diff --git a/Documentation/arm64/sme.rst b/Documentation/arm64/sme.rst
index 16d2db4c2e2e..5f7eabee4853 100644
--- a/Documentation/arm64/sme.rst
+++ b/Documentation/arm64/sme.rst
@@ -18,14 +18,19 @@ model features for SME is included in Appendix A.
 1.  General
 -----------
 
-* PSTATE.SM, PSTATE.ZA, the streaming mode vector length, the ZA
-  register state and TPIDR2_EL0 are tracked per thread.
+* PSTATE.SM, PSTATE.ZA, the streaming mode vector length, the ZA and (when
+  present) ZT0 register state and TPIDR2_EL0 are tracked per thread.
 
 * The presence of SME is reported to userspace via HWCAP2_SME in the aux vector
   AT_HWCAP2 entry.  Presence of this flag implies the presence of the SME
   instructions and registers, and the Linux-specific system interfaces
   described in this document.  SME is reported in /proc/cpuinfo as "sme".
 
+* The presence of SME2 is reported to userspace via HWCAP2_SME in the
+  aux vector AT_HWCAP2 entry.  Presence of this flag implies the presence of
+  the SME2 instructions and ZT0, and the Linux-specific system interfaces
+  described in this document.  SME2 is reported in /proc/cpuinfo as "sme2".
+
 * Support for the execution of SME instructions in userspace can also be
   detected by reading the CPU ID register ID_AA64PFR1_EL1 using an MRS
   instruction, and checking that the value of the SME field is nonzero. [3]
@@ -44,6 +49,7 @@ model features for SME is included in Appendix A.
 	HWCAP2_SME_B16F32
 	HWCAP2_SME_F32F32
 	HWCAP2_SME_FA64
+        HWCAP2_SME2
 
   This list may be extended over time as the SME architecture evolves.
 
@@ -52,8 +58,8 @@ model features for SME is included in Appendix A.
   cpu-feature-registers.txt for details.
 
 * Debuggers should restrict themselves to interacting with the target via the
-  NT_ARM_SVE, NT_ARM_SSVE and NT_ARM_ZA regsets.  The recommended way
-  of detecting support for these regsets is to connect to a target process
+  NT_ARM_SVE, NT_ARM_SSVE, NT_ARM_ZA and NT_ARM_ZT regsets.  The recommended
+  way of detecting support for these regsets is to connect to a target process
   first and then attempt a
 
 	ptrace(PTRACE_GETREGSET, pid, NT_ARM_<regset>, &iov).
@@ -89,13 +95,13 @@ be zeroed.
 -------------------------
 
 * On syscall PSTATE.ZA is preserved, if PSTATE.ZA==1 then the contents of the
-  ZA matrix are preserved.
+  ZA matrix and ZT0 (if present) are preserved.
 
 * On syscall PSTATE.SM will be cleared and the SVE registers will be handled
   as per the standard SVE ABI.
 
-* Neither the SVE registers nor ZA are used to pass arguments to or receive
-  results from any syscall.
+* None of the SVE registers, ZA or ZT0 are used to pass arguments to
+  or receive results from any syscall.
 
 * On process creation (eg, clone()) the newly created process will have
   PSTATE.SM cleared.
@@ -134,6 +140,14 @@ be zeroed.
   __reserved[] referencing this space.  za_context is then written in the
   extra space.  Refer to [1] for further details about this mechanism.
 
+* If ZT is supported and PSTATE.ZA==1 then a signal frame record for ZT will
+  be generated.
+
+* The signal record for ZT has magic ZT_MAGIC (0x73d4e827) and consists of a
+  standard signal frame header followed by a struct zt_context specifying
+  the number of ZT registers supported by the system, then zt_contxt.nregs
+  blocks of 64 bytes of data per register.
+
 
 5.  Signal return
 -----------------
@@ -151,6 +165,9 @@ When returning from a signal handler:
   the signal frame does not match the current vector length, the signal return
   attempt is treated as illegal, resulting in a forced SIGSEGV.
 
+* If ZT is not supported or PSTATE.ZA==0 then it is illegal to have a
+  signal frame record for ZT, resulting in a forced SIGSEGV.
+
 
 6.  prctl extensions
 --------------------
@@ -214,8 +231,8 @@ prctl(PR_SME_SET_VL, unsigned long arg)
       vector length that will be applied at the next execve() by the calling
       thread.
 
-    * Changing the vector length causes all of ZA, P0..P15, FFR and all bits of
-      Z0..Z31 except for Z0 bits [127:0] .. Z31 bits [127:0] to become
+    * Changing the vector length causes all of ZA, ZT, P0..P15, FFR and all
+      bits of Z0..Z31 except for Z0 bits [127:0] .. Z31 bits [127:0] to become
       unspecified, including both streaming and non-streaming SVE state.
       Calling PR_SME_SET_VL with vl equal to the thread's current vector
       length, or calling PR_SME_SET_VL with the PR_SVE_SET_VL_ONEXEC flag,
@@ -317,6 +334,15 @@ The regset data starts with struct user_za_header, containing:
 
 * The effect of writing a partial, incomplete payload is unspecified.
 
+* A new regset NT_ARM_ZT is defined for for access to ZT state via
+  PTRACE_GETREGSET and PTRACE_SETREGSET.
+
+* The NT_ARM_ZT regset consists of a single 512 bit register.
+
+* When PSTATE.ZA==0 reads of NT_ARM_ZT will report all bits of ZT as 0.
+
+* Writes to NT_ARM_ZT will set PSTATE.ZA to 1.
+
 
 8.  ELF coredump extensions
 ---------------------------
@@ -331,6 +357,11 @@ The regset data starts with struct user_za_header, containing:
   been read if a PTRACE_GETREGSET of NT_ARM_ZA were executed for each thread
   when the coredump was generated.
 
+* A NT_ARM_ZT note will be added to each coredump for each thread of the
+  dumped process.  The contents will be equivalent to the data that would have
+  been read if a PTRACE_GETREGSET of NT_ARM_ZT were executed for each thread
+  when the coredump was generated.
+
 * The NT_ARM_TLS note will be extended to two registers, the second register
   will contain TPIDR2_EL0 on systems that support SME and will be read as
   zero with writes ignored otherwise.
@@ -406,6 +437,9 @@ In A64 state, SME adds the following:
   For best system performance it is strongly encouraged for software to enable
   ZA only when it is actively being used.
 
+* A new ZT0 register is introduced when SME2 is present. This is a 512 bit
+  register which is accessible PSTATE.ZA is set, as ZA itself is.
+
 * Two new 1 bit fields in PSTATE which may be controlled via the SMSTART and
   SMSTOP instructions or by access to the SVCR system register:
 
