[PATCH 5/6] target/arm: Advertise FEAT_ETS for '-cpu max'

[Peter Maydell]

The architectural feature FEAT_ETS (Enhanced Translation
Synchronization) is a set of tightened guarantees about memory
ordering involving translation table walks:

 * if memory access RW1 is ordered-before memory access RW2 then it
   is also ordered-before any translation table walk generated by RW2
   that generates a translation fault, address size fault or access
   fault

 * TLB maintenance on non-exec-permission translations is guaranteed
   complete after a DSB (ie it does not need the context
   synchronization event that you have to have if you don’t have
   FEAT_ETS)

For QEMU’s implementation we don’t reorder translation table walk
accesses, and we guarantee to finish the TLB maintenance as soon as
the TLB op is done (the tlb_flush functions will complete at the end
of the TLB, and TLB ops always end the TB because they’re sysreg
writes).

So we’re already compliant and all we need to do is say so in the ID
registers for the 'max' CPU.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 docs/system/arm/emulation.rst | 1 +
 target/arm/cpu64.c            | 1 +
 target/arm/cpu_tcg.c          | 4 ++++
 3 files changed, 6 insertions(+)

diff --git a/docs/system/arm/emulation.rst b/docs/system/arm/emulation.rst
index 8e494c8bea5..811358fd0a0 100644
--- a/docs/system/arm/emulation.rst
+++ b/docs/system/arm/emulation.rst
@@ -24,6 +24,7 @@ the following architecture extensions:
 - FEAT_Debugv8p4 (Debug changes for v8.4)
 - FEAT_DotProd (Advanced SIMD dot product instructions)
 - FEAT_DoubleFault (Double Fault Extension)
+- FEAT_ETS (Enhanced Translation Synchronization)
 - FEAT_FCMA (Floating-point complex number instructions)
 - FEAT_FHM (Floating-point half-precision multiplication instructions)
 - FEAT_FP16 (Half-precision floating-point data processing)
diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index 78e27f778ac..6d65248f29c 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -1043,6 +1043,7 @@ static void aarch64_max_initfn(Object *obj)
     t = FIELD_DP64(t, ID_AA64MMFR1, LO, 1);       /* FEAT_LOR */
     t = FIELD_DP64(t, ID_AA64MMFR1, PAN, 2);      /* FEAT_PAN2 */
     t = FIELD_DP64(t, ID_AA64MMFR1, XNX, 1);      /* FEAT_XNX */
+    t = FIELD_DP64(t, ID_AA64MMFR1, ETS, 1);      /* FEAT_ETS */
     t = FIELD_DP64(t, ID_AA64MMFR1, HCX, 1);      /* FEAT_HCX */
     cpu->isar.id_aa64mmfr1 = t;
 
diff --git a/target/arm/cpu_tcg.c b/target/arm/cpu_tcg.c
index 3099b38e32b..f63f8cdd954 100644
--- a/target/arm/cpu_tcg.c
+++ b/target/arm/cpu_tcg.c
@@ -67,6 +67,10 @@ void aa32_max_features(ARMCPU *cpu)
     t = FIELD_DP32(t, ID_MMFR4, XNX, 1);          /* FEAT_XNX*/
     cpu->isar.id_mmfr4 = t;
 
+    t = cpu->isar.id_mmfr5;
+    t = FIELD_DP32(t, ID_MMFR5, ETS, 1);          /* FEAT_ETS */
+    cpu->isar.id_mmfr5 = t;
+
     t = cpu->isar.id_pfr0;
     t = FIELD_DP32(t, ID_PFR0, CSV2, 2);          /* FEAT_CVS2 */
     t = FIELD_DP32(t, ID_PFR0, DIT, 1);           /* FEAT_DIT */
-- 
2.25.1