[PATCH v2] lib: sbi: Enable Ssqosid Ext using mstateen0

[Anup Patel]

On Thu, Nov 6, 2025 at 5:44 PM <cp0613 at linux.alibaba.com> wrote:
>
> From: Chen Pei <cp0613 at linux.alibaba.com>
>
> The QoS Identifiers extension (Ssqosid) introduces the srmcfg register,
> which configures a hart with two identifiers: a Resource Control ID
> (RCID) and a Monitoring Counter ID (MCID). These identifiers accompany
> each request issued by the hart to shared resource controllers.
>
> If extension Smstateen is implemented together with Ssqosid, then
> Ssqosid also requires the SRMCFG bit in mstateen0 to be implemented. If
> mstateen0.SRMCFG is 0, attempts to access srmcfg in privilege modes less
> privileged than M-mode raise an illegal-instruction exception. If
> mstateen0.SRMCFG is 1 or if extension Smstateen is not implemented,
> attempts to access srmcfg when V=1 raise a virtual-instruction exception.
>
> This extension can be found in the RISC-V Instruction Set Manual:
> https://github.com/riscv/riscv-isa-manual
>
> Signed-off-by: Chen Pei <cp0613 at linux.alibaba.com>
> ---
>  include/sbi/riscv_encoding.h | 5 +++++
>  include/sbi/sbi_hart.h       | 2 ++
>  lib/sbi/sbi_domain_context.c | 6 +++++-
>  lib/sbi/sbi_hart.c           | 6 ++++++
>  4 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/include/sbi/riscv_encoding.h b/include/sbi/riscv_encoding.h
> index 61e4b635..b738e209 100644
> --- a/include/sbi/riscv_encoding.h
> +++ b/include/sbi/riscv_encoding.h
> @@ -378,6 +378,9 @@
>  #define CSR_SSTATEEN2                  0x10E
>  #define CSR_SSTATEEN3                  0x10F
>
> +/* Supervisor Resource Management Configuration CSRs */
> +#define CSR_SRMCFG                     0x181
> +
>  /* Machine-Level Control transfer records CSRs */
>  #define CSR_MCTRCTL                     0x34e
>
> @@ -849,6 +852,8 @@
>  #define SMSTATEEN0_FCSR                        (_ULL(1) << SMSTATEEN0_FCSR_SHIFT)
>  #define SMSTATEEN0_CTR_SHIFT           54
>  #define SMSTATEEN0_CTR                 (_ULL(1) << SMSTATEEN0_CTR_SHIFT)
> +#define SMSTATEEN0_SRMCFG_SHIFT                55
> +#define SMSTATEEN0_SRMCFG              (_ULL(1) << SMSTATEEN0_SRMCFG_SHIFT)
>  #define SMSTATEEN0_CONTEXT_SHIFT       57
>  #define SMSTATEEN0_CONTEXT             (_ULL(1) << SMSTATEEN0_CONTEXT_SHIFT)
>  #define SMSTATEEN0_IMSIC_SHIFT         58
> diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
> index e66dd52f..c51b0689 100644
> --- a/include/sbi/sbi_hart.h
> +++ b/include/sbi/sbi_hart.h
> @@ -79,6 +79,8 @@ enum sbi_hart_extensions {
>         SBI_HART_EXT_SMCTR,
>         /** HART has CTR S-mode CSRs */
>         SBI_HART_EXT_SSCTR,
> +       /** Hart has Ssqosid extension */
> +       SBI_HART_EXT_SSQOSID,
>         /** HART has Ssstateen extension **/
>         SBI_HART_EXT_SSSTATEEN,
>         /** Hart has Xsfcflushdlone extension */
> diff --git a/lib/sbi/sbi_domain_context.c b/lib/sbi/sbi_domain_context.c
> index 74ad25e8..b1b1c258 100644
> --- a/lib/sbi/sbi_domain_context.c
> +++ b/lib/sbi/sbi_domain_context.c
> @@ -45,6 +45,8 @@ struct hart_context {
>         unsigned long scounteren;
>         /** Supervisor environment configuration register */
>         unsigned long senvcfg;
> +       /** Supervisor resource management configuration register */
> +       unsigned long srmcfg;
>
>         /** Reference to the owning domain */
>         struct sbi_domain *dom;
> @@ -143,8 +145,10 @@ static int switch_to_next_domain_context(struct hart_context *ctx,
>         ctx->satp       = csr_swap(CSR_SATP, dom_ctx->satp);
>         if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_10)
>                 ctx->scounteren = csr_swap(CSR_SCOUNTEREN, dom_ctx->scounteren);
> -       if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_12)
> +       if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_12) {
>                 ctx->senvcfg    = csr_swap(CSR_SENVCFG, dom_ctx->senvcfg);

There needs to be an "if (sbi_hart_has_extension(scratch,
SBI_HART_EXT_SSQOSID))"
over here before swapping SRMCFG so that csr is accessed only when
extension is present.

> +               ctx->srmcfg             = csr_swap(CSR_SRMCFG, dom_ctx->srmcfg);
> +       }
>
>         /* Save current trap state and restore target domain's trap state */
>         trap_ctx = sbi_trap_get_context(scratch);
> diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
> index a91703b4..549906f6 100644
> --- a/lib/sbi/sbi_hart.c
> +++ b/lib/sbi/sbi_hart.c
> @@ -112,6 +112,11 @@ static void mstatus_init(struct sbi_scratch *scratch)
>                 else
>                         mstateen_val &= ~SMSTATEEN0_CTR;
>
> +               if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SSQOSID))
> +                       mstateen_val |= (SMSTATEEN0_SRMCFG);
> +               else
> +                       mstateen_val &= ~(SMSTATEEN0_SRMCFG);
> +
>                 csr_write64(CSR_MSTATEEN0, mstateen_val);
>                 csr_write64(CSR_MSTATEEN1, SMSTATEEN_STATEN);
>                 csr_write64(CSR_MSTATEEN2, SMSTATEEN_STATEN);
> @@ -685,6 +690,7 @@ const struct sbi_hart_ext_data sbi_hart_ext[] = {
>         __SBI_HART_EXT_DATA(ssdbltrp, SBI_HART_EXT_SSDBLTRP),
>         __SBI_HART_EXT_DATA(smctr, SBI_HART_EXT_SMCTR),
>         __SBI_HART_EXT_DATA(ssctr, SBI_HART_EXT_SSCTR),
> +       __SBI_HART_EXT_DATA(ssqosid, SBI_HART_EXT_SSQOSID),
>         __SBI_HART_EXT_DATA(ssstateen, SBI_HART_EXT_SSSTATEEN),
>         __SBI_HART_EXT_DATA(xsfcflushdlone, SBI_HART_EXT_XSIFIVE_CFLUSH_D_L1),
>         __SBI_HART_EXT_DATA(xsfcease, SBI_HART_EXT_XSIFIVE_CEASE),
> --
> 2.50.1
>

Regards,
Anup