Re: [PATCH v2] lib: sbi: Allow platforms to override local TLB operations

On Wed, Jun 17, 2026 at 5:00 PM Xiang W <[email protected]> wrote:
>
> Some T-Head based processors, for example the Sophgo SG2044, have a
> JTLB errata that requires special handling of certain TLB maintenance
> instructions (sfence.vma).
>
> Introduce a sbi_tlb_local_operations structure so platforms can provide
> custom local TLB flush implementations. Use it to implement the JTLB
> workaround on affected SoCs (currently Sophgo SG2044).
>
> Signed-off-by: Xiang W <[email protected]>
> Signed-off-by: Han Gao <[email protected]>

LGTM.

Reviewed-by: Anup Patel <[email protected]>

Applied this patch to the riscv/opensbi repo.

As as separate patch, we should remove the get_tlbr_flush_limit()
from sbi_platform_operations and instead use this new mechanism
to overwrite the local TLB flush behaviour for SiFive FU540 adn FU740.

Thanks,
Anup

> ---
>  include/sbi/sbi_tlb.h                        | 31 +++++++++++++
>  lib/sbi/sbi_tlb.c                            | 46 +++++++++++++++++---
>  platform/generic/include/thead/c9xx_errata.h |  1 +
>  platform/generic/thead/thead-generic.c       | 31 ++++++++++++-
>  4 files changed, 101 insertions(+), 8 deletions(-)
>
> diff --git a/include/sbi/sbi_tlb.h b/include/sbi/sbi_tlb.h
> index 3936e857..0d2198ab 100644
> --- a/include/sbi/sbi_tlb.h
> +++ b/include/sbi/sbi_tlb.h
> @@ -54,6 +54,37 @@ do { \
>
>  #define SBI_TLB_INFO_SIZE              sizeof(struct sbi_tlb_info)
>
> +/** Collection of Local TLB operations */
> +struct sbi_tlb_local_operations {
> +       /** Local fence.i */
> +       void (*local_fence_i)(struct sbi_tlb_info *tinfo);
> +
> +       /** Local supervisor-mode TLB flush */
> +       void (*local_sfence_vma)(struct sbi_tlb_info *tinfo);
> +
> +       /** Local supervisor-mode TLB flush with ASID */
> +       void (*local_sfence_vma_asid)(struct sbi_tlb_info *tinfo);
> +
> +       /** Local G-stage TLB flush for a specific VMID */
> +       void (*local_hfence_gvma_vmid)(struct sbi_tlb_info *tinfo);
> +
> +       /** Local G-stage TLB flush */
> +       void (*local_hfence_gvma)(struct sbi_tlb_info *tinfo);
> +
> +       /** Local VS-stage TLB flush with ASID */
> +       void (*local_hfence_vvma_asid)(struct sbi_tlb_info *tinfo);
> +
> +       /** Local VS-stage TLB flush */
> +       void (*local_hfence_vvma)(struct sbi_tlb_info *tinfo);
> +};
> +
> +/** Get the local TLB operations */
> +const struct sbi_tlb_local_operations *sbi_tlb_get_local_operations(void);
> +
> +/** Set the local TLB operations */
> +void sbi_tlb_set_local_operations(
> +               const struct sbi_tlb_local_operations *ops);
> +
>  void __sbi_sfence_vma_all();
>
>  int sbi_tlb_request(ulong hmask, ulong hbase, struct sbi_tlb_info *tinfo);
> diff --git a/lib/sbi/sbi_tlb.c b/lib/sbi/sbi_tlb.c
> index ada60c32..ab1e3a99 100644
> --- a/lib/sbi/sbi_tlb.c
> +++ b/lib/sbi/sbi_tlb.c
> @@ -29,6 +29,38 @@ static unsigned long tlb_fifo_off;
>  static unsigned long tlb_fifo_mem_off;
>  static unsigned long tlb_range_flush_limit;
>
> +static void sbi_tlb_local_fence_i(struct sbi_tlb_info *tinfo);
> +static void sbi_tlb_local_sfence_vma(struct sbi_tlb_info *tinfo);
