Re: [PATCH] platform: Allow platforms to customize TLB operations

On Fri, May 29, 2026 at 1:04 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).
>
> Enable the JTLB workaround for affected boards.
>
> Signed-off-by: Xiang W <[email protected]>
> Signed-off-by: Han Gao <[email protected]>
> ---
>  include/sbi/sbi_platform.h                   | 162 +++++++++++++++++++
>  lib/sbi/sbi_tlb.c                            |  28 ++++
>  platform/generic/include/thead/c9xx_errata.h |   1 +
>  platform/generic/thead/thead-generic.c       |  26 ++-
>  4 files changed, 216 insertions(+), 1 deletion(-)
>
> diff --git a/include/sbi/sbi_platform.h b/include/sbi/sbi_platform.h
> index fe382b56..911b37bf 100644
> --- a/include/sbi/sbi_platform.h
> +++ b/include/sbi/sbi_platform.h
> @@ -56,6 +56,7 @@ struct sbi_domain_memregion;
>  struct sbi_ecall_return;
>  struct sbi_trap_regs;
>  struct sbi_hart_features;
> +struct sbi_tlb_info;
>  union sbi_ldst_data;
>
>  /** Possible feature flags of a platform */
> @@ -125,6 +126,27 @@ struct sbi_platform_operations {
>         /** Get tlb fifo num entries*/
>         u32 (*get_tlb_num_entries)(void);
>
> +       /** Platform hook for custom fence.i */
> +       void (*local_fence_i)(struct sbi_tlb_info *tinfo);
> +
> +       /** Platform hook for custom supervisor-mode TLB flush */
> +       void (*local_sfence_vma)(struct sbi_tlb_info *tinfo);
> +
> +       /** Platform hook for custom supervisor-mode TLB flush with ASID */
> +       void (*local_sfence_vma_asid)(struct sbi_tlb_info *tinfo);
> +
> +       /** Platform hook for custom G-stage TLB flush for a specific VMID */
> +       void (*local_hfence_gvma_vmid)(struct sbi_tlb_info *tinfo);
> +
> +       /** Platform hook for custom G-stage TLB flush */
> +       void (*local_hfence_gvma)(struct sbi_tlb_info *tinfo);
> +
> +       /** Platform hook for custom VS-stage TLB flush with ASID */
> +       void (*local_hfence_vvma_asid)(struct sbi_tlb_info *tinfo);
> +
> +       /** Platform hook for custom VS-stage TLB flush */
> +       void (*local_hfence_vvma)(struct sbi_tlb_info *tinfo);
> +

Better approach will be to not extend struct sbi_platform_operations,
instead have the following interface in sbi_tlb.h:

/** 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 *tlb_local_ops);

The sbi_tlb.c must implement default_tlb_local_ops using
existing sbi_tlb_local_xyz() static functions and this will be
used by default if platform does not override it using
sbi_tlb_set_local_operations().

