target/arm: Implement FEAT_HAFDBS, dirty bit portion
Perform the atomic update for hardware management of the dirty bit.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20221024051851.3074715-14-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/target/arm/ptw.c b/target/arm/ptw.c
index 9941fa0..a1f4ae6 100644
--- a/target/arm/ptw.c
+++ b/target/arm/ptw.c
@@ -1445,6 +1445,22 @@
goto do_fault;
}
}
+
+ /*
+ * Dirty Bit.
+ * If HD is enabled, pre-emptively set/clear the appropriate AP/S2AP
+ * bit for writeback. The actual write protection test may still be
+ * overridden by tableattrs, to be merged below.
+ */
+ if (param.hd
+ && extract64(descriptor, 51, 1) /* DBM */
+ && access_type == MMU_DATA_STORE) {
+ if (regime_is_stage2(mmu_idx)) {
+ new_descriptor |= 1ull << 7; /* set S2AP[1] */
+ } else {
+ new_descriptor &= ~(1ull << 7); /* clear AP[2] */
+ }
+ }
}
/*
