arm: don't do S1 translation in Arch_setMRs_fault

For a VM fault in a hypervisor context, 32-bit Arm translated the IP
address into an IPA, while 64-bit Arm did not. The previous commit
made these consistent by performing the translation on both.

After investigation and discussion, the 32-bit Arm behaviour was
declared a bug: reporting an IPA (instead of a VA) to the VMM is not
very useful and can cause issues when the fault message is not sent
immediately (SELFOUR-1602). This commit, therefore, removes all stage 1
translation from Arch_setMRs_fault on Arm platforms.

Signed-off-by: Rafal Kolanski <[email protected]>

CHANGES

@@ -22,7 +22,7 @@ description indicates whether it is SOURCE-COMPATIBLE, BINARY-COMPATIBLE, or BRE
 Further information about [seL4 releases](https://docs.sel4.systems/sel4_release/) is available.
 
 ---
-Upcoming release: BINARY COMPATIBLE
+Upcoming release: BREAKING
 
 ## Changes
 
@@ -42,6 +42,8 @@ Upcoming release: BINARY COMPATIBLE
 * Removed obsolete define `HAVE_AUTOCONF`
 * Removed user address space reserved slots restriction on 40bit PA platforms when KernelArmHypervisorSupport is set.
   This change is reflected in the definition of the seL4_UserTop constant that holds the largest user virtual address.
+* aarch32 VM fault messages now deliver original (untranslated) faulting IP in a hypervisor context, matching
+  aarch64 behaviour.
 
 ## Upgrade Notes
 ---

include/arch/arm/arch/64/mode/machine.h

@@ -377,10 +377,5 @@ void arch_clean_invalidate_L1_caches(word_t type);
 
 static inline paddr_t addressTranslateS1(vptr_t vaddr)
 {
-#ifdef CONFIG_ARM_HYPERVISOR_SUPPORT
     return ats1e1r(vaddr);
-#else
-    /* shouldn't be called on non-hyp, added for consistency with AArch32 */
-    return vaddr;
-#endif
 }

src/arch/arm/api/faults.c

@@ -34,14 +34,7 @@ word_t Arch_setMRs_fault(tcb_t *sender, tcb_t *receiver, word_t *receiveIPCBuffe
 {
     switch (faultType) {
     case seL4_Fault_VMFault: {
-        if (config_set(CONFIG_ARM_HYPERVISOR_SUPPORT)) {
-            word_t ipa, va;
-            va = getRestartPC(sender);
-            ipa = (addressTranslateS1(va) & ~MASK(PAGE_BITS)) | (va & MASK(PAGE_BITS));
-            setMR(receiver, receiveIPCBuffer, seL4_VMFault_IP, ipa);
-        } else {
-            setMR(receiver, receiveIPCBuffer, seL4_VMFault_IP, getRestartPC(sender));
-        }
+        setMR(receiver, receiveIPCBuffer, seL4_VMFault_IP, getRestartPC(sender));
         setMR(receiver, receiveIPCBuffer, seL4_VMFault_Addr,
               seL4_Fault_VMFault_get_address(sender->tcbFault));
         setMR(receiver, receiveIPCBuffer, seL4_VMFault_PrefetchFault,