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Re: [PATCH v11 1/5] target/riscv: Add smstateen support


From: Alistair Francis
Subject: Re: [PATCH v11 1/5] target/riscv: Add smstateen support
Date: Thu, 10 Nov 2022 09:16:14 +1000

On Sun, Oct 16, 2022 at 10:51 PM Mayuresh Chitale
<mchitale@ventanamicro.com> wrote:
>
> Smstateen extension specifies a mechanism to close
> the potential covert channels that could cause security issues.
>
> This patch adds the CSRs defined in the specification and
> the corresponding predicates and read/write functions.
>
> Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
> Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/cpu.h      |   4 +
>  target/riscv/cpu_bits.h |  37 +++++
>  target/riscv/csr.c      | 316 ++++++++++++++++++++++++++++++++++++++++
>  target/riscv/machine.c  |  21 +++
>  4 files changed, 378 insertions(+)
>
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index 3a9e25053f..040ed13675 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -366,6 +366,9 @@ struct CPUArchState {
>
>      /* CSRs for execution enviornment configuration */
>      uint64_t menvcfg;
> +    uint64_t mstateen[SMSTATEEN_MAX_COUNT];
> +    uint64_t hstateen[SMSTATEEN_MAX_COUNT];
> +    uint64_t sstateen[SMSTATEEN_MAX_COUNT];
>      target_ulong senvcfg;
>      uint64_t henvcfg;
>  #endif
> @@ -441,6 +444,7 @@ struct RISCVCPUConfig {
>      bool ext_ifencei;
>      bool ext_icsr;
>      bool ext_zihintpause;
> +    bool ext_smstateen;
>      bool ext_sstc;
>      bool ext_svinval;
>      bool ext_svnapot;
> diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
> index d8f5f0abed..8b0d7e20ea 100644
> --- a/target/riscv/cpu_bits.h
> +++ b/target/riscv/cpu_bits.h
> @@ -197,6 +197,12 @@
>  /* Supervisor Configuration CSRs */
>  #define CSR_SENVCFG         0x10A
>
> +/* Supervisor state CSRs */
> +#define CSR_SSTATEEN0       0x10C
> +#define CSR_SSTATEEN1       0x10D
> +#define CSR_SSTATEEN2       0x10E
> +#define CSR_SSTATEEN3       0x10F
> +
>  /* Supervisor Trap Handling */
>  #define CSR_SSCRATCH        0x140
>  #define CSR_SEPC            0x141
> @@ -244,6 +250,16 @@
>  #define CSR_HENVCFG         0x60A
>  #define CSR_HENVCFGH        0x61A
>
> +/* Hypervisor state CSRs */
> +#define CSR_HSTATEEN0       0x60C
> +#define CSR_HSTATEEN0H      0x61C
> +#define CSR_HSTATEEN1       0x60D
> +#define CSR_HSTATEEN1H      0x61D
> +#define CSR_HSTATEEN2       0x60E
> +#define CSR_HSTATEEN2H      0x61E
> +#define CSR_HSTATEEN3       0x60F
> +#define CSR_HSTATEEN3H      0x61F
> +
>  /* Virtual CSRs */
>  #define CSR_VSSTATUS        0x200
>  #define CSR_VSIE            0x204
> @@ -289,6 +305,27 @@
>  #define CSR_MENVCFG         0x30A
>  #define CSR_MENVCFGH        0x31A
>
> +/* Machine state CSRs */
> +#define CSR_MSTATEEN0       0x30C
> +#define CSR_MSTATEEN0H      0x31C
> +#define CSR_MSTATEEN1       0x30D
> +#define CSR_MSTATEEN1H      0x31D
> +#define CSR_MSTATEEN2       0x30E
> +#define CSR_MSTATEEN2H      0x31E
> +#define CSR_MSTATEEN3       0x30F
> +#define CSR_MSTATEEN3H      0x31F
> +
> +/* Common defines for all smstateen */
> +#define SMSTATEEN_MAX_COUNT 4
> +#define SMSTATEEN0_CS       (1ULL << 0)
> +#define SMSTATEEN0_FCSR     (1ULL << 1)
> +#define SMSTATEEN0_HSCONTXT (1ULL << 57)
> +#define SMSTATEEN0_IMSIC    (1ULL << 58)
> +#define SMSTATEEN0_AIA      (1ULL << 59)
> +#define SMSTATEEN0_SVSLCT   (1ULL << 60)
> +#define SMSTATEEN0_HSENVCFG (1ULL << 62)
> +#define SMSTATEEN_STATEEN   (1ULL << 63)
> +
