diff options
| author | Richard Henderson <richard.henderson@linaro.org> | 2018-10-18 18:56:16 -0700 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2018-10-19 17:38:48 +0100 |
| commit | 88c9add25e7120e8622796c81ad3f3fb7f8d40e7 (patch) | |
| tree | 33b613d88a75d5ec431b0a2b663eb9b4f4a15ac8 | |
| parent | 5b67106992e2a829119a7902925d6b79cab4ad14 (diff) | |
target/arm: Only flush tlb if ASID changespull-target-arm-20181019
Since QEMU does not implement ASIDs, changes to the ASID must flush the
tlb. However, if the ASID does not change there is no reason to flush.
In testing a boot of the Ubuntu installer to the first menu, this reduces
the number of flushes by 30%, or nearly 600k instances.
Reviewed-by: Aaron Lindsay <aaron@os.amperecomputing.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20181019015617.22583-3-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
| -rw-r--r-- | target/arm/helper.c | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/target/arm/helper.c b/target/arm/helper.c index 20114bf574..bea4d5350d 100644 --- a/target/arm/helper.c +++ b/target/arm/helper.c @@ -2758,12 +2758,10 @@ static void vmsa_tcr_el1_write(CPUARMState *env, const ARMCPRegInfo *ri, static void vmsa_ttbr_write(CPUARMState *env, const ARMCPRegInfo *ri, uint64_t value) { - /* 64 bit accesses to the TTBRs can change the ASID and so we - * must flush the TLB. - */ - if (cpreg_field_is_64bit(ri)) { + /* If the ASID changes (with a 64-bit write), we must flush the TLB. */ + if (cpreg_field_is_64bit(ri) && + extract64(raw_read(env, ri) ^ value, 48, 16) != 0) { ARMCPU *cpu = arm_env_get_cpu(env); - tlb_flush(CPU(cpu)); } raw_write(env, ri, value); |