Re: [PATCH v3] target/riscv: update checks on writing pmpcfg for Smepmp

[Himanshu Chauhan]

> On 19-Sep-2023, at 10:51 AM, Alistair Francis <alistair23@gmail.com> wrote:
> 
> On Tue, Sep 19, 2023 at 3:08 PM Chang Alvin <vivahavey@gmail.com> wrote:
>> 
>>> -----Original Message-----
>> 
>>> From: Alistair Francis <alistair23@gmail.com>
>> 
>>> Sent: Tuesday, September 19, 2023 12:42 PM
>> 
>>> To: Alvin Che-Chia Chang(張哲嘉) <alvinga@andestech.com>
>> 
>>> Cc: qemu-riscv@nongnu.org; qemu-devel@nongnu.org;
>> 
>>> alistair.francis@wdc.com; ajones@ventanamicro.com
>> 
>>> Subject: Re: [PATCH v3] target/riscv: update checks on writing pmpcfg for
>> 
>>> Smepmp to version 1.0
>> 
>>> 
>> 
>>> On Fri, Sep 15, 2023 at 6:32 PM Alvin Chang <alvinga@andestech.com> wrote:
>> 
>>>> 
>> 
>>>> 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 v2: Adopt switch case ranges and numerical order.
>> 
>>>> 
>> 
>>>> Changes from v1: Convert ePMP over to Smepmp.
>> 
>>> 
>> 
>>> Did this part get lost?
>> 
>>> 
>> 
>>> Alistair
>> 
>>> 
>> 
>> 
>> Sorry, do you mean that the term "ePMP" should be changed to "Smepmp" in 
>> source code?
> 
> We still call it epmp to users and it's still marked as experimental.
> 
> See this line in the QEMU source:
> 
> MULTI_EXT_CFG_BOOL("x-epmp", epmp, false),
> 
> Alistair

I had sent a patch to rename epmp to Smepmp
https://www.mail-archive.com/qemu-devel@nongnu.org/msg967676.html


Regards
Himanshu