> +static void sbi_tlb_local_sfence_vma_asid(struct sbi_tlb_info *tinfo);
> +static void sbi_tlb_local_hfence_gvma_vmid(struct sbi_tlb_info *tinfo);
> +static void sbi_tlb_local_hfence_gvma(struct sbi_tlb_info *tinfo);
> +static void sbi_tlb_local_hfence_vvma_asid(struct sbi_tlb_info *tinfo);
> +static void sbi_tlb_local_hfence_vvma(struct sbi_tlb_info *tinfo);
> +
> +static struct sbi_tlb_local_operations default_tlb_local_ops = {
> +       .local_fence_i = sbi_tlb_local_fence_i,
> +       .local_sfence_vma = sbi_tlb_local_sfence_vma,
> +       .local_sfence_vma_asid = sbi_tlb_local_sfence_vma_asid,
> +       .local_hfence_gvma_vmid = sbi_tlb_local_hfence_gvma_vmid,
> +       .local_hfence_gvma = sbi_tlb_local_hfence_gvma,
> +       .local_hfence_vvma_asid = sbi_tlb_local_hfence_vvma_asid,
> +       .local_hfence_vvma = sbi_tlb_local_hfence_vvma
> +};
> +
> +static const struct sbi_tlb_local_operations *tlb_local_ops =
> +       &default_tlb_local_ops;
> +
> +const struct sbi_tlb_local_operations *sbi_tlb_get_local_operations(void)
> +{
> +       return tlb_local_ops;
> +}
> +
> +void sbi_tlb_set_local_operations(
> +               const struct sbi_tlb_local_operations *ops)
> +{
> +       tlb_local_ops = ops;
> +}
> +
>  void __sbi_sfence_vma_all(void)
>  {
>         __asm__ __volatile("sfence.vma");
> @@ -183,25 +215,25 @@ static void tlb_entry_local_process(struct sbi_tlb_info *data)
>
>         switch (data->type) {
>         case SBI_TLB_FENCE_I:
> -               sbi_tlb_local_fence_i(data);
> +               tlb_local_ops->local_fence_i(data);
>                 break;
>         case SBI_TLB_SFENCE_VMA:
> -               sbi_tlb_local_sfence_vma(data);
> +               tlb_local_ops->local_sfence_vma(data);
>                 break;
>         case SBI_TLB_SFENCE_VMA_ASID:
> -               sbi_tlb_local_sfence_vma_asid(data);
> +               tlb_local_ops->local_sfence_vma_asid(data);
>                 break;
>         case SBI_TLB_HFENCE_GVMA_VMID:
> -               sbi_tlb_local_hfence_gvma_vmid(data);
> +               tlb_local_ops->local_hfence_gvma_vmid(data);
>                 break;
>         case SBI_TLB_HFENCE_GVMA:
> -               sbi_tlb_local_hfence_gvma(data);
> +               tlb_local_ops->local_hfence_gvma(data);
>                 break;
>         case SBI_TLB_HFENCE_VVMA_ASID:
> -               sbi_tlb_local_hfence_vvma_asid(data);
> +               tlb_local_ops->local_hfence_vvma_asid(data);
>                 break;
>         case SBI_TLB_HFENCE_VVMA:
> -               sbi_tlb_local_hfence_vvma(data);
> +               tlb_local_ops->local_hfence_vvma(data);
>                 break;
>         default:
>                 break;
> diff --git a/platform/generic/include/thead/c9xx_errata.h b/platform/generic/include/thead/c9xx_errata.h
> index 40c1587b..7a419e41 100644
> --- a/platform/generic/include/thead/c9xx_errata.h
> +++ b/platform/generic/include/thead/c9xx_errata.h
> @@ -8,6 +8,7 @@
>   */
>  #define THEAD_QUIRK_ERRATA_TLB_FLUSH           BIT(0)
>  #define THEAD_QUIRK_ERRATA_THEAD_PMU           BIT(1)
> +#define THEAD_QUIRK_ERRATA_JTLB                        BIT(2)
>
>  void thead_register_tlb_flush_trap_handler(void);
>
