Do the following PMA changes of implicit PTE access need xFENCE to synchronize?

[terranfund]

First, I want to ensure PMA of PTE access is permitted to cache them the address translation cache.
If the above answer is true, I want to ask the following scenarios whether xFENCE is required to synchronize PMA setting and virtual memory system.

1. The location of PTE is changed
2. The cache-ability of PTE is changed
3. The memory attribute of PTE is changed from memory region to IO/vacant region, or vice-versa.

[gfavor]

On Fri, May 10, 2024 at 2:26 AM terranfund ***@***.***> wrote: First of all, I want to ensure PMA of PTE access is permitted to cache them the address translation cache. If the above answer is true, I want to ask the following scenarios whether xFENCE is required to synchronize PMA setting and virtual memory system. 1. The location of PTE is changed 2. The cache-ability of PTE is changed 3. The memory attributes of PTE is changed from memory region to IO/vacant region, or vice-versa. Since PMA details are very implementation-specific (and not specified by

the architecture), and PMAs are managed by M-mode firmware, it is up to that implementation-specific firmware to do any necessary sfence'ing when PMAs are changed. This is true for all memory accesses, not just PTE memory accesses.

[allenjbaum]

Configurable PMAs are custom and implementation defined, not defined by the spec, so I suspect there is a "correct" answer.

…

On Fri, May 10, 2024 at 2:26 AM terranfund ***@***.***> wrote: First of all, I want to ensure PMA of PTE access is permitted to cache them the address translation cache. If the above answer is true, I want to ask the following scenarios whether xFENCE is required to synchronize PMA setting and virtual memory system. 1. The location of PTE is changed 2. The cache-ability of PTE is changed 3. The memory attributes of PTE is changed from memory region to IO/vacant region, or vice-versa. — Reply to this email directly, view it on GitHub <#1392>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AHPXVJRQZGOFX4CYNDIURB3ZBSHE7AVCNFSM6AAAAABHQJR6VWVHI2DSMVQWIX3LMV43ASLTON2WKOZSGI4DSMZVG42DAOA> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[terranfund]

OK, got it. Thanks a lot.