Since migration of guests using SAO to ISA 3.1 hosts may cause issues,
disable PROT_SAO in LPARs by default and introduce a new Kconfig option
PPC_PROT_SAO_LPAR to allow users to enable it if desired.
Signed-off-by: Shawn Anastasio <sh...@anastas.io>
---
arch/powerpc/Kconfig | 12 ++++++++++++
arch/powerpc/include/asm/mman.h | 9 +++++++--
2 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 1f48bbfb3ce9..65bed1fdeaad 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -860,6 +860,18 @@ config PPC_SUBPAGE_PROT
If unsure, say N here.
+config PPC_PROT_SAO_LPAR
+ bool "Support PROT_SAO mappings in LPARs"
+ depends on PPC_BOOK3S_64
+ help
+ This option adds support for PROT_SAO mappings from userspace
+ inside LPARs on supported CPUs.
+
+ This may cause issues when performing guest migration from
+ a CPU that supports SAO to one that does not.
+
+ If unsure, say N here.
+
config PPC_COPRO_BASE
bool
diff --git a/arch/powerpc/include/asm/mman.h b/arch/powerpc/include/asm/mman.h
index 4ba303ea27f5..7cb6d18f5cd6 100644
--- a/arch/powerpc/include/asm/mman.h
+++ b/arch/powerpc/include/asm/mman.h
@@ -40,8 +40,13 @@ static inline bool arch_validate_prot(unsigned long prot,
unsigned long addr)
{
if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM | PROT_SAO))
return false;
- if ((prot & PROT_SAO) && !cpu_has_feature(CPU_FTR_SAO))
- return false;
+ if (prot & PROT_SAO) {
+ if (!cpu_has_feature(CPU_FTR_SAO))
+ return false;
+ if (firmware_has_feature(FW_FEATURE_LPAR) &&
+ !IS_ENABLED(CONFIG_PPC_PROT_SAO_LPAR))
+ return false;
+ }
return true;
}
#define arch_validate_prot arch_validate_prot
--
2.28.0
