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| <section id="hypervisor-maintenance-interrupt-hmi"> |
| <h1>Hypervisor Maintenance Interrupt (HMI)<a class="headerlink" href="#hypervisor-maintenance-interrupt-hmi" title="Link to this heading">¶</a></h1> |
| <p>Hypervisor Maintenance Interrupt usually reports error related to processor |
| recovery/checkstop, NX/NPU checkstop and Timer facility. Hypervisor then |
| takes this opportunity to analyze and recover from some of these errors. |
| Hypervisor takes assistance from OPAL layer to handle and recover from HMI. |
| After handling HMI, OPAL layer sends the summary of error report and status |
| of recovery action using HMI event. See ref:<cite>opal-messages</cite> for HMI |
| event structure under <a class="reference internal" href="opal-messages.html#opal-msg-hmi-evt"><span class="std std-ref">OPAL_MSG_HMI_EVT</span></a> section.</p> |
| <p>HMI is thread specific. The reason for HMI is available in a per thread |
| Hypervisor Maintenance Exception Register (HMER). A Hypervisor Maintenance |
| Exception Enable Register (HMEER) is per core. Bits from the HMER need to |
| be enabled by the corresponding bits in the HMEER in order to cause an HMI.</p> |
| <p>Several interrupt reasons are routed in parallel to each of the thread |
| specific copies. Each thread can only clear bits in its own HMER. OPAL |
| handler from each thread clears the respective bit from HMER register |
| after handling the error.</p> |
| </section> |
| <section id="list-of-errors-that-causes-hmi"> |
| <h1>List of errors that causes HMI<a class="headerlink" href="#list-of-errors-that-causes-hmi" title="Link to this heading">¶</a></h1> |
| <blockquote> |
| <div><ul> |
| <li><p>CPU Errors</p> |
| <ul class="simple"> |
| <li><p>Processor Core checkstop</p></li> |
| <li><p>Processor retry recovery</p></li> |
| <li><p>NX/NPU/CAPP checkstop.</p></li> |
| </ul> |
| </li> |
| <li><p>Timer facility Errors</p> |
| <ul class="simple"> |
| <li><p>ChipTOD Errors</p></li> |
| </ul> |
| <blockquote> |
| <div><ul class="simple"> |
| <li><p>ChipTOD sync check and parity errors</p></li> |
| <li><p>ChipTOD configuration register parity errors</p></li> |
| <li><p>ChiTOD topology failover</p></li> |
| </ul> |
| </div></blockquote> |
| </li> |
| <li><p>Timebase (TB) errors</p> |
| <blockquote> |
| <div><ul class="simple"> |
| <li><p>TB parity/residue error</p></li> |
| <li><p>TFMR parity and firmware control error</p></li> |
| <li><p>DEC/HDEC/PURR/SPURR parity errors</p></li> |
| </ul> |
| </div></blockquote> |
| </li> |
| </ul> |
| </div></blockquote> |
| </section> |
| <section id="hmi-handling"> |
| <h1>HMI handling<a class="headerlink" href="#hmi-handling" title="Link to this heading">¶</a></h1> |
| <p>A core/NX/NPU checkstops are reported as malfunction alert (HMER bit 0). |
| OPAL handler scans through Fault Isolation Register (FIR) for each |
| core/nx/npu to detect the exact reason for checkstop and reports it back |
| to the host alongwith the disposition.</p> |
| <p>A processor recovery is reported through HMER bits 2, 3 and 11. These are |
| just an informational messages and no extra recovery is required.</p> |
| <p>Timer facility errors are reported through HMER bit 4. These are all |
| recoverable errors. The exact reason for the errors are stored in |
| Timer Facility Management Register (TFMR). Some of the Timer facility |
| errors affects TB and some of them affects TOD. TOD is a per chip |
| Time-Of-Day logic that holds the actual time value of the chip and |
| communicates with every TOD in the system to achieve synchronized |
| timer value within a system. TB is per core register (64-bit) derives its |
| value from ChipTOD at startup and then it gets periodically incremented |
| by STEP signal provided by the TOD. In a multi-socket system TODs are |
