cputlb: Byte swap memory transaction attribute

Notice new attribute, byte swap, and force the transaction through the
memory slow path.

Required by architectures that can invert endianness of memory
transaction, e.g. SPARC64 has the Invert Endian TTE bit.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Tony Nguyen <tony.nguyen@bt.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <2a10a1f1c00a894af1212c8f68ef09c2966023c1.1566466906.git.tony.nguyen@bt.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index 3c9e634d99828e2cb69d011bbddb27ad84508d6a..d9787cc8931093c9a03c93c027463abb9d5646a7 100644 (file)
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -738,6 +738,10 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong vaddr,
          */
         address |= TLB_RECHECK;
     }
+    if (attrs.byte_swap) {
+        /* Force the access through the I/O slow path.  */
+        address |= TLB_MMIO;
+    }
     if (!memory_region_is_ram(section->mr) &&
         !memory_region_is_romd(section->mr)) {
         /* IO memory case */
@@ -891,6 +895,10 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
     bool locked = false;
     MemTxResult r;
 
+    if (iotlbentry->attrs.byte_swap) {
+        op ^= MO_BSWAP;
+    }
+
     section = iotlb_to_section(cpu, iotlbentry->addr, iotlbentry->attrs);
     mr = section->mr;
     mr_offset = (iotlbentry->addr & TARGET_PAGE_MASK) + addr;
@@ -933,6 +941,10 @@ static void io_writex(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
     bool locked = false;
     MemTxResult r;
 
+    if (iotlbentry->attrs.byte_swap) {
+        op ^= MO_BSWAP;
+    }
+
     section = iotlb_to_section(cpu, iotlbentry->addr, iotlbentry->attrs);
     mr = section->mr;
     mr_offset = (iotlbentry->addr & TARGET_PAGE_MASK) + addr;

diff --git a/include/exec/memattrs.h b/include/exec/memattrs.h
index d4a3477d71d3e079968a262287e0bc7a1a6c65c5..95f2d20d55b8266903eb430084a2f8b7c39759e7 100644 (file)
--- a/include/exec/memattrs.h
+++ b/include/exec/memattrs.h
@@ -37,6 +37,8 @@ typedef struct MemTxAttrs {
     unsigned int user:1;
     /* Requester ID (for MSI for example) */
     unsigned int requester_id:16;
+    /* Invert endianness for this page */
+    unsigned int byte_swap:1;
     /*
      * The following are target-specific page-table bits.  These are not
      * related to actual memory transactions at all.  However, this structure