Re: [Qemu-riscv] [PATCH-4.2 v1 2/6] target/riscv: Remove strict perm checking for CSR R/W

[Jonathan Behrens]

Unless I'm missing something, this is the only place that QEMU checks the privilege level for read and writes to CSRs. The exact computation used here won't work with the hypervisor extension, but we also can't just get rid of privilege checking entirely...

Jonathan

On Thu, Jul 25, 2019 at 2:56 PM Alistair Francis <address@hidden> wrote:

The privledge check based on the CSR address mask 0x300 doesn't work
when using Hypervisor extensions so remove the check

Signed-off-by: Alistair Francis <address@hidden>
---
 target/riscv/csr.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index e0d4586760..af3b762c8b 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -797,9 +797,8 @@ int riscv_csrrw(CPURISCVState *env, int csrno, target_ulong *ret_value,

     /* check privileges and return -1 if check fails */
 #if !defined(CONFIG_USER_ONLY)
-    int csr_priv = get_field(csrno, 0x300);
     int read_only = get_field(csrno, 0xC00) == 3;
-    if ((write_mask && read_only) || (env->priv < csr_priv)) {
+    if (write_mask && read_only) {
         return -1;
     }
 #endif
--
2.22.0