| always configured as master/backup TOD under primary/secondary |
| topology configuration respectively.</p> |
| <p>TB error generates HMI on all threads of the affected core. TB errors |
| except DEC/HDEC/PURR/SPURR parity errors, causes TB to stop running |
| making it invalid. As part of TB recovery, OPAL hmi handler synchronizes |
| with all threads, clears the TB errors and then re-sync the TB with TOD |
| value putting it back in running state.</p> |
| <p>TOD errors generates HMI on every core/thread of affected chip. The reason |
| for TOD errors are stored in TOD ERROR register (0x40030). As part of the |
| recovery OPAL hmi handler clears the TOD error and then requests new TOD |
| value from another running chipTOD in the system. Sometimes, if a primary |
| chipTOD is in error, it may need a TOD topology switch to recover from |
| error. A TOD topology switch basically makes a backup as new active master.</p> |
| </section> |
| <section id="opal-handle-hmi"> |
| <span id="id1"></span><h1>OPAL_HANDLE_HMI<a class="headerlink" href="#opal-handle-hmi" title="Link to this heading">¶</a></h1> |
| <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="cp">#define OPAL_HANDLE_HMI 98</span> |
| |
| <span class="kt">int64_t</span><span class="w"> </span><span class="nf">opal_handle_hmi</span><span class="p">(</span><span class="kt">void</span><span class="p">);</span> |
| </pre></div> |
| </div> |
| <p>Superseded by <a class="reference internal" href="#opal-handle-hmi2"><span class="std std-ref">OPAL_HANDLE_HMI2</span></a>, meaning that <a class="reference internal" href="#opal-handle-hmi"><span class="std std-ref">OPAL_HANDLE_HMI</span></a> |
| should only be called if <a class="reference internal" href="#opal-handle-hmi2"><span class="std std-ref">OPAL_HANDLE_HMI2</span></a> is not available.</p> |
| <p>Since <a class="reference internal" href="#opal-handle-hmi2"><span class="std std-ref">OPAL_HANDLE_HMI2</span></a> has been available since the start of POWER9 |
| systems being supported, if you only target POWER9 and above, you can |
| assume the presence of <a class="reference internal" href="#opal-handle-hmi2"><span class="std std-ref">OPAL_HANDLE_HMI2</span></a>.</p> |
| </section> |
| <section id="opal-handle-hmi2"> |
| <span id="id2"></span><h1>OPAL_HANDLE_HMI2<a class="headerlink" href="#opal-handle-hmi2" title="Link to this heading">¶</a></h1> |
| <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="cp">#define OPAL_HANDLE_HMI2 166</span> |
| |
| <span class="kt">int64_t</span><span class="w"> </span><span class="nf">opal_handle_hmi2</span><span class="p">(</span><span class="n">__be64</span><span class="w"> </span><span class="o">*</span><span class="n">out_flags</span><span class="p">);</span> |
| </pre></div> |
| </div> |
| <p>When OS host gets an Hypervisor Maintenance Interrupt (HMI), it must call |
| <a class="reference internal" href="#opal-handle-hmi"><span class="std std-ref">OPAL_HANDLE_HMI</span></a> or <a class="reference internal" href="#opal-handle-hmi2"><span class="std std-ref">OPAL_HANDLE_HMI2</span></a>. The <a class="reference internal" href="#opal-handle-hmi"><span class="std std-ref">OPAL_HANDLE_HMI</span></a> |
| is an old interface. <a class="reference internal" href="#opal-handle-hmi2"><span class="std std-ref">OPAL_HANDLE_HMI2</span></a> is newly introduced opal call |
| that returns direct info to the OS. It returns a 64-bit flag mask currently |
| set to provide info about which timer facilities were lost, and whether an |
| event was generated. This information will help OS to take respective |
| actions.</p> |
| <p>In case where opal hmi handler is unable to recover from TOD or TB errors, |
| it would flag <code class="docutils literal notranslate"><span class="pre">OPAL_HMI_FLAGS_TOD_TB_FAIL</span></code> to indicate OS that TB is |
| dead. This information then can be used by OS to make sure that the |
