Commit 9b725a90 authored by Shawn Anastasio's avatar Shawn Anastasio Committed by Michael Ellerman
Browse files

powerpc/64s: Disallow PROT_SAO in LPARs by default 



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: default avatarShawn Anastasio <shawn@anastas.io>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200821185558.35561-3-shawn@anastas.io
parent 12564485

arch/powerpc/Kconfig

+12 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/include/asm/mman.h

+7 −2
Original line number Diff line number Diff line
@@ -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))

	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

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