Re: [PATCH 1/4] target/riscv: Fix csr number based privilege checking

[Frank Chang]

Reviewed-by: Frank Chang <frank.chang@sifive.com>

On Fri, Apr 29, 2022 at 11:34 AM Anup Patel <apatel@ventanamicro.com> wrote:

When hypervisor and VS CSRs are accessed from VS-mode or VU-mode,
the riscv_csrrw_check() function should generate virtual instruction
trap instead illegal instruction trap.

Fixes: 533c91e8f22c ("target/riscv: Use RISCVException enum for
CSR access")
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
 target/riscv/csr.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 3500e07f92..2bf0a97196 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -3139,7 +3139,7 @@ static inline RISCVException riscv_csrrw_check(CPURISCVState *env,
     int read_only = get_field(csrno, 0xC00) == 3;
     int csr_min_priv = csr_ops[csrno].min_priv_ver;
 #if !defined(CONFIG_USER_ONLY)
-    int effective_priv = env->priv;
+    int csr_priv, effective_priv = env->priv;

     if (riscv_has_ext(env, RVH) &&
         env->priv == PRV_S &&
@@ -3152,7 +3152,11 @@ static inline RISCVException riscv_csrrw_check(CPURISCVState *env,
         effective_priv++;
     }

-    if (!env->debugger && (effective_priv < get_field(csrno, 0x300))) {
+    csr_priv = get_field(csrno, 0x300);
+    if (!env->debugger && (effective_priv < csr_priv)) {
+        if (csr_priv == (PRV_S + 1) && riscv_cpu_virt_enabled(env)) {
+            return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
+        }
         return RISCV_EXCP_ILLEGAL_INST;
     }
 #endif
--
2.34.1