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[RFC PATCH v5 1/4] target/riscv: Add smstateen support


From: Mayuresh Chitale
Subject: [RFC PATCH v5 1/4] target/riscv: Add smstateen support
Date: Fri, 3 Jun 2022 21:34:22 +0530

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>
---
 target/riscv/cpu.c      |   2 +
 target/riscv/cpu.h      |   4 +
 target/riscv/cpu_bits.h |  36 +++++++
 target/riscv/csr.c      | 210 ++++++++++++++++++++++++++++++++++++++++
 target/riscv/machine.c  |  21 ++++
 5 files changed, 273 insertions(+)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index e6e878ceb3..2d65ccd90f 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -913,6 +913,7 @@ static Property riscv_cpu_properties[] = {
     DEFINE_PROP_BOOL("mmu", RISCVCPU, cfg.mmu, true),
     DEFINE_PROP_BOOL("pmp", RISCVCPU, cfg.pmp, true),
     DEFINE_PROP_BOOL("debug", RISCVCPU, cfg.debug, true),
+    DEFINE_PROP_BOOL("smstateen", RISCVCPU, cfg.ext_smstateen, false),
 
     DEFINE_PROP_STRING("priv_spec", RISCVCPU, cfg.priv_spec),
     DEFINE_PROP_STRING("vext_spec", RISCVCPU, cfg.vext_spec),
@@ -1104,6 +1105,7 @@ static void riscv_isa_string_ext(RISCVCPU *cpu, char 
**isa_str, int max_str_len)
         ISA_EDATA_ENTRY(zve64f, ext_zve64f),
         ISA_EDATA_ENTRY(zhinx, ext_zhinx),
         ISA_EDATA_ENTRY(zhinxmin, ext_zhinxmin),
+        ISA_EDATA_ENTRY(smstateen, ext_smstateen),
         ISA_EDATA_ENTRY(svinval, ext_svinval),
         ISA_EDATA_ENTRY(svnapot, ext_svnapot),
         ISA_EDATA_ENTRY(svpbmt, ext_svpbmt),
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index f08c3e8813..1c269b77bd 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -327,6 +327,9 @@ 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
@@ -411,6 +414,7 @@ struct RISCVCPUConfig {
     bool ext_zhinxmin;
     bool ext_zve32f;
     bool ext_zve64f;
+    bool ext_smstateen;
 
     uint32_t mvendorid;
     uint64_t marchid;
diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
index 4a55c6a709..2a3ef26d21 100644
--- a/target/riscv/cpu_bits.h
+++ b/target/riscv/cpu_bits.h
@@ -208,6 +208,12 @@
 /* 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
@@ -257,6 +263,16 @@
 #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
@@ -304,6 +320,26 @@
 #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       0
+#define SMSTATEEN0_FCSR     0
+#define SMSTATEEN0_IMSIC    58
+#define SMSTATEEN0_AIA      59
+#define SMSTATEEN0_SVSLCT   60
+#define SMSTATEEN0_HSENVCFG 62
+#define SMSTATEEN_STATEN    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 409a209f14..324fefce59 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -247,6 +247,42 @@ static RISCVException hmode32(CPURISCVState *env, int 
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(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 hmode(env, csrno);
+}
+
+static RISCVException sstateen(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 smode(env, csrno);
+}
+
 /* Checks if PointerMasking registers could be accessed */
 static RISCVException pointer_masking(CPURISCVState *env, int csrno)
 {
@@ -1574,6 +1610,129 @@ static RISCVException write_henvcfgh(CPURISCVState 
*env, int csrno,
     return RISCV_EXCP_NONE;
 }
 