>  /* Enhanced Physical Memory Protection (ePMP) */
>  #define CSR_MSECCFG         0x747
>  #define CSR_MSECCFGH        0x757
> diff --git a/target/riscv/csr.c b/target/riscv/csr.c
> index 5c9a7ee287..c861424e85 100644
> --- a/target/riscv/csr.c
> +++ b/target/riscv/csr.c
> @@ -283,6 +283,72 @@ static RISCVException umode32(CPURISCVState *env, int 
> csrno)
>      return umode(env, csrno);
>  }
>
> +static RISCVException mstateen(CPURISCVState *env, int csrno)
> +{
> +    CPUState *cs = env_cpu(env);
> +    RISCVCPU *cpu = RISCV_CPU(cs);
> +
> +    if (!cpu->cfg.ext_smstateen) {
> +        return RISCV_EXCP_ILLEGAL_INST;
> +    }
> +
> +    return any(env, csrno);
> +}
> +
> +static RISCVException hstateen_pred(CPURISCVState *env, int csrno, int base)
> +{
> +    CPUState *cs = env_cpu(env);
> +    RISCVCPU *cpu = RISCV_CPU(cs);
> +
> +    if (!cpu->cfg.ext_smstateen) {
> +        return RISCV_EXCP_ILLEGAL_INST;
> +    }
> +
> +    if (env->priv < PRV_M) {
> +        if (!(env->mstateen[csrno - base] & SMSTATEEN_STATEEN)) {
> +            return RISCV_EXCP_ILLEGAL_INST;
> +        }
> +    }
> +
> +    return hmode(env, csrno);
> +}
> +
> +static RISCVException hstateen(CPURISCVState *env, int csrno)
> +{
> +    return hstateen_pred(env, csrno, CSR_HSTATEEN0);
> +}
> +
> +static RISCVException hstateenh(CPURISCVState *env, int csrno)
> +{
> +    return hstateen_pred(env, csrno, CSR_HSTATEEN0H);
> +}
> +
> +static RISCVException sstateen(CPURISCVState *env, int csrno)
> +{
> +    bool virt = riscv_cpu_virt_enabled(env);
> +    int index = csrno - CSR_SSTATEEN0;
> +    CPUState *cs = env_cpu(env);
> +    RISCVCPU *cpu = RISCV_CPU(cs);
> +
> +    if (!cpu->cfg.ext_smstateen) {
> +        return RISCV_EXCP_ILLEGAL_INST;
> +    }
> +
> +    if (env->priv < PRV_M) {
> +        if (!(env->mstateen[index] & SMSTATEEN_STATEEN)) {
> +            return RISCV_EXCP_ILLEGAL_INST;
> +        }
> +
> +        if (virt) {
> +            if (!(env->hstateen[index] & SMSTATEEN_STATEEN)) {
> +                return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
> +            }
> +        }
> +    }
> +
> +    return smode(env, csrno);
> +}
> +
>  /* Checks if PointerMasking registers could be accessed */
>  static RISCVException pointer_masking(CPURISCVState *env, int csrno)
>  {
> @@ -1861,6 +1927,197 @@ static RISCVException write_henvcfgh(CPURISCVState 
> *env, int csrno,
>      return RISCV_EXCP_NONE;
>  }
>
> +static RISCVException read_mstateen(CPURISCVState *env, int csrno,
> +                                    target_ulong *val)
> +{
> +    *val = env->mstateen[csrno - CSR_MSTATEEN0];
> +
> +    return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException write_mstateen(CPURISCVState *env, int csrno,
> +                                     uint64_t wr_mask, target_ulong new_val)
> +{
> +    uint64_t *reg;
> +
> +    reg = &env->mstateen[csrno - CSR_MSTATEEN0];
> +    *reg = (*reg & ~wr_mask) | (new_val & wr_mask);
> +
> +    return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException write_mstateen0(CPURISCVState *env, int csrno,
> +                                      target_ulong new_val)
> +{
> +    uint64_t wr_mask = SMSTATEEN_STATEEN;
> +
> +    return write_mstateen(env, csrno, wr_mask, new_val);
> +}
> +
> +static RISCVException write_mstateen_1_3(CPURISCVState *env, int csrno,
> +                                      target_ulong new_val)
> +{
> +    return write_mstateen(env, csrno, SMSTATEEN_STATEEN, new_val);
> +}
> +
