|
| From: | Alvin Chang |
| Subject: | RE: [PATCH v5] target/riscv: update checks on writing pmpcfg for Smepmp to version 1.0 |
| Date: | Wed, 6 Dec 2023 09:12:12 +0800 |
Ping for review.
> -----Original Message-----
> From: Alvin Che-Chia Chang(張哲嘉) <alvinga@andestech.com>
> Sent: Tuesday, November 14, 2023 10:23 AM
> To: qemu-riscv@nongnu.org; qemu-devel@nongnu.org
> Cc: alistair.francis@wdc.com; liweiwei@iscas.ac.cn; Alvin Che-Chia Chang(張
> 哲嘉) <alvinga@andestech.com>
> Subject: [PATCH v5] target/riscv: update checks on writing pmpcfg for Smepmp
> to version 1.0
>
> Current checks on writing pmpcfg for Smepmp follows Smepmp version 0.9.1.
> However, Smepmp specification has already been ratified, and there are some
> differences between version 0.9.1 and 1.0. In this commit we update the
> checks of writing pmpcfg to follow Smepmp version 1.0.
>
> When mseccfg.MML is set, the constraints to modify PMP rules are:
> 1. Locked rules cannot be removed or modified until a PMP reset, unless
> mseccfg.RLB is set.
> 2. From Smepmp specification version 1.0, chapter 2 section 4b:
> Adding a rule with executable privileges that either is M-mode-only
> or a locked Shared-Region is not possible and such pmpcfg writes are
> ignored, leaving pmpcfg unchanged.
>
> The commit transfers the value of pmpcfg into the index of the Smepmp truth
> table, and checks the rules by aforementioned specification changes.
>
> Signed-off-by: Alvin Chang <alvinga@andestech.com>
> ---
> Changes from v4: Rebase on master.
>
> Changes from v3: Modify "epmp_operation" to "smepmp_operation".
>
> Changes from v2: Adopt switch case ranges and numerical order.
>
> Changes from v1: Convert ePMP over to Smepmp.
>
> target/riscv/pmp.c | 40 ++++++++++++++++++++++++++++++++--------
> 1 file changed, 32 insertions(+), 8 deletions(-)
>
> diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c index
> 162e88a90a..4069514069 100644
> --- a/target/riscv/pmp.c
> +++ b/target/riscv/pmp.c
> @@ -102,16 +102,40 @@ static bool pmp_write_cfg(CPURISCVState *env,
> uint32_t pmp_index, uint8_t val)
> locked = false;
> }
>
> - /* mseccfg.MML is set */
> - if (MSECCFG_MML_ISSET(env)) {
> - /* not adding execute bit */
> - if ((val & PMP_LOCK) != 0 && (val & PMP_EXEC) !=
> PMP_EXEC) {
> + /*
> + * mseccfg.MML is set. Locked rules cannot be removed or
> modified
> + * until a PMP reset. Besides, from Smepmp specification
> version 1.0
> + * , chapter 2 section 4b says:
> + * Adding a rule with executable privileges that either is
> + * M-mode-only or a locked Shared-Region is not possible and
> such
> + * pmpcfg writes are ignored, leaving pmpcfg unchanged.
> + */
> + if (MSECCFG_MML_ISSET(env) && !pmp_is_locked(env,
> pmp_index)) {
> + /*
> + * Convert the PMP permissions to match the truth table
> in the
> + * Smepmp spec.
> + */
> + const uint8_t smepmp_operation =
> + ((val & PMP_LOCK) >> 4) | ((val & PMP_READ) << 2)
> |
> + (val & PMP_WRITE) | ((val & PMP_EXEC) >> 2);
> +
> + switch (smepmp_operation) {
> + case 0 ... 8:
> locked = false;
> - }
> - /* shared region and not adding X bit */
> - if ((val & PMP_LOCK) != PMP_LOCK &&
> - (val & 0x7) != (PMP_WRITE | PMP_EXEC)) {
> + break;
> + case 9 ... 11:
> + break;
> + case 12:
> + locked = false;
> + break;
> + case 13:
> + break;
> + case 14:
> + case 15:
> locked = false;
> + break;
> + default:
> + g_assert_not_reached();
> }
> }
> } else {
> --
> 2.34.1
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