+static inline void write_smstateen(CPURISCVState *env, uint64_t *reg,
+                                   uint64_t wr_mask, uint64_t new_val)
+{
+    *reg = (*reg & ~wr_mask) | (new_val & wr_mask);
+}
+
+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,
+                                     target_ulong new_val)
+{
+    uint64_t *reg;
+    uint64_t wr_mask = 1UL << SMSTATEEN_STATEN;
+
+    reg = &env->mstateen[csrno - CSR_MSTATEEN0];
+    write_smstateen(env, reg, wr_mask, new_val);
+
+    return RISCV_EXCP_NONE;
+}
+
+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,
+                                      target_ulong new_val)
+{
+    uint64_t *reg;
+    uint64_t val;
+    uint64_t wr_mask = 1UL << SMSTATEEN_STATEN;
+
+    reg = &env->mstateen[csrno - CSR_MSTATEEN0H];
+    val = (uint64_t)new_val << 32;
+    val |= *reg & 0xFFFFFFFF;
+    write_smstateen(env, reg, wr_mask, val);
+
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_hstateen(CPURISCVState *env, int csrno,
+                                    target_ulong *val)
+{
+    *val = env->hstateen[csrno - CSR_HSTATEEN0];
+
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_hstateen(CPURISCVState *env, int csrno,
+                                     target_ulong new_val)
+{
+    uint64_t *reg;
+    uint64_t wr_mask = 1UL << SMSTATEEN_STATEN;
+    int index = csrno - CSR_HSTATEEN0;
+
+    reg = &env->hstateen[index];
+    wr_mask &= env->mstateen[index];
+    write_smstateen(env, reg, wr_mask, new_val);
+
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_hstateenh(CPURISCVState *env, int csrno,
+                                     target_ulong *val)
+{
+    *val = env->hstateen[csrno - CSR_HSTATEEN0H] >> 32;
+
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_hstateenh(CPURISCVState *env, int csrno,
+                                      target_ulong new_val)
+{
+    uint64_t *reg;
+    uint64_t val;
+    uint64_t wr_mask = 1UL << SMSTATEEN_STATEN;
+    int index = csrno - CSR_HSTATEEN0H;
+
+    reg = &env->hstateen[index];
+    val = (uint64_t)new_val << 32;
+    val |= *reg & 0xFFFFFFFF;
+    wr_mask &= env->mstateen[index];
+
+    write_smstateen(env, reg, wr_mask, val);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_sstateen(CPURISCVState *env, int csrno,
+                                    target_ulong *val)
+{
+    *val = env->sstateen[csrno - CSR_SSTATEEN0];
+
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_sstateen(CPURISCVState *env, int csrno,
+                                     target_ulong new_val)
+{
+    uint64_t *reg;
+    uint64_t wr_mask = 0;
+    int index = csrno - CSR_SSTATEEN0;
+    bool virt = riscv_cpu_virt_enabled(env);
+
+    reg = &env->sstateen[index];
+    if (virt) {
+        wr_mask &= env->mstateen[index];
+    } else {
+        wr_mask &= env->hstateen[index];
+    }
+    write_smstateen(env, reg, wr_mask, new_val);
+
+    return RISCV_EXCP_NONE;
+}
+
 static RISCVException rmw_mip64(CPURISCVState *env, int csrno,
                                 uint64_t *ret_val,
                                 uint64_t new_val, uint64_t wr_mask)
@@ -3441,6 +3600,57 @@ 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_mstateen,
+                         .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_MSTATEEN0H] = { "mstateen0h", mstateen, read_mstateenh,
+                          write_mstateenh,
+                          .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_MSTATEEN1] = { "mstateen1", mstateen, read_mstateen, write_mstateen,
+                         .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_MSTATEEN1H] = { "mstateen1h", mstateen, read_mstateenh,
+                          write_mstateenh,
+                          .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_MSTATEEN2] = { "mstateen2", mstateen, read_mstateen, write_mstateen,
+                         .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_MSTATEEN2H] = { "mstateen2h", mstateen, read_mstateenh,
+                          write_mstateenh,
+                          .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_MSTATEEN3] = { "mstateen3", mstateen, read_mstateen, write_mstateen,
+                         .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_MSTATEEN3H] = { "mstateen3h", mstateen, read_mstateenh,
+                          write_mstateenh,
+                          .min_priv_ver = PRIV_VERSION_1_12_0 },
+
+    [CSR_HSTATEEN0] = { "hstateen0", hstateen, read_hstateen, write_hstateen,
+                         .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_HSTATEEN0H] = { "hstateen0h", hstateen, read_hstateenh,
+                          write_hstateenh,
+                          .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_HSTATEEN1] = { "hstateen1", hstateen, read_hstateen, write_hstateen,
+                         .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_HSTATEEN1H] = { "hstateen1h", hstateen, read_hstateenh,
+                          write_hstateenh,
+                          .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_HSTATEEN2] = { "hstateen2", hstateen, read_hstateen, write_hstateen,
+                         .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_HSTATEEN2H] = { "hstateen2h", hstateen, read_hstateenh,
+                          write_hstateenh,
+                          .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_HSTATEEN3] = { "hstateen3", hstateen, read_hstateen, write_hstateen,
+                         .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_HSTATEEN3H] = { "hstateen3h", hstateen, read_hstateenh,
+                          write_hstateenh,
+                          .min_priv_ver = PRIV_VERSION_1_12_0 },
+
+    [CSR_SSTATEEN0] = { "sstateen0", sstateen, read_sstateen, write_sstateen,
+                         .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_SSTATEEN1] = { "sstateen1", sstateen, read_sstateen, write_sstateen,
+                         .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_SSTATEEN2] = { "sstateen2", sstateen, read_sstateen, write_sstateen,
+                         .min_priv_ver = PRIV_VERSION_1_12_0 },
+    [CSR_SSTATEEN3] = { "sstateen3", sstateen, read_sstateen, write_sstateen,
+                         .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 2a437b29a1..84a75dbb08 100644
--- a/target/riscv/machine.c
+++ b/target/riscv/machine.c
@@ -262,6 +262,26 @@ 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;
@@ -347,6 +367,7 @@ const VMStateDescription vmstate_riscv_cpu = {
         &vmstate_kvmtimer,
         &vmstate_envcfg,
         &vmstate_debug,
+        &vmstate_smstateen,
         NULL
     }
 };
-- 
2.25.1




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