> diff --git a/platform/generic/thead/thead-generic.c b/platform/generic/thead/thead-generic.c
> index ddb4f0bf..8ec90746 100644
> --- a/platform/generic/thead/thead-generic.c
> +++ b/platform/generic/thead/thead-generic.c
> @@ -11,8 +11,10 @@
>  #include <thead/c9xx_pmu.h>
>  #include <sbi/sbi_const.h>
>  #include <sbi/sbi_platform.h>
> +#include <sbi/sbi_pmu.h>
>  #include <sbi/sbi_scratch.h>
>  #include <sbi/sbi_string.h>
> +#include <sbi/sbi_tlb.h>
>  #include <sbi_utils/fdt/fdt_helper.h>
>
>  struct thead_generic_quirks {
> @@ -39,15 +41,38 @@ static int thead_pmu_extensions_init(struct sbi_hart_features *hfeatures)
>         return 0;
>  }
>
> +static void thead_jtlb_local_sfence_vma(struct sbi_tlb_info *tinfo)
> +{
> +       sbi_pmu_ctr_incr_fw(SBI_PMU_FW_SFENCE_VMA_RCVD);
> +       __asm__ __volatile__("sfence.vma");
> +}
> +
> +static void thead_jtlb_local_sfence_vma_asid(struct sbi_tlb_info *tinfo)
> +{
> +       sbi_pmu_ctr_incr_fw(SBI_PMU_FW_SFENCE_VMA_ASID_RCVD);
> +       /* Flush entire MM context for a given ASID */
> +       __asm__ __volatile__("sfence.vma x0, %0"
> +                            :
> +                            : "r"(tinfo->asid)
> +                            : "memory");
> +}
> +
>  static int thead_generic_platform_init(const void *fdt, int nodeoff,
>                                        const struct fdt_match *match)
>  {
>         const struct thead_generic_quirks *quirks = match->data;
> +       static struct sbi_tlb_local_operations tlb_local_ops;
>
>         if (quirks->errata & THEAD_QUIRK_ERRATA_TLB_FLUSH)
>                 generic_platform_ops.early_init = thead_tlb_flush_early_init;
>         if (quirks->errata & THEAD_QUIRK_ERRATA_THEAD_PMU)
>                 generic_platform_ops.extensions_init = thead_pmu_extensions_init;
> +       if (quirks->errata &THEAD_QUIRK_ERRATA_JTLB) {
> +               sbi_memcpy(&tlb_local_ops, sbi_tlb_get_local_operations(), sizeof(tlb_local_ops));
> +               tlb_local_ops.local_sfence_vma = thead_jtlb_local_sfence_vma;
> +               tlb_local_ops.local_sfence_vma_asid = thead_jtlb_local_sfence_vma_asid;
> +               sbi_tlb_set_local_operations(&tlb_local_ops);
> +       }
>
>         return 0;
>  }
> @@ -60,13 +85,17 @@ static const struct thead_generic_quirks thead_pmu_quirks = {
>         .errata = THEAD_QUIRK_ERRATA_THEAD_PMU,
>  };
>
> +static const struct thead_generic_quirks thead_pmu_jtlb_quirks = {
> +       .errata = THEAD_QUIRK_ERRATA_THEAD_PMU | THEAD_QUIRK_ERRATA_JTLB,
> +};
> +
>  static const struct fdt_match thead_generic_match[] = {
>         { .compatible = "canaan,kendryte-k230", .data = &thead_pmu_quirks },
>         { .compatible = "sophgo,cv1800b", .data = &thead_pmu_quirks },
>         { .compatible = "sophgo,cv1812h", .data = &thead_pmu_quirks },
>         { .compatible = "sophgo,sg2000", .data = &thead_pmu_quirks },
>         { .compatible = "sophgo,sg2002", .data = &thead_pmu_quirks },
> -       { .compatible = "sophgo,sg2044", .data = &thead_pmu_quirks },
> +       { .compatible = "sophgo,sg2044", .data = &thead_pmu_jtlb_quirks },
>         { .compatible = "thead,th1520", .data = &thead_th1520_quirks },
>         { },
>  };
> --
> 2.47.3
>

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