Regards,
Anup

>         /** Initialize platform timer during cold boot */
>         int (*timer_init)(void);
>
> @@ -313,6 +335,146 @@ static inline u32 sbi_platform_tlb_fifo_num_entries(const struct sbi_platform *p
>         return sbi_hart_count();
>  }
>
> +/**
> + * Platform hook for custom fence.i
> + *
> + * @param plat pointer to struct sbi_platform
> + * @paeam tinfo pointer to struct sbi_tlb_info
> + *
> + * @return 0 indicates that the platform supports the operation and the
> + * operation was successful; otherwise, a normal operation needs to be performed.
> + */
> +static inline u32 sbi_platform_local_fence_i(
> +                                       const struct sbi_platform *plat,
> +                                       struct sbi_tlb_info *tinfo)
> +{
> +       if (plat && sbi_platform_ops(plat)->local_fence_i) {
> +               sbi_platform_ops(plat)->local_fence_i(tinfo);
> +               return 0;
> +       }
> +       return SBI_ENOTSUPP;
> +}
> +
> +/**
> + * Platform hook for custom supervisor-mode TLB flush
> + *
> + * @param plat pointer to struct sbi_platform
> + * @paeam tinfo pointer to struct sbi_tlb_info
> + *
> + * @return 0 indicates that the platform supports the operation and the
> + * operation was successful; otherwise, a normal operation needs to be performed.
> + */
> +static inline u32 sbi_platform_local_sfence_vma(
> +                                       const struct sbi_platform *plat,
> +                                       struct sbi_tlb_info *tinfo)
> +{
> +       if (plat && sbi_platform_ops(plat)->local_sfence_vma) {
> +               sbi_platform_ops(plat)->local_sfence_vma(tinfo);
> +               return 0;
> +       }
> +       return SBI_ENOTSUPP;
> +}
> +
> +/**
> + * Platform hook for custom supervisor-mode TLB flush with ASID
> + *
> + * @param plat pointer to struct sbi_platform
> + * @paeam tinfo pointer to struct sbi_tlb_info
> + *
> + * @return 0 indicates that the platform supports the operation and the
> + * operation was successful; otherwise, a normal operation needs to be performed.
> + */
> +static inline u32 sbi_platform_local_sfence_vma_asid(
> +                                       const struct sbi_platform *plat,
> +                                       struct sbi_tlb_info *tinfo)
> +{
> +       if (plat && sbi_platform_ops(plat)->local_sfence_vma_asid) {
> +               sbi_platform_ops(plat)->local_sfence_vma_asid(tinfo);
> +               return 0;
> +       }
> +       return SBI_ENOTSUPP;
> +}
> +
> +/**
> + * Platform hook for custom G-stage TLB flush for a specific VMID
> + *
> + * @param plat pointer to struct sbi_platform
> + * @paeam tinfo pointer to struct sbi_tlb_info
> + *
> + * @return 0 indicates that the platform supports the operation and the
> + * operation was successful; otherwise, a normal operation needs to be performed.
> + */
> +static inline u32 sbi_platform_local_hfence_gvma_vmid(
> +                                       const struct sbi_platform *plat,
> +                                       struct sbi_tlb_info *tinfo)
> +{
> +       if (plat && sbi_platform_ops(plat)->local_hfence_gvma_vmid) {
> +               sbi_platform_ops(plat)->local_hfence_gvma_vmid(tinfo);
> +               return 0;
> +       }
> +       return SBI_ENOTSUPP;
> +}
> +
> +/**
> + * Platform hook for custom G-stage TLB flush
> + *
> + * @param plat pointer to struct sbi_platform
> + * @paeam tinfo pointer to struct sbi_tlb_info
> + *
> + * @return 0 indicates that the platform supports the operation and the
> + * operation was successful; otherwise, a normal operation needs to be performed.
> + */
> +static inline u32 sbi_platform_local_hfence_gvma(
> +                                       const struct sbi_platform *plat,
> +                                       struct sbi_tlb_info *tinfo)
> +{
> +       if (plat && sbi_platform_ops(plat)->local_hfence_gvma) {
> +               sbi_platform_ops(plat)->local_hfence_gvma(tinfo);
> +               return 0;
> +       }
> +       return SBI_ENOTSUPP;
> +}
> +
> +/**
> + * Platform hook for custom VS-stage TLB flush with ASID
> + *
> + * @param plat pointer to struct sbi_platform
> + * @paeam tinfo pointer to struct sbi_tlb_info
> + *
> + * @return 0 indicates that the platform supports the operation and the
> + * operation was successful; otherwise, a normal operation needs to be performed.
> + */
> +static inline u32 sbi_platform_local_hfence_vvma_asid(
> +                                       const struct sbi_platform *plat,
> +                                       struct sbi_tlb_info *tinfo)
> +{
> +       if (plat && sbi_platform_ops(plat)->local_hfence_vvma_asid) {
> +               sbi_platform_ops(plat)->local_hfence_vvma_asid(tinfo);
> +               return 0;
> +       }
> +       return SBI_ENOTSUPP;
> +}
> +
> +/**
> + * Platform hook for custom VS-stage TLB flush
> + *
> + * @param plat pointer to struct sbi_platform
> + * @paeam tinfo pointer to struct sbi_tlb_info
> + *
> + * @return 0 indicates that the platform supports the operation and the