| functions relying on TB value (e.g. udelay()) are aware of TB not ticking. |
| This will avoid OS getting stuck or hang during its way to panic path.</p> |
| <section id="parameters"> |
| <h2>Parameters<a class="headerlink" href="#parameters" title="Link to this heading">¶</a></h2> |
| <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n">__be64</span><span class="w"> </span><span class="o">*</span><span class="n">out_flags</span><span class="p">;</span> |
| </pre></div> |
| </div> |
| <p>Returns the 64-bit flag mask that provides info about which timer facilities |
| were lost, and whether an event was generated.</p> |
| <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="cm">/* OPAL_HANDLE_HMI2 out_flags */</span> |
| <span class="k">enum</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="n">OPAL_HMI_FLAGS_TB_RESYNC</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="mi">1ull</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="mi">0</span><span class="p">),</span><span class="w"> </span><span class="cm">/* Timebase has been resynced */</span> |
| <span class="w"> </span><span class="n">OPAL_HMI_FLAGS_DEC_LOST</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="mi">1ull</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="mi">1</span><span class="p">),</span><span class="w"> </span><span class="cm">/* DEC lost, needs to be reprogrammed */</span> |
| <span class="w"> </span><span class="n">OPAL_HMI_FLAGS_HDEC_LOST</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="mi">1ull</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="mi">2</span><span class="p">),</span><span class="w"> </span><span class="cm">/* HDEC lost, needs to be reprogrammed */</span> |
| <span class="w"> </span><span class="n">OPAL_HMI_FLAGS_TOD_TB_FAIL</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="mi">1ull</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="mi">3</span><span class="p">),</span><span class="w"> </span><span class="cm">/* TOD/TB recovery failed. */</span> |
| <span class="w"> </span><span class="n">OPAL_HMI_FLAGS_NEW_EVENT</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="mi">1ull</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="mi">63</span><span class="p">),</span><span class="w"> </span><span class="cm">/* An event has been created */</span> |
| <span class="p">};</span> |
| </pre></div> |
| </div> |
| <dl class="simple" id="opal-hmi-flags-tod-tb-fail"> |
| <dt>OPAL_HMI_FLAGS_TOD_TB_FAIL</dt><dd><p>The Time of Day (TOD) / Timebase facility has failed. This is probably fatal |
| for the OS, and requires the OS to be very careful to not call any function |
| that may rely on it, usually as it heads down a <cite>panic()</cite> code path. |
| This code path should be <a class="reference internal" href="opal-cec-reboot-6-116.html#opal-cec-reboot2"><span class="std std-ref">OPAL_CEC_REBOOT2</span></a> with the OPAL_REBOOT_PLATFORM_ERROR |
| option. Details of the failure are likely delivered as part of HMI events if |
| <cite>OPAL_HMI_FLAGS_NEW_EVENT</cite> is set.</p> |
| </dd> |
| </dl> |
| </section> |
| </section> |
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| <h3><a href="../index.html">Table of Contents</a></h3> |
| <ul> |
| <li><a class="reference internal" href="#">Hypervisor Maintenance Interrupt (HMI)</a></li> |
| <li><a class="reference internal" href="#list-of-errors-that-causes-hmi">List of errors that causes HMI</a></li> |
| <li><a class="reference internal" href="#hmi-handling">HMI handling</a></li> |
| <li><a class="reference internal" href="#opal-handle-hmi">OPAL_HANDLE_HMI</a></li> |
| <li><a class="reference internal" href="#opal-handle-hmi2">OPAL_HANDLE_HMI2</a><ul> |
| <li><a class="reference internal" href="#parameters">Parameters</a></li> |
| </ul> |
| </li> |
| </ul> |
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