doc: add v3.0.1 release notes

Signed-off-by: David B. Kinder <david.b.kinder@intel.com>

doc/release_notes/release_notes_3.0.1.rst

@@ -0,0 +1,54 @@
+.. _release_notes_3.0.1:
+
+ACRN v3.0.1 (Jul 2022)
+######################
+
+We are pleased to announce the release of the Project ACRN hypervisor
+version 3.0.1 with hot fixes to the v3.0 release.
+
+ACRN is a flexible, lightweight reference hypervisor that is built with
+real-time and safety-criticality in mind. It is optimized to streamline
+embedded development through an open-source platform. See the
+:ref:`introduction` introduction for more information.
+
+All project ACRN source code is maintained in the
+https://github.com/projectacrn/acrn-hypervisor repository and includes
+folders for the ACRN hypervisor, the ACRN device model, tools, and
+documentation. You can download this source code either as a zip or
+tar.gz file (see the `ACRN v3.0.1 GitHub release page
+<https://github.com/projectacrn/acrn-hypervisor/releases/tag/v3.0.1>`_) or
+use Git ``clone`` and ``checkout`` commands::
+
+   git clone https://github.com/projectacrn/acrn-hypervisor
+   cd acrn-hypervisor
+   git checkout v3.0.1
+
+The project's online technical documentation is also tagged to
+correspond with a specific release: generated v3.0 documents can be
+found at https://projectacrn.github.io/3.0/.  Documentation for the
+latest development branch is found at https://projectacrn.github.io/latest/.
+
+ACRN v3.0.1 requires Ubuntu 20.04 (as does v3.0).  Follow the instructions in the
+:ref:`gsg` to get started with ACRN.
+
+
+What's New in v3.0.1
+********************
+
+Mitigation for Return Stack Buffer Underflow security vulnerability
+  For platforms that supports RRSBA (Restricted Return Stack Buffer
+  Alternate), using retpoline may not be sufficient to guard against branch
+  history injection or intra-mode branch target injection. RRSBA must
+  be disabled to prevent CPUs from using alternate predictors for RETs.
+  (Addresses security issue tracked by CVE-2022-29901 and CVE-2022-28693.)
+
+ACRN shell commands added for real-time performance profiling
+  ACRN shell commands were added to sample vmexit data per virtual CPU to
+  facilitate real-time performance profiling:
+
+  * ``vmexit clear``: clears current vmexit buffer
+  * ``vmexit [vm_id]``: outputs vmexit info per vCPU
+  * ``vmexit enable | disable``: enabled by default
+
+
+See :ref:`release_notes_3.0` for additional release information.