[PATCH 1/2] target/riscv: Fix up masking of vsip/vsie accesses

[Andrew Bresticker]

The current logic attempts to shift the VS-level bits into their correct
position in mip while leaving the remaining bits in-tact. This is both
pointless and likely incorrect since one would expect that any new, future
VS-level interrupts will get their own position in mip rather than sharing
with their (H)S-level equivalent. Fix this, and make the logic more
readable, by just making off the VS-level bits and shifting them into
position.

This also fixes reads of vsip, which would only ever report vsip.VSSIP
since the non-writable bits got masked off as well.

Fixes: d028ac7512f1 ("arget/riscv: Implement AIA CSRs for 64 local interrupts 
on RV32")
Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com>
---
 target/riscv/csr.c | 35 +++++++++++------------------------
 1 file changed, 11 insertions(+), 24 deletions(-)

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 5c9a7ee287..984548bf87 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -1975,22 +1975,15 @@ static RISCVException rmw_vsie64(CPURISCVState *env, 
int csrno,
                                  uint64_t new_val, uint64_t wr_mask)
 {
     RISCVException ret;
-    uint64_t rval, vsbits, mask = env->hideleg & VS_MODE_INTERRUPTS;
+    uint64_t rval, mask = env->hideleg & VS_MODE_INTERRUPTS;
 
     /* Bring VS-level bits to correct position */
-    vsbits = new_val & (VS_MODE_INTERRUPTS >> 1);
-    new_val &= ~(VS_MODE_INTERRUPTS >> 1);
-    new_val |= vsbits << 1;
-    vsbits = wr_mask & (VS_MODE_INTERRUPTS >> 1);
-    wr_mask &= ~(VS_MODE_INTERRUPTS >> 1);
-    wr_mask |= vsbits << 1;
+    new_val = (new_val & (VS_MODE_INTERRUPTS >> 1)) << 1;
+    wr_mask = (wr_mask & (VS_MODE_INTERRUPTS >> 1)) << 1;
 
     ret = rmw_mie64(env, csrno, &rval, new_val, wr_mask & mask);
     if (ret_val) {
-        rval &= mask;
-        vsbits = rval & VS_MODE_INTERRUPTS;
-        rval &= ~VS_MODE_INTERRUPTS;
-        *ret_val = rval | (vsbits >> 1);
+        *ret_val = (rval & mask) >> 1;
     }
 
     return ret;
@@ -2191,22 +2184,16 @@ static RISCVException rmw_vsip64(CPURISCVState *env, 
int csrno,
                                  uint64_t new_val, uint64_t wr_mask)
 {
     RISCVException ret;
-    uint64_t rval, vsbits, mask = env->hideleg & vsip_writable_mask;
+    uint64_t rval, mask = env->hideleg & VS_MODE_INTERRUPTS;
 
     /* Bring VS-level bits to correct position */
-    vsbits = new_val & (VS_MODE_INTERRUPTS >> 1);
-    new_val &= ~(VS_MODE_INTERRUPTS >> 1);
-    new_val |= vsbits << 1;
-    vsbits = wr_mask & (VS_MODE_INTERRUPTS >> 1);
-    wr_mask &= ~(VS_MODE_INTERRUPTS >> 1);
-    wr_mask |= vsbits << 1;
-
-    ret = rmw_mip64(env, csrno, &rval, new_val, wr_mask & mask);
+    new_val = (new_val & (VS_MODE_INTERRUPTS >> 1)) << 1;
+    wr_mask = (wr_mask & (VS_MODE_INTERRUPTS >> 1)) << 1;
+
+    ret = rmw_mip64(env, csrno, &rval, new_val,
+                    wr_mask & mask & vsip_writable_mask);
     if (ret_val) {
-        rval &= mask;
-        vsbits = rval & VS_MODE_INTERRUPTS;
-        rval &= ~VS_MODE_INTERRUPTS;
-        *ret_val = rval | (vsbits >> 1);
+        *ret_val = (rval & mask) >> 1;
     }
 
     return ret;
-- 
2.25.1