
 Absolute accesses are permitted for the VM ioctl if KVM_CAP_S390_MEM_OP_EXTENSION
-is > 0.
+has the KVM_S390_MEMOP_EXTENSION_CAP_BASE bit set.
 Currently absolute accesses are not permitted for VCPU ioctls.
 Absolute accesses are permitted for non-protected guests only.
 
@@ -3837,7 +3840,26 @@ Supported flags:
   * ``KVM_S390_MEMOP_F_CHECK_ONLY``
   * ``KVM_S390_MEMOP_F_SKEY_PROTECTION``
 
-The semantics of the flags are as for logical accesses.
+The semantics of the flags common with logical accesses are as for logical
+accesses.
+
+Absolute cmpxchg:
+^^^^^^^^^^^^^^^^^
+
+Perform cmpxchg on absolute guest memory. Intended for use with the
+KVM_S390_MEMOP_F_SKEY_PROTECTION flag.
+Instead of doing an unconditional write, the access occurs only if the target
+location contains the value pointed to by "old_addr".
+This is performed as an atomic cmpxchg with the length specified by the "size"
+parameter. "size" must be a power of two up to and including 16.
+If the exchange did not take place because the target value doesn't match the
+old value, the value "old_addr" points to is replaced by the target value.
+User space can tell if an exchange took place by checking if this replacement
+occurred. The cmpxchg op is permitted for the VM ioctl if
+KVM_CAP_S390_MEM_OP_EXTENSION has flag KVM_S390_MEMOP_EXTENSION_CAP_CMPXCHG set.
+
+Supported flags:
+  * ``KVM_S390_MEMOP_F_SKEY_PROTECTION``
 
 SIDA read/write:
 ^^^^^^^^^^^^^^^^
@@ -4457,6 +4479,18 @@ not holding a previously reported uncorrected error).
 :Parameters: struct kvm_s390_cmma_log (in, out)
 :Returns: 0 on success, a negative value on error
 
+Errors:
+
+  ======     =============================================================
+  ENOMEM     not enough memory can be allocated to complete the task
+  ENXIO      if CMMA is not enabled
+  EINVAL     if KVM_S390_CMMA_PEEK is not set but migration mode was not enabled
+  EINVAL     if KVM_S390_CMMA_PEEK is not set but dirty tracking has been
+             disabled (and thus migration mode was automatically disabled)
+  EFAULT     if the userspace address is invalid or if no page table is
+             present for the addresses (e.g. when using hugepages).
+  ======     =============================================================
+
 This ioctl is used to get the values of the CMMA bits on the s390
 architecture. It is meant to be used in two scenarios:
 
@@ -4537,12 +4571,6 @@ mask is unused.
 
 values points to the userspace buffer where the result will be stored.
 
-This ioctl can fail with -ENOMEM if not enough memory can be allocated to
-complete the task, with -ENXIO if CMMA is not enabled, with -EINVAL if
-KVM_S390_CMMA_PEEK is not set but migration mode was not enabled, with
--EFAULT if the userspace address is invalid or if no page table is
-present for the addresses (e.g. when using hugepages).
-
 4.108 KVM_S390_SET_CMMA_BITS
 ----------------------------
 
diff --git a/Documentation/virt/kvm/devices/vm.rst b/Documentation/virt/kvm/devices/vm.rst
index 60acc39e0e937c..147efec626e521 100644
--- a/Documentation/virt/kvm/devices/vm.rst
+++ b/Documentation/virt/kvm/devices/vm.rst
@@ -302,6 +302,10 @@ Allows userspace to start migration mode, needed for PGSTE migration.
 Setting this attribute when migration mode is already active will have
 no effects.
 
+Dirty tracking must be enabled on all memslots, else -EINVAL is returned. When
+dirty tracking is disabled on any memslot, migration mode is automatically
+stopped.
+
 :Parameters: none
 :Returns:   -ENOMEM if there is not enough free memory to start migration mode;
 	    -EINVAL if the state of the VM is invalid (e.g. no memory defined);