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    Subject[PATCH v7 08/10] RISC-V: Add SBI HSM extension
    Date
    SBI specification defines HSM extension that allows to start/stop a hart
    by a supervisor anytime. The specification is available at

    https://github.com/riscv/riscv-sbi-doc/blob/master/riscv-sbi.adoc

    Implement SBI HSM extension.

    Signed-off-by: Atish Patra <atish.patra@wdc.com>
    ---
    arch/riscv/include/asm/sbi.h | 22 ++++++++++++++++
    arch/riscv/kernel/sbi.c | 51 ++++++++++++++++++++++++++++++++++++
    2 files changed, 73 insertions(+)

    diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
    index d55d8090ab5c..bed6fa26ec84 100644
    --- a/arch/riscv/include/asm/sbi.h
    +++ b/arch/riscv/include/asm/sbi.h
    @@ -26,6 +26,7 @@ enum sbi_ext_id {
    SBI_EXT_TIME = 0x54494D45,
    SBI_EXT_IPI = 0x735049,
    SBI_EXT_RFENCE = 0x52464E43,
    + SBI_EXT_HSM = 0x48534D,
    };

    enum sbi_ext_base_fid {
    @@ -56,6 +57,12 @@ enum sbi_ext_rfence_fid {
    SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA_ASID,
    };

    +enum sbi_ext_hsm_fid {
    + SBI_EXT_HSM_HART_START = 0,
    + SBI_EXT_HSM_HART_STOP,
    + SBI_EXT_HSM_HART_STATUS,
    +};
    +
    #define SBI_SPEC_VERSION_DEFAULT 0x1
    #define SBI_SPEC_VERSION_MAJOR_SHIFT 24
    #define SBI_SPEC_VERSION_MAJOR_MASK 0x7f
    @@ -70,6 +77,7 @@ enum sbi_ext_rfence_fid {
    #define SBI_ERR_INVALID_ADDRESS -5

    extern unsigned long sbi_spec_version;
    +extern bool sbi_hsm_avail;
    struct sbiret {
    long error;
    long value;
    @@ -110,8 +118,18 @@ int sbi_remote_hfence_vvma_asid(const unsigned long *hart_mask,
    unsigned long start,
    unsigned long size,
    unsigned long asid);
    +int sbi_hsm_hart_start(unsigned long hartid, unsigned long saddr,
    + unsigned long priv);
    +int sbi_hsm_hart_stop(void);
    +int sbi_hsm_hart_get_status(unsigned long hartid);
    +
    int sbi_probe_extension(int ext);

    +static inline bool sbi_hsm_is_available(void)
    +{
    + return sbi_hsm_avail;
    +}
    +
    /* Check if current SBI specification version is 0.1 or not */
    static inline int sbi_spec_is_0_1(void)
    {
    @@ -137,5 +155,9 @@ void sbi_clear_ipi(void);
    void sbi_send_ipi(const unsigned long *hart_mask);
    void sbi_remote_fence_i(const unsigned long *hart_mask);
    void sbi_init(void);
    +static inline bool sbi_hsm_is_available(void)
    +{
    + return false;
    +}
    #endif /* CONFIG_RISCV_SBI */
    #endif /* _ASM_RISCV_SBI_H */
    diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
    index 3c34aba30f6f..9bdc9801784d 100644
    --- a/arch/riscv/kernel/sbi.c
    +++ b/arch/riscv/kernel/sbi.c
    @@ -12,6 +12,8 @@

    /* default SBI version is 0.1 */
    unsigned long sbi_spec_version = SBI_SPEC_VERSION_DEFAULT;
    +bool sbi_hsm_avail;
    +
    EXPORT_SYMBOL(sbi_spec_version);

    static void (*__sbi_set_timer)(uint64_t stime);
    @@ -496,6 +498,54 @@ static void sbi_power_off(void)
    sbi_shutdown();
    }

    +int sbi_hsm_hart_stop(void)
    +{
    + struct sbiret ret;
    +
    + ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STOP, 0, 0, 0, 0, 0, 0);
    +
    + if (!ret.error)
    + return ret.value;
    + else
    + return sbi_err_map_linux_errno(ret.error);
    +}
    +EXPORT_SYMBOL(sbi_hsm_hart_stop);
    +
    +int sbi_hsm_hart_start(unsigned long hartid, unsigned long saddr,
    + unsigned long priv)
    +{
    + struct sbiret ret;
    +
    + ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_START,
    + hartid, saddr, priv, 0, 0, 0);
    + if (!ret.error)
    + return ret.value;
    + else
    + return sbi_err_map_linux_errno(ret.error);
    +}
    +EXPORT_SYMBOL(sbi_hsm_hart_start);
    +
    +int sbi_hsm_hart_get_status(unsigned long hartid)
    +{
    + struct sbiret ret;
    +
    + ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STATUS,
    + hartid, 0, 0, 0, 0, 0);
    + if (!ret.error)
    + return ret.value;
    + else
    + return sbi_err_map_linux_errno(ret.error);
    +}
    +EXPORT_SYMBOL(sbi_hsm_hart_get_status);
    +
    +void __init sbi_hsm_ext_init(void)
    +{
    + if (sbi_probe_extension(SBI_EXT_HSM) > 0) {
    + pr_info("SBI v0.2 HSM extension detected\n");
    + sbi_hsm_avail = true;
    + }
    +}
    +
    int __init sbi_init(void)
    {
    int ret;
    @@ -532,5 +582,6 @@ int __init sbi_init(void)
    __sbi_rfence = __sbi_rfence_v01;
    }

    + sbi_hsm_ext_init();
    return 0;
    }
    --
    2.24.0
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