> +static RISCVException read_mstateenh(CPURISCVState *env, int csrno,
> +                                      target_ulong *val)
> +{
> +    *val = env->mstateen[csrno - CSR_MSTATEEN0H] >> 32;
> +
> +    return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException write_mstateenh(CPURISCVState *env, int csrno,
> +                                      uint64_t wr_mask, target_ulong new_val)
> +{
> +    uint64_t *reg, val;
> +
> +    reg = &env->mstateen[csrno - CSR_MSTATEEN0H];
> +    val = (uint64_t)new_val << 32;
> +    val |= *reg & 0xFFFFFFFF;
> +    *reg = (*reg & ~wr_mask) | (val & wr_mask);
> +
> +    return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException write_mstateen0h(CPURISCVState *env, int csrno,
> +                                      target_ulong new_val)
> +{
> +    uint64_t wr_mask = SMSTATEEN_STATEEN;
> +
> +    return write_mstateenh(env, csrno, wr_mask, new_val);
> +}
> +
> +static RISCVException write_mstateenh_1_3(CPURISCVState *env, int csrno,
> +                                      target_ulong new_val)
> +{
> +    return write_mstateenh(env, csrno, SMSTATEEN_STATEEN, new_val);
> +}
> +
> +static RISCVException read_hstateen(CPURISCVState *env, int csrno,
> +                                    target_ulong *val)
> +{
> +    int index = csrno - CSR_HSTATEEN0;
> +
> +    *val = env->hstateen[index] & env->mstateen[index];
> +
> +    return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException write_hstateen(CPURISCVState *env, int csrno,
> +                                     uint64_t mask, target_ulong new_val)
> +{
> +    int index = csrno - CSR_HSTATEEN0;
> +    uint64_t *reg, wr_mask;
> +
> +    reg = &env->hstateen[index];
> +    wr_mask = env->mstateen[index] & mask;
> +    *reg = (*reg & ~wr_mask) | (new_val & wr_mask);
> +
> +    return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException write_hstateen0(CPURISCVState *env, int csrno,
> +                                      target_ulong new_val)
> +{
> +    uint64_t wr_mask = SMSTATEEN_STATEEN;
> +
> +    return write_hstateen(env, csrno, wr_mask, new_val);
> +}
> +
> +static RISCVException write_hstateen_1_3(CPURISCVState *env, int csrno,
> +                                      target_ulong new_val)
> +{
> +    return write_hstateen(env, csrno, SMSTATEEN_STATEEN, new_val);
> +}
> +
> +static RISCVException read_hstateenh(CPURISCVState *env, int csrno,
> +                                     target_ulong *val)
> +{
> +    int index = csrno - CSR_HSTATEEN0H;
> +
> +    *val = (env->hstateen[index] >> 32) & (env->mstateen[index] >> 32);
> +
> +    return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException write_hstateenh(CPURISCVState *env, int csrno,
> +                                      uint64_t mask, target_ulong new_val)
> +{
> +    int index = csrno - CSR_HSTATEEN0H;
> +    uint64_t *reg, wr_mask, val;
> +
> +    reg = &env->hstateen[index];
> +    val = (uint64_t)new_val << 32;
> +    val |= *reg & 0xFFFFFFFF;
> +    wr_mask = env->mstateen[index] & mask;
> +    *reg = (*reg & ~wr_mask) | (val & wr_mask);
> +
> +    return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException write_hstateen0h(CPURISCVState *env, int csrno,
> +                                       target_ulong new_val)
> +{
> +    uint64_t wr_mask = SMSTATEEN_STATEEN;
> +
> +    return write_hstateenh(env, csrno, wr_mask, new_val);
> +}
> +
> +static RISCVException write_hstateenh_1_3(CPURISCVState *env, int csrno,
> +                                       target_ulong new_val)
