[v2] target/riscv: pmp: Ignore writes when RW=01

[PATCH v2] target/riscv: pmp: Ignore writes when RW=01

Posted by Mayuresh Chitale 7 months, 1 week ago

As per the Priv spec: "The R, W, and X fields form a collective WARL
field for which the combinations with R=0 and W=1 are reserved."
However currently such writes are not ignored as ought to be. The
combinations with RW=01 are allowed only when the Smepmp extension
is enabled and mseccfg.MML is set.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
---
 target/riscv/pmp.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
index 5b14eb511a..8e25f145e0 100644
--- a/target/riscv/pmp.c
+++ b/target/riscv/pmp.c
@@ -120,6 +120,11 @@ static void pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val)
         if (locked) {
             qemu_log_mask(LOG_GUEST_ERROR, "ignoring pmpcfg write - locked\n");
         } else {
+            /* If !mseccfg.MML then ignore writes with encoding RW=01 */
+            if ((val & PMP_WRITE) && !(val & PMP_READ) &&
+                !MSECCFG_MML_ISSET(env)) {
+                val &= ~(PMP_WRITE | PMP_READ);
+            }
             env->pmp_state.pmp[pmp_index].cfg_reg = val;
             pmp_update_rule(env, pmp_index);
         }
-- 
2.34.1

Re: [PATCH v2] target/riscv: pmp: Ignore writes when RW=01

Posted by Alistair Francis 7 months ago

On Mon, Sep 25, 2023 at 9:11 PM Mayuresh Chitale
<mchitale@ventanamicro.com> wrote:
>
> As per the Priv spec: "The R, W, and X fields form a collective WARL
> field for which the combinations with R=0 and W=1 are reserved."
> However currently such writes are not ignored as ought to be. The
> combinations with RW=01 are allowed only when the Smepmp extension
> is enabled and mseccfg.MML is set.
>
> Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>

Do you mind rebasing this on
https://github.com/alistair23/qemu/tree/riscv-to-apply.next

Alistair

> ---
>  target/riscv/pmp.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
> index 5b14eb511a..8e25f145e0 100644
> --- a/target/riscv/pmp.c
> +++ b/target/riscv/pmp.c
> @@ -120,6 +120,11 @@ static void pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val)
>          if (locked) {
>              qemu_log_mask(LOG_GUEST_ERROR, "ignoring pmpcfg write - locked\n");
>          } else {
> +            /* If !mseccfg.MML then ignore writes with encoding RW=01 */
> +            if ((val & PMP_WRITE) && !(val & PMP_READ) &&
> +                !MSECCFG_MML_ISSET(env)) {
> +                val &= ~(PMP_WRITE | PMP_READ);
> +            }
>              env->pmp_state.pmp[pmp_index].cfg_reg = val;
>              pmp_update_rule(env, pmp_index);
>          }
> --
> 2.34.1
>
>

Re: [PATCH v2] target/riscv: pmp: Ignore writes when RW=01

Posted by Mayuresh Chitale 6 months, 3 weeks ago

On Mon, Oct 9, 2023 at 6:56 AM Alistair Francis <alistair23@gmail.com> wrote:
>
> On Mon, Sep 25, 2023 at 9:11 PM Mayuresh Chitale
> <mchitale@ventanamicro.com> wrote:
> >
> > As per the Priv spec: "The R, W, and X fields form a collective WARL
> > field for which the combinations with R=0 and W=1 are reserved."
> > However currently such writes are not ignored as ought to be. The
> > combinations with RW=01 are allowed only when the Smepmp extension
> > is enabled and mseccfg.MML is set.
> >
> > Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
>
> Do you mind rebasing this on
> https://github.com/alistair23/qemu/tree/riscv-to-apply.next
Ok, will do that.
>
> Alistair
>
> > ---
> >  target/riscv/pmp.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
> > index 5b14eb511a..8e25f145e0 100644
> > --- a/target/riscv/pmp.c
> > +++ b/target/riscv/pmp.c
> > @@ -120,6 +120,11 @@ static void pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val)
> >          if (locked) {
> >              qemu_log_mask(LOG_GUEST_ERROR, "ignoring pmpcfg write - locked\n");
> >          } else {
> > +            /* If !mseccfg.MML then ignore writes with encoding RW=01 */
> > +            if ((val & PMP_WRITE) && !(val & PMP_READ) &&
> > +                !MSECCFG_MML_ISSET(env)) {
> > +                val &= ~(PMP_WRITE | PMP_READ);
> > +            }
> >              env->pmp_state.pmp[pmp_index].cfg_reg = val;
> >              pmp_update_rule(env, pmp_index);
> >          }
> > --
> > 2.34.1
> >
> >

Re: [PATCH v2] target/riscv: pmp: Ignore writes when RW=01

Posted by Alistair Francis 7 months ago

On Mon, Sep 25, 2023 at 9:11 PM Mayuresh Chitale
<mchitale@ventanamicro.com> wrote:
>
> As per the Priv spec: "The R, W, and X fields form a collective WARL
> field for which the combinations with R=0 and W=1 are reserved."
> However currently such writes are not ignored as ought to be. The
> combinations with RW=01 are allowed only when the Smepmp extension
> is enabled and mseccfg.MML is set.
>
> Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>

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

Alistair

> ---
>  target/riscv/pmp.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
> index 5b14eb511a..8e25f145e0 100644
> --- a/target/riscv/pmp.c
> +++ b/target/riscv/pmp.c
> @@ -120,6 +120,11 @@ static void pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val)
>          if (locked) {
>              qemu_log_mask(LOG_GUEST_ERROR, "ignoring pmpcfg write - locked\n");
>          } else {
> +            /* If !mseccfg.MML then ignore writes with encoding RW=01 */
> +            if ((val & PMP_WRITE) && !(val & PMP_READ) &&
> +                !MSECCFG_MML_ISSET(env)) {
> +                val &= ~(PMP_WRITE | PMP_READ);
> +            }
>              env->pmp_state.pmp[pmp_index].cfg_reg = val;
>              pmp_update_rule(env, pmp_index);
>          }
> --
> 2.34.1
>
>