[PULL,16/20] accel/tcg: Add TLB_CHECK_ALIGNED

Commit Message

Peter Maydell March 5, 2024, 1:52 p.m. UTC

From: Richard Henderson <[e-mail]>

This creates a per-page method for checking of alignment.

Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>
Signed-off-by: Richard Henderson <[e-mail]>
Message-id: [e-mail]
Signed-off-by: Peter Maydell <[e-mail]>
---
 include/exec/cpu-all.h |  4 +++-
 accel/tcg/cputlb.c     | 30 +++++++++++++++++++++++++++---
 2 files changed, 30 insertions(+), 4 deletions(-)

Patch

diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
index bc05dce7abe..1a6510fd3bf 100644
--- a/include/exec/cpu-all.h
+++ b/include/exec/cpu-all.h
@@ -357,8 +357,10 @@  static inline int cpu_mmu_index(CPUState *cs, bool ifetch)
 #define TLB_BSWAP            (1 << 0)
 /* Set if TLB entry contains a watchpoint.  */
 #define TLB_WATCHPOINT       (1 << 1)
+/* Set if TLB entry requires aligned accesses.  */
+#define TLB_CHECK_ALIGNED    (1 << 2)
 
-#define TLB_SLOW_FLAGS_MASK  (TLB_BSWAP | TLB_WATCHPOINT)
+#define TLB_SLOW_FLAGS_MASK  (TLB_BSWAP | TLB_WATCHPOINT | TLB_CHECK_ALIGNED)
 
 /* The two sets of flags must not overlap. */
 QEMU_BUILD_BUG_ON(TLB_FLAGS_MASK & TLB_SLOW_FLAGS_MASK);
diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index ac986cb8ea5..93b1ca810bf 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -1453,9 +1453,8 @@  static int probe_access_internal(CPUState *cpu, vaddr addr,
     flags |= full->slow_flags[access_type];
 
     /* Fold all "mmio-like" bits into TLB_MMIO.  This is not RAM.  */
-    if (unlikely(flags & ~(TLB_WATCHPOINT | TLB_NOTDIRTY))
-        ||
-        (access_type != MMU_INST_FETCH && force_mmio)) {
+    if (unlikely(flags & ~(TLB_WATCHPOINT | TLB_NOTDIRTY | TLB_CHECK_ALIGNED))
+        || (access_type != MMU_INST_FETCH && force_mmio)) {
         *phost = NULL;
         return TLB_MMIO;
     }
@@ -1836,6 +1835,31 @@  static bool mmu_lookup(CPUState *cpu, vaddr addr, MemOpIdx oi,
         tcg_debug_assert((flags & TLB_BSWAP) == 0);
     }
 
+    /*
+     * This alignment check differs from the one above, in that this is
+     * based on the atomicity of the operation. The intended use case is
+     * the ARM memory type field of each PTE, where access to pages with
+     * Device memory type require alignment.
+     */
+    if (unlikely(flags & TLB_CHECK_ALIGNED)) {
+        MemOp size = l->memop & MO_SIZE;
+
+        switch (l->memop & MO_ATOM_MASK) {
+        case MO_ATOM_NONE:
+            size = MO_8;
+            break;
+        case MO_ATOM_IFALIGN_PAIR:
+        case MO_ATOM_WITHIN16_PAIR:
+            size = size ? size - 1 : 0;
+            break;
+        default:
+            break;
+        }
+        if (addr & ((1 << size) - 1)) {
+            cpu_unaligned_access(cpu, addr, type, l->mmu_idx, ra);
+        }
+    }
+
     return crosspage;
 }