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powerpc/64s: Disallow PROT_SAO in LPARs by default

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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 <shawn@anastas.io>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200821185558.35561-3-shawn@anastas.io
This commit is contained in:
Shawn Anastasio 2020-08-21 13:55:57 -05:00 committed by Michael Ellerman
parent 12564485ed
commit 9b725a90a8
2 changed files with 19 additions and 2 deletions
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12
arch/powerpc/Kconfig
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@ -860,6 +860,18 @@ config PPC_SUBPAGE_PROT
If unsure, say N here. 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 config PPC_COPRO_BASE
bool bool

9
arch/powerpc/include/asm/mman.h
View File

@ -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)) if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM | PROT_SAO))
return false; return false;
if ((prot & PROT_SAO) && !cpu_has_feature(CPU_FTR_SAO)) if (prot & PROT_SAO) {
return false; 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; return true;
} }
#define arch_validate_prot arch_validate_prot #define arch_validate_prot arch_validate_prot