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authorPaolo Bonzini <pbonzini@redhat.com>2023-02-15 20:35:26 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2023-02-15 20:35:26 +0300
commite4922088f8e90ea163281ba8e69b98f34a7a1b83 (patch)
tree1db574412a5365f285754dd0364d249581535ad8 /Documentation/virt
parent33436335e93a1788a58443fc99c5ab320ce4b9d9 (diff)
parent5fc5b94a273655128159186c87662105db8afeb5 (diff)
downloadlinux-e4922088f8e90ea163281ba8e69b98f34a7a1b83.tar.xz
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
Diffstat (limited to 'Documentation/virt')
-rw-r--r--Documentation/virt/kvm/api.rst46
-rw-r--r--Documentation/virt/kvm/devices/vm.rst4
2 files changed, 41 insertions, 9 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 1b1f721e3fd9..62de0768d6aa 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 60acc39e0e93..147efec626e5 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);