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lib: sbi_domain: allow specifying inaccessible region

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According to the RISC‑V Privileged Specification, SmePMP
regions that grant no access in any privilege mode are
valid. Allow such regions to be specified.

Signed-off-by: Yu-Chien Peter Lin <peter.lin@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20251008084444.3525615-3-peter.lin@sifive.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Yu-Chien Peter Lin
2025-10-08 16:44:38 +08:00
committed by Anup Patel
parent 32c1d38dcf
commit 667eed2266
2 changed files with 11 additions and 5 deletions
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12
lib/sbi/sbi_domain.c
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@@ -126,7 +126,17 @@ unsigned int sbi_domain_get_smepmp_flags(struct sbi_domain_memregion *reg)
{
unsigned int pmp_flags = 0;
if (SBI_DOMAIN_MEMREGION_IS_SHARED(reg->flags)) {
if ((reg->flags & SBI_DOMAIN_MEMREGION_ACCESS_MASK) == 0) {
/*
* Region is inaccessible in all privilege modes.
*
* SmePMP allows two encodings for an inaccessible region:
* - pmpcfg.LRWX = 0000 (Inaccessible region)
* - pmpcfg.LRWX = 1000 (Locked inaccessible region)
* We use the first encoding here.
*/
return 0;
} else if (SBI_DOMAIN_MEMREGION_IS_SHARED(reg->flags)) {
/* Read only for both M and SU modes */
if (SBI_DOMAIN_MEMREGION_IS_SUR_MR(reg->flags))
pmp_flags = (PMP_L | PMP_R | PMP_W | PMP_X);