From 3bf08168b2f84dc6e16a107fdf90be59586caf5d Mon Sep 17 00:00:00 2001
From: John Hauser <31252952+jhauser-us@users.noreply.github.com>
Date: Tue, 17 Aug 2021 14:30:36 -0700
Subject: Make explicit the priorities of synch. exceptions of H extension
 (#711)

* Make explicit the priorities of synch. exceptions of H extension

* "page guest-fault" -> "guest-page fault"
---
 src/hypervisor.tex | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/src/hypervisor.tex b/src/hypervisor.tex
index e6262a0..97c8615 100644
--- a/src/hypervisor.tex
+++ b/src/hypervisor.tex
@@ -2750,6 +2750,59 @@ Because TSR and TVM in {\tt mstatus} are intended to impact only S-mode
 (HS-mode), they are ignored for determining exceptions in VS-mode.
 \end{commentary}
 
+\begin{table*}[htbp]
+\begin{center}
+\begin{tabular}{|l|r|l|}
+  \hline
+  Priority      & Exception Code & Description \\
+  \hline
+  {\em Highest} &            3 & Instruction address breakpoint \\
+  \hline
+                &           12 & Instruction page fault \\
+  \hline
+                &           20 & Instruction guest-page fault \\
+  \hline
+                &            1 & Instruction access fault \\
+  \hline
+                &            2 & Illegal instruction \\
+                &           22 & Virtual instruction \\
+                &            0 & Instruction address misaligned \\
+                & 8, 9, 10, 11 & Environment call \\
+                &            3 & Environment break \\
+                &            3 & Load/Store/AMO address breakpoint \\
+  \hline
+  {\em Optionally, these may have}
+                &            6 & Store/AMO address misaligned \\
+  {\em lowest priority instead.}
+                &            4 & Load address misaligned \\
+  \hline
+                &           15 & Store/AMO page fault \\
+                &           13 & Load page fault \\
+  \hline
+                &           23 & Store/AMO guest-page fault \\
+                &           21 & Load guest-page fault \\
+  \hline
+                &            7 & Store/AMO access fault \\
+                &            5 & Load access fault \\
+  \hline
+\end{tabular}
+\end{center}
+\caption{%
+Synchronous exception priority when the hypervisor extension is
+implemented.%
+}
+\label{tab:HSyncExcPrio}
+\end{table*}
+
+If an instruction raises multiple synchronous exceptions, the
+decreasing priority order of Table~\ref{tab:HSyncExcPrio} indicates
+which exception is taken and reported in {\tt mcause} or {\tt scause}.
+A virtual instruction exception has the same priority as an illegal
+instruction exception, and a guest-page fault has lower priority than
+a corresponding page fault.
+
+\FloatBarrier
+
 \subsection{Trap Entry}
 
 When a trap occurs in HS-mode or U-mode, it goes to M-mode, unless
-- 
cgit v1.1