> +{
> +    return write_hstateenh(env, csrno, SMSTATEEN_STATEEN, new_val);
> +}
> +
> +static RISCVException read_sstateen(CPURISCVState *env, int csrno,
> +                                    target_ulong *val)
> +{
> +    bool virt = riscv_cpu_virt_enabled(env);
> +    int index = csrno - CSR_SSTATEEN0;
> +
> +    *val = env->sstateen[index] & env->mstateen[index];
> +    if (virt) {
> +        *val &= env->hstateen[index];
> +    }
> +
> +    return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException write_sstateen(CPURISCVState *env, int csrno,
> +                                     uint64_t mask, target_ulong new_val)
> +{
> +    bool virt = riscv_cpu_virt_enabled(env);
> +    int index = csrno - CSR_SSTATEEN0;
> +    uint64_t wr_mask;
> +    uint64_t *reg;
> +
> +    wr_mask = env->mstateen[index] & mask;
> +    if (virt) {
> +        wr_mask &= env->hstateen[index];
> +    }
> +
> +    reg = &env->sstateen[index];
> +    *reg = (*reg & ~wr_mask) | (new_val & wr_mask);
> +
> +    return RISCV_EXCP_NONE;
> +}
> +
> +static RISCVException write_sstateen0(CPURISCVState *env, int csrno,
> +                                      target_ulong new_val)
> +{
> +    uint64_t wr_mask = SMSTATEEN_STATEEN;
> +
> +    return write_sstateen(env, csrno, wr_mask, new_val);
> +}
> +
> +static RISCVException write_sstateen_1_3(CPURISCVState *env, int csrno,
> +                                      target_ulong new_val)
> +{
> +    return write_sstateen(env, csrno, SMSTATEEN_STATEEN, new_val);
> +}
> +
>  static RISCVException rmw_mip64(CPURISCVState *env, int csrno,
>                                  uint64_t *ret_val,
>                                  uint64_t new_val, uint64_t wr_mask)
> @@ -3744,6 +4001,65 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
>      [CSR_HENVCFGH] = { "henvcfgh", hmode32, read_henvcfgh, write_henvcfgh,
>                         .min_priv_ver = PRIV_VERSION_1_12_0              },
>
> +    /* Smstateen extension CSRs */
> +    [CSR_MSTATEEN0] = { "mstateen0", mstateen, read_mstateen, 
> write_mstateen0,
> +                        .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_MSTATEEN0H] = { "mstateen0h", mstateen, read_mstateenh,
> +                          write_mstateen0h,
> +                         .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_MSTATEEN1] = { "mstateen1", mstateen, read_mstateen,
> +                        write_mstateen_1_3,
> +                        .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_MSTATEEN1H] = { "mstateen1h", mstateen, read_mstateenh,
> +                         write_mstateenh_1_3,
> +                         .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_MSTATEEN2] = { "mstateen2", mstateen, read_mstateen,
> +                        write_mstateen_1_3,
> +                        .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_MSTATEEN2H] = { "mstateen2h", mstateen, read_mstateenh,
> +                         write_mstateenh_1_3,
> +                         .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_MSTATEEN3] = { "mstateen3", mstateen, read_mstateen,
> +                        write_mstateen_1_3,
> +                        .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_MSTATEEN3H] = { "mstateen3h", mstateen, read_mstateenh,
> +                         write_mstateenh_1_3,
> +                         .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_HSTATEEN0] = { "hstateen0", hstateen, read_hstateen, 
