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Re: [Qemu-devel] [PATCH v2 3/3] target/arm: Flush only the TLBs affected
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH v2 3/3] target/arm: Flush only the TLBs affected by TTBR*_EL1 |
Date: |
Fri, 19 Oct 2018 15:28:52 +0100 |
On 19 October 2018 at 02:56, Richard Henderson
<address@hidden> wrote:
> Only the EL0 and EL1 TLBs are affected by the EL1 register,
> so flush only 2 of the 8 TLBs.
>
> In testing a boot of the Ubuntu installer to the first menu, this
> accounts for nearly all of the full tlb flushes: all but 11k of
> the 1.2M instances without the patch.
>
> Signed-off-by: Richard Henderson <address@hidden>
> ---
> target/arm/helper.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index ed70ac645e..3ba8e66487 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -2706,14 +2706,16 @@ static void vmsa_tcr_el1_write(CPUARMState *env,
> const ARMCPRegInfo *ri,
> tcr->raw_tcr = value;
> }
>
> -static void vmsa_ttbr_write(CPUARMState *env, const ARMCPRegInfo *ri,
> - uint64_t value)
> +static void vmsa_ttbr_el1_write(CPUARMState *env, const ARMCPRegInfo *ri,
> + uint64_t value)
> {
> /* 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));
> + tlb_flush_by_mmuidx(CPU(cpu),
> + ARMMMUIdxBit_S12NSE1 |
> + ARMMMUIdxBit_S12NSE0);
This isn't taking account of the possibility of secure mode.
ARMMMUIdxBit_S1SE0 and ARMMMUIdxBit_S1SE1 might also be affected.
And for AArch32, this writefn is used for the secure-banked versions
of TTBR0/TTBR1, which means ARMMMUIdxBit_S1E3 may also need flushing.
thanks
-- PMM