target/arm: Do memory type alignment check when translation disabled

If translation is disabled, the default memory type is Device, which
requires alignment checking.  This is more optimally done early via
the MemOp given to the TCG memory operation.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reported-by: Idan Horowitz <idan.horowitz@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240301204110.656742-6-richard.henderson@linaro.org
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1204
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 32 insertions, 2 deletions

diff --git a/target/arm/tcg/hflags.c b/target/arm/tcg/hflags.c
index 8e5d35d..5da1b0f 100644
--- a/target/arm/tcg/hflags.c
+++ b/target/arm/tcg/hflags.c
@@ -26,6 +26,35 @@ static inline bool fgt_svc(CPUARMState *env, int el)
         FIELD_EX64(env->cp15.fgt_exec[FGTREG_HFGITR], HFGITR_EL2, SVC_EL1);
 }
 
+/* Return true if memory alignment should be enforced. */
+static bool aprofile_require_alignment(CPUARMState *env, int el, uint64_t sctlr)
+{
+#ifdef CONFIG_USER_ONLY
+    return false;
+#else
+    /* Check the alignment enable bit. */
+    if (sctlr & SCTLR_A) {
+        return true;
+    }
+
+    /*
+     * If translation is disabled, then the default memory type is
+     * Device(-nGnRnE) instead of Normal, which requires that alignment
+     * be enforced.  Since this affects all ram, it is most efficient
+     * to handle this during translation.
+     */
+    if (sctlr & SCTLR_M) {
+        /* Translation enabled: memory type in PTE via MAIR_ELx. */
+        return false;
+    }
+    if (el < 2 && (arm_hcr_el2_eff(env) & (HCR_DC | HCR_VM))) {
+        /* Stage 2 translation enabled: memory type in PTE. */
+        return false;
+    }
+    return true;
+#endif
+}
+
 static CPUARMTBFlags rebuild_hflags_common(CPUARMState *env, int fp_el,
                                            ARMMMUIdx mmu_idx,
                                            CPUARMTBFlags flags)
@@ -121,8 +150,9 @@ static CPUARMTBFlags rebuild_hflags_a32(CPUARMState *env, int fp_el,
 {
     CPUARMTBFlags flags = {};
     int el = arm_current_el(env);
+    uint64_t sctlr = arm_sctlr(env, el);
 
-    if (arm_sctlr(env, el) & SCTLR_A) {
+    if (aprofile_require_alignment(env, el, sctlr)) {
         DP_TBFLAG_ANY(flags, ALIGN_MEM, 1);
     }
 
@@ -223,7 +253,7 @@ static CPUARMTBFlags rebuild_hflags_a64(CPUARMState *env, int el, int fp_el,
 
     sctlr = regime_sctlr(env, stage1);
 
-    if (sctlr & SCTLR_A) {
+    if (aprofile_require_alignment(env, el, sctlr)) {
         DP_TBFLAG_ANY(flags, ALIGN_MEM, 1);
     }