> write_hstateen0,
> +                        .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_HSTATEEN0H] = { "hstateen0h", hstateenh, read_hstateenh,
> +                         write_hstateen0h,
> +                         .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_HSTATEEN1] = { "hstateen1", hstateen, read_hstateen,
> +                        write_hstateen_1_3,
> +                        .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_HSTATEEN1H] = { "hstateen1h", hstateenh, read_hstateenh,
> +                         write_hstateenh_1_3,
> +                         .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_HSTATEEN2] = { "hstateen2", hstateen, read_hstateen,
> +                        write_hstateen_1_3,
> +                        .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_HSTATEEN2H] = { "hstateen2h", hstateenh, read_hstateenh,
> +                         write_hstateenh_1_3,
> +                         .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_HSTATEEN3] = { "hstateen3", hstateen, read_hstateen,
> +                        write_hstateen_1_3,
> +                        .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_HSTATEEN3H] = { "hstateen3h", hstateenh, read_hstateenh,
> +                         write_hstateenh_1_3,
> +                         .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_SSTATEEN0] = { "sstateen0", sstateen, read_sstateen, 
> write_sstateen0,
> +                        .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_SSTATEEN1] = { "sstateen1", sstateen, read_sstateen,
> +                        write_sstateen_1_3,
> +                        .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_SSTATEEN2] = { "sstateen2", sstateen, read_sstateen,
> +                        write_sstateen_1_3,
> +                        .min_priv_ver = PRIV_VERSION_1_12_0 },
> +    [CSR_SSTATEEN3] = { "sstateen3", sstateen, read_sstateen,
> +                        write_sstateen_1_3,
> +                        .min_priv_ver = PRIV_VERSION_1_12_0 },
> +
>      /* Supervisor Trap Setup */
>      [CSR_SSTATUS]    = { "sstatus",    smode, read_sstatus,    write_sstatus,
>                           NULL,                read_sstatus_i128              
>  },
> diff --git a/target/riscv/machine.c b/target/riscv/machine.c
> index c2a94a82b3..e687f9fce0 100644
> --- a/target/riscv/machine.c
> +++ b/target/riscv/machine.c
> @@ -253,6 +253,26 @@ static int riscv_cpu_post_load(void *opaque, int 
> version_id)
>      return 0;
>  }
>
> +static bool smstateen_needed(void *opaque)
> +{
> +    RISCVCPU *cpu = opaque;
> +
> +    return cpu->cfg.ext_smstateen;
> +}
> +
> +static const VMStateDescription vmstate_smstateen = {
> +    .name = "cpu/smtateen",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .needed = smstateen_needed,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_UINT64_ARRAY(env.mstateen, RISCVCPU, 4),
> +        VMSTATE_UINT64_ARRAY(env.hstateen, RISCVCPU, 4),
> +        VMSTATE_UINT64_ARRAY(env.sstateen, RISCVCPU, 4),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
>  static bool envcfg_needed(void *opaque)
>  {
>      RISCVCPU *cpu = opaque;
> @@ -364,6 +384,7 @@ const VMStateDescription vmstate_riscv_cpu = {
>          &vmstate_kvmtimer,
>          &vmstate_envcfg,
>          &vmstate_debug,
> +        &vmstate_smstateen,
>          NULL
>      }
>  };
> --
> 2.25.1
>
>



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