[PATCH 17/20] target/arm: Skip AF and DB updates for AccessType_AT

[Richard Henderson <richard.henderson@linaro.org>]

We are required to skip DB update for AT instructions, and
we are allowed to skip AF updates.  Choose to skip both.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/ptw.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/target/arm/ptw.c b/target/arm/ptw.c
index 19a53ec707..ecb20f65e5 100644
--- a/target/arm/ptw.c
+++ b/target/arm/ptw.c
@@ -58,6 +58,10 @@ typedef struct S1Translate {
      * and will not change the state of the softmmu TLBs.
      */
     bool in_debug;
+    /*
+     * in_at: is this AccessType_AT?
+     */
+    bool in_at;
     /*
      * If this is stage 2 of a stage 1+2 page table walk, then this must
      * be true if stage 1 is an EL0 access; otherwise this is ignored.
@@ -1922,7 +1926,14 @@ static bool get_phys_addr_lpae(CPUARMState *env, S1Translate *ptw,
     descaddr &= ~(hwaddr)(page_size - 1);
     descaddr |= (address & (page_size - 1));
 
-    if (likely(!ptw->in_debug)) {
+    /*
+     * For debug, never change cpu state, so do not update AF or DB.
+     *
+     * For AccessType_AT, DB is not updated (AArch64.SetDirtyFlag),
+     * and it is IMPLEMENTATION DEFINED whether AF is updated
+     * (AArch64.SetAccessFlag; qemu chooses to not update).
+     */
+    if (likely(!ptw->in_debug && !ptw->in_at)) {
         /*
          * Access flag.
          * If HA is enabled, prepare to update the descriptor below.
@@ -3546,6 +3557,7 @@ bool get_phys_addr_for_at(CPUARMState *env, vaddr address,
     S1Translate ptw = {
         .in_mmu_idx = mmu_idx,
         .in_space = space,
+        .in_at = true,
     };
     /*
      * I_MXTJT: Granule protection checks are not performed on the final
-- 
2.43.0