[v9,17/20] cpu: TLB_FLAGS_MASK bit to force memory slow path
diff mbox series

Message ID 4b71fd52ebd39e3122f8b702b53ecb04f6af4c26.1566466906.git.tony.nguyen@bt.com
State New
Headers show
Series
  • Invert Endian bit in SPARCv9 MMU TTE
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Commit Message

Tony Nguyen Aug. 23, 2019, 6:36 p.m. UTC
The fast path is taken when TLB_FLAGS_MASK is all zero.

TLB_FORCE_SLOW is simply a TLB_FLAGS_MASK bit to force the slow path,
there are no other side effects.

Signed-off-by: Tony Nguyen <tony.nguyen@bt.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
 include/exec/cpu-all.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Comments

Richard Henderson Aug. 23, 2019, 10:27 p.m. UTC | #1
On 8/23/19 11:36 AM, Tony Nguyen wrote:
> The fast path is taken when TLB_FLAGS_MASK is all zero.
> 
> TLB_FORCE_SLOW is simply a TLB_FLAGS_MASK bit to force the slow path,
> there are no other side effects.
> 
> Signed-off-by: Tony Nguyen <tony.nguyen@bt.com>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  include/exec/cpu-all.h | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)

FYI, while looking at this again, we do not need a new bit.  You can simply set
TLB_MMIO for this use case, like we do for ROM.

This seems to be the only change to be made for this patch set; I can fix this
up myself while queuing.


r~

Patch
diff mbox series

diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
index 536ea58f81..e496f9900f 100644
--- a/include/exec/cpu-all.h
+++ b/include/exec/cpu-all.h
@@ -331,12 +331,18 @@  CPUArchState *cpu_copy(CPUArchState *env);
 #define TLB_MMIO            (1 << (TARGET_PAGE_BITS - 3))
 /* Set if TLB entry must have MMU lookup repeated for every access */
 #define TLB_RECHECK         (1 << (TARGET_PAGE_BITS - 4))
+/* Set if TLB entry must take the slow path.  */
+#define TLB_FORCE_SLOW      (1 << (TARGET_PAGE_BITS - 5))
 
 /* Use this mask to check interception with an alignment mask
  * in a TCG backend.
  */
-#define TLB_FLAGS_MASK  (TLB_INVALID_MASK | TLB_NOTDIRTY | TLB_MMIO \
-                         | TLB_RECHECK)
+#define TLB_FLAGS_MASK \
+    (TLB_INVALID_MASK  \
+     | TLB_NOTDIRTY    \
+     | TLB_MMIO        \
+     | TLB_RECHECK     \
+     | TLB_FORCE_SLOW)
 
 /**
  * tlb_hit_page: return true if page aligned @addr is a hit against the