> + * operation was successful; otherwise, a normal operation needs to be performed.
> + */
> +static inline u32 sbi_platform_local_hfence_vvma(
> +                                       const struct sbi_platform *plat,
> +                                       struct sbi_tlb_info *tinfo)
> +{
> +       if (plat && sbi_platform_ops(plat)->local_hfence_vvma) {
> +               sbi_platform_ops(plat)->local_hfence_vvma(tinfo);
> +               return 0;
> +       }
> +       return SBI_ENOTSUPP;
> +}
> +
>  /**
>   * Get total number of HARTs supported by the platform
>   *
> diff --git a/lib/sbi/sbi_tlb.c b/lib/sbi/sbi_tlb.c
> index ada60c32..69b8fb48 100644
> --- a/lib/sbi/sbi_tlb.c
> +++ b/lib/sbi/sbi_tlb.c
> @@ -46,6 +46,10 @@ static void sbi_tlb_local_hfence_vvma(struct sbi_tlb_info *tinfo)
>         hgatp = csr_swap(CSR_HGATP,
>                          (vmid << HGATP_VMID_SHIFT) & HGATP_VMID_MASK);
>
> +       if (sbi_platform_local_hfence_gvma(
> +                       sbi_platform_thishart_ptr(), tinfo) == SBI_OK)
> +               gito done;
> +
>         if ((start == 0 && size == 0) || (size == SBI_TLB_FLUSH_ALL)) {
>                 __sbi_hfence_vvma_all();
>                 goto done;
> @@ -67,6 +71,10 @@ static void sbi_tlb_local_hfence_gvma(struct sbi_tlb_info *tinfo)
>
>         sbi_pmu_ctr_incr_fw(SBI_PMU_FW_HFENCE_GVMA_RCVD);
>
> +       if (sbi_platform_local_hfence_gvma(
> +                       sbi_platform_thishart_ptr(), tinfo) == SBI_OK)
> +               return;
> +
>         if ((start == 0 && size == 0) || (size == SBI_TLB_FLUSH_ALL)) {
>                 __sbi_hfence_gvma_all();
>                 return;
> @@ -85,6 +93,10 @@ static void sbi_tlb_local_sfence_vma(struct sbi_tlb_info *tinfo)
>
>         sbi_pmu_ctr_incr_fw(SBI_PMU_FW_SFENCE_VMA_RCVD);
>
> +       if (sbi_platform_local_sfence_vma(
> +                       sbi_platform_thishart_ptr(), tinfo) == SBI_OK)
> +               return;
> +
>         if ((start == 0 && size == 0) || (size == SBI_TLB_FLUSH_ALL)) {
>                 __sbi_sfence_vma_all();
>                 return;
> @@ -111,6 +123,10 @@ static void sbi_tlb_local_hfence_vvma_asid(struct sbi_tlb_info *tinfo)
>         hgatp = csr_swap(CSR_HGATP,
>                          (vmid << HGATP_VMID_SHIFT) & HGATP_VMID_MASK);
>
> +       if (sbi_platform_local_hfence_vvma_asid(
> +                       sbi_platform_thishart_ptr(), tinfo) == SBI_OK)
> +               goto done;
> +
>         if ((start == 0 && size == 0) || (size == SBI_TLB_FLUSH_ALL)) {
>                 __sbi_hfence_vvma_asid(asid);
>                 goto done;
> @@ -133,6 +149,10 @@ static void sbi_tlb_local_hfence_gvma_vmid(struct sbi_tlb_info *tinfo)
>
>         sbi_pmu_ctr_incr_fw(SBI_PMU_FW_HFENCE_GVMA_VMID_RCVD);
>
> +       if (sbi_platform_local_hfence_gvma_vmid(
> +                       sbi_platform_thishart_ptr(), tinfo) == SBI_OK)
> +               return;
> +
>         if ((start == 0 && size == 0) || (size == SBI_TLB_FLUSH_ALL)) {
>                 __sbi_hfence_gvma_vmid(vmid);
>                 return;
> @@ -152,6 +172,10 @@ static void sbi_tlb_local_sfence_vma_asid(struct sbi_tlb_info *tinfo)
>
>         sbi_pmu_ctr_incr_fw(SBI_PMU_FW_SFENCE_VMA_ASID_RCVD);
>
> +       if (sbi_platform_local_sfence_vma_asid(
> +                       sbi_platform_thishart_ptr(), tinfo) == SBI_OK)
> +               return;
> +
>         /* Flush entire MM context for a given ASID */
>         if ((start == 0 && size == 0) || (size == SBI_TLB_FLUSH_ALL)) {
>                 __asm__ __volatile__("sfence.vma x0, %0"
> @@ -173,6 +197,10 @@ static void sbi_tlb_local_fence_i(struct sbi_tlb_info *tinfo)
>  {
>         sbi_pmu_ctr_incr_fw(SBI_PMU_FW_FENCE_I_RECVD);
>
> +       if (sbi_platform_local_fence_i(
> +                       sbi_platform_thishart_ptr(), tinfo) == SBI_OK)
> +               return;
> +
>         __asm__ __volatile("fence.i");
>  }
>
> 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..86793ab1 100644
> --- a/platform/generic/thead/thead-generic.c
> +++ b/platform/generic/thead/thead-generic.c
> @@ -13,6 +13,7 @@
>  #include <sbi/sbi_platform.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 {
> @@ -39,6 +40,20 @@ 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)
> +{
> +       __asm__ __volatile__("sfence.vma");
> +}
> +
> +static void thead_jtlb_local_sfence_vvma_asid(struct sbi_tlb_info *tinfo)
> +{
> +       /* 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)
>  {
> @@ -49,6 +64,11 @@ static int thead_generic_platform_init(const void *fdt, int nodeoff,
>         if (quirks->errata & THEAD_QUIRK_ERRATA_THEAD_PMU)
>                 generic_platform_ops.extensions_init = thead_pmu_extensions_init;
>
> +       if (quirks->errata &THEAD_QUIRK_ERRATA_JTLB) {
> +               generic_platform_ops.local_sfence_vma = thead_jtlb_local_sfence_vma;
> +               generic_platform_ops.local_sfence_vma_asid = thead_jtlb_local_sfence_vvma_asid;
> +       }
> +
>         return 0;
>  }
>
> @@ -60,13 +80,17 @@ 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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