[PATCH 4/4] target/arm: Enable FEAT_S2FWB for -cpu max

[Peter Maydell]

Enable the FEAT_S2FWB for -cpu max. Since FEAT_S2FWB requires that
CLIDR_EL1.{LoUU,LoUIS} are zero, we explicitly squash these (the
inherited CLIDR_EL1 value from the Cortex-A57 has them as 1).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 docs/system/arm/emulation.rst |  1 +
 target/arm/cpu64.c            | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/docs/system/arm/emulation.rst b/docs/system/arm/emulation.rst
index c3bd0676a87..122306a99f1 100644
--- a/docs/system/arm/emulation.rst
+++ b/docs/system/arm/emulation.rst
@@ -42,6 +42,7 @@ the following architecture extensions:
 - FEAT_PMUv3p4 (PMU Extensions v3.4)
 - FEAT_RDM (Advanced SIMD rounding double multiply accumulate instructions)
 - FEAT_RNG (Random number generator)
+- FEAT_S2FWB (Stage 2 forced Write-Back)
 - FEAT_SB (Speculation Barrier)
 - FEAT_SEL2 (Secure EL2)
 - FEAT_SHA1 (SHA1 instructions)
diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index 2974cbc0d35..ed2831f1f38 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -769,6 +769,15 @@ static void aarch64_max_initfn(Object *obj)
     t = FIELD_DP64(t, MIDR_EL1, REVISION, 0);
     cpu->midr = t;
 
+    /*
+     * We're going to set FEAT_S2FWB, which mandates that 
CLIDR_EL1.{LoUU,LoUIS}
+     * are zero.
+     */
+    u = cpu->clidr;
+    u = FIELD_DP32(u, CLIDR_EL1, LOUIS, 0);
+    u = FIELD_DP32(u, CLIDR_EL1, LOUU, 0);
+    cpu->clidr = u;
+
     t = cpu->isar.id_aa64isar0;
     t = FIELD_DP64(t, ID_AA64ISAR0, AES, 2); /* AES + PMULL */
     t = FIELD_DP64(t, ID_AA64ISAR0, SHA1, 1);
@@ -841,6 +850,7 @@ static void aarch64_max_initfn(Object *obj)
     t = FIELD_DP64(t, ID_AA64MMFR2, VARANGE, 1); /* FEAT_LVA */
     t = FIELD_DP64(t, ID_AA64MMFR2, TTL, 1); /* FEAT_TTL */
     t = FIELD_DP64(t, ID_AA64MMFR2, BBM, 2); /* FEAT_BBM at level 2 */
+    t = FIELD_DP64(t, ID_AA64MMFR2, FWB, 1); /* FEAT_S2FWB */
     cpu->isar.id_aa64mmfr2 = t;
 
     t = cpu->isar.id_aa64zfr0;
-- 
2.25.1