[PATCH v2 9/9] target/arm: Do memory type alignment check when translation enabled

[Richard Henderson]

If translation is enabled, and the PTE memory type is Device,
enable checking alignment via TLB_CHECK_ALIGNMENT.  While the
check is done later than it should be per the ARM, it's better
than not performing the check at all.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/ptw.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/target/arm/ptw.c b/target/arm/ptw.c
index 37bcb17a9e..8dcd5d80ce 100644
--- a/target/arm/ptw.c
+++ b/target/arm/ptw.c
@@ -227,6 +227,16 @@ static bool regime_translation_disabled(CPUARMState *env, 
ARMMMUIdx mmu_idx,
     return (regime_sctlr(env, mmu_idx) & SCTLR_M) == 0;
 }
 
+static bool S1_attrs_are_device(uint8_t attrs)
+{
+    /*
+     * This slightly under-decodes the MAIR_ELx field:
+     * 0b0000dd01 is Device with FEAT_XS, otherwise UNPREDICTABLE;
+     * 0b0000dd1x is UNPREDICTABLE.
+     */
+    return (attrs & 0xf0) == 0;
+}
+
 static bool S2_attrs_are_device(uint64_t hcr, uint8_t attrs)
 {
     /*
@@ -1274,6 +1284,7 @@ static bool get_phys_addr_lpae(CPUARMState *env, 
S1Translate *ptw,
     bool aarch64 = arm_el_is_aa64(env, el);
     uint64_t descriptor, new_descriptor;
     bool nstable;
+    bool device;
 
     /* TODO: This code does not support shareability levels. */
     if (aarch64) {
@@ -1623,6 +1634,8 @@ static bool get_phys_addr_lpae(CPUARMState *env, 
S1Translate *ptw,
     if (regime_is_stage2(mmu_idx)) {
         result->cacheattrs.is_s2_format = true;
         result->cacheattrs.attrs = extract32(attrs, 2, 4);
+        device = S2_attrs_are_device(arm_hcr_el2_eff_secstate(env, is_secure),
+                                     result->cacheattrs.attrs);
     } else {
         /* Index into MAIR registers for cache attributes */
         uint8_t attrindx = extract32(attrs, 2, 3);
@@ -1635,6 +1648,21 @@ static bool get_phys_addr_lpae(CPUARMState *env, 
S1Translate *ptw,
         if (aarch64 && cpu_isar_feature(aa64_bti, cpu)) {
             result->f.guarded = extract64(attrs, 50, 1); /* GP */
         }
+        device = S1_attrs_are_device(result->cacheattrs.attrs);
+    }
+
+    /*
+     * Enable alignment checks on Device memory.
+     *
+     * Per R_XCHFJ, this check is mis-ordered, in that this alignment check
+     * should have priority 30, while the permission check should be next at
+     * priority 31 and stage2 translation faults come after that.
+     * Due to the way the TCG softmmu TLB operates, we will have implicitly
+     * done the permission check and the stage2 lookup in finding the TLB
+     * entry, so the alignment check cannot be done sooner.
+     */
+    if (device) {
+        result->f.tlb_fill_flags |= TLB_CHECK_ALIGNED;
     }
 
     /*
-- 
2.34.1