Added clarification about the contained trap on Ssstrict.

Closes #173.
riscv · Jul 16, 2024 · 1fe6f65 · 1fe6f65
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diff --git a/src/rva23-profile.adoc b/src/rva23-profile.adoc
@@ -351,6 +351,19 @@ The following are new privileged expansion options in RVA23S64
 NOTE: Ssstrict does not prescribe behavior for the custom encoding
 spaces or CSRs.
 
+NOTE: Ssstrict definition applies to the execution environment
+claiming to be RVA23-compatible, which must have the hypervisor
+extension. That execution environment will take a contained trap to
+supervisor-mode (however that trap is implemented, including, but not
+limited to, emulation/delegation in the outer execution
+environment). Ssstrict (and all the other RVA23 mandates and options)
+do not apply to any guest VMs run by a hypervisor. An RVA23 hypervisor
+can provide guest VMs that are also RVA23-compatible but with an
+expanded set of emulated standard instructions. An RVA23 hypervisor
+can also choose to implement guest VMs that are not RVA23 compatible
+(e.g., lacking H, or only RVA20).
+
+
 - *Svvptc* Transitions from invalid to valid PTEs will be visible in
  bounded time without an explicit memory-management fence.
 

diff --git a/src/rvb23-profile.adoc b/src/rvb23-profile.adoc
@@ -367,6 +367,18 @@ also privileged expansion options in RVA23S64:
 NOTE: Ssstrict does not prescribe behavior for the custom encoding
 spaces or CSRs.
 
+NOTE: Ssstrict definition applies to the execution environment
+claiming to be RVA23-compatible, which must have the hypervisor
+extension. That execution environment will take a contained trap to
+supervisor-mode (however that trap is implemented, including, but not
+limited to, emulation/delegation in the outer execution
+environment). Ssstrict (and all the other RVA23 mandates and options)
+do not apply to any guest VMs run by a hypervisor. An RVA23 hypervisor
+can provide guest VMs that are also RVA23-compatible but with an
+expanded set of emulated standard instructions. An RVA23 hypervisor
+can also choose to implement guest VMs that are not RVA23 compatible
+(e.g., lacking H, or only RVA20).
+
 - *Svvptc* Transitions from invalid to valid PTEs will be visible in
  bounded time without an explicit memory-management fence.