Re: [Qemu-devel] [PATCH for-4.2 01/24] cputlb: Add tlb_set_asid_for_mmuidx

["Alex Bennée" <alex.bennee@linaro.org>]

Richard Henderson <richard.henderson@linaro.org> writes:

> Although we can't do much with ASIDs except remember them, this
> will allow cleanups within target/ that should make things clearer.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>
> ---
> v2: Assert cpu_is_self; only flush idx w/ asid mismatch.
> ---
>  include/exec/cpu-all.h  | 11 +++++++++++
>  include/exec/cpu-defs.h |  2 ++
>  include/exec/exec-all.h | 19 +++++++++++++++++++
>  accel/tcg/cputlb.c      | 26 ++++++++++++++++++++++++++
>  4 files changed, 58 insertions(+)
>
> diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
> index 536ea58f81..40b140cbba 100644
> --- a/include/exec/cpu-all.h
> +++ b/include/exec/cpu-all.h
> @@ -439,4 +439,15 @@ static inline CPUTLB *env_tlb(CPUArchState *env)
>      return &env_neg(env)->tlb;
>  }
>
> +/**
> + * cpu_tlb(env)
> + * @cpu: The generic CPUState
> + *
> + * Return the CPUTLB state associated with the cpu.
> + */
> +static inline CPUTLB *cpu_tlb(CPUState *cpu)
> +{
> +    return &cpu_neg(cpu)->tlb;
> +}
> +
>  #endif /* CPU_ALL_H */
> diff --git a/include/exec/cpu-defs.h b/include/exec/cpu-defs.h
> index 9bc713a70b..73584841c0 100644
> --- a/include/exec/cpu-defs.h
> +++ b/include/exec/cpu-defs.h
> @@ -169,6 +169,8 @@ typedef struct CPUTLBDesc {
>      size_t n_used_entries;
>      /* The next index to use in the tlb victim table.  */
>      size_t vindex;
> +    /* The current ASID for this tlb.  */
> +    uint32_t asid;

is it worth adding a "if used" to the comment. I assume there are arches
that will never set and therefore care about ASID.

Otherwise:

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

>      /* The tlb victim table, in two parts.  */
>      CPUTLBEntry vtable[CPU_VTLB_SIZE];
>      CPUIOTLBEntry viotlb[CPU_VTLB_SIZE];
> diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
> index 16034ee651..9c77aa5bf9 100644
> --- a/include/exec/exec-all.h
> +++ b/include/exec/exec-all.h
> @@ -225,6 +225,21 @@ void tlb_flush_by_mmuidx_all_cpus(CPUState *cpu, uint16_t idxmap);
>   * depend on when the guests translation ends the TB.
>   */
>  void tlb_flush_by_mmuidx_all_cpus_synced(CPUState *cpu, uint16_t idxmap);
> +/**
> + * tlb_set_asid_for_mmuidx:
> + * @cpu: Originating cpu
> + * @asid: Address Space Identifier
> + * @idxmap: bitmap of MMU indexes to set to @asid
> + * @depmap: bitmap of dependent MMU indexes
> + *
> + * Set an ASID for all of @idxmap.  If any previous ASID was different,
> + * then we will flush the mmu idx.  If a flush is required, then also flush
> + * all dependent mmu indicies in @depmap.  This latter is typically used
> + * for secondary page resolution, for implementing virtualization within
> + * the guest.
> + */
> +void tlb_set_asid_for_mmuidx(CPUState *cpu, uint32_t asid,
> +                             uint16_t idxmap, uint16_t dep_idxmap);
>  /**
>   * tlb_set_page_with_attrs:
>   * @cpu: CPU to add this TLB entry for
> @@ -310,6 +325,10 @@ static inline void tlb_flush_by_mmuidx_all_cpus_synced(CPUState *cpu,
>                                                         uint16_t idxmap)
>  {
>  }
> +static inline void tlb_set_asid_for_mmuidx(CPUState *cpu, uint32_t asid,
> +                                           uint16_t idxmap, uint16_t depmap)
> +{
> +}
>  #endif
>
>  #define CODE_GEN_ALIGN           16 /* must be >= of the size of a icache line */
> diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
> index bb9897b25a..c68f57755b 100644
> --- a/accel/tcg/cputlb.c
> +++ b/accel/tcg/cputlb.c
> @@ -540,6 +540,32 @@ void tlb_flush_page_all_cpus_synced(CPUState *src, target_ulong addr)
>      tlb_flush_page_by_mmuidx_all_cpus_synced(src, addr, ALL_MMUIDX_BITS);
>  }
>
> +void tlb_set_asid_for_mmuidx(CPUState *cpu, uint32_t asid, uint16_t idxmap,
> +                             uint16_t depmap)
> +{
> +    CPUTLB *tlb = cpu_tlb(cpu);
> +    uint16_t work, to_flush = 0;
> +
> +    /* It doesn't make sense to set context across cpus.  */
> +    assert_cpu_is_self(cpu);
> +
> +    /*
> +     * We don't support ASIDs except for trivially.
> +     * If there is any change, then we must flush the TLB.
> +     */
> +    for (work = idxmap; work != 0; work &= work - 1) {
> +        int mmu_idx = ctz32(work);
> +        if (tlb->d[mmu_idx].asid != asid) {
> +            tlb->d[mmu_idx].asid = asid;
> +            to_flush |= 1 << mmu_idx;
> +        }
> +    }
> +    if (to_flush) {
> +        to_flush |= depmap;
> +        tlb_flush_by_mmuidx_async_work(cpu, RUN_ON_CPU_HOST_INT(to_flush));
> +    }
> +}
> +
>  /* update the TLBs so that writes to code in the virtual page 'addr'
>     can be detected */
>  void tlb_protect_code(ram_addr_t ram_addr)


--
Alex Bennée