[PATCH RFC v10 16/22] arm64: kpkeys: Support KPKEYS_CTX_PGTABLES

[Kevin Brodsky <kevin.brodsky@arm.com>]

Enable RW access to KPKEYS_PKEY_PGTABLES (used to map page table
pages) if switching to KPKEYS_CTX_PGTABLES, otherwise only grant RO
access.

Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
---
 arch/arm64/include/asm/kpkeys.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kpkeys.h b/arch/arm64/include/asm/kpkeys.h
index 70d85b0d69d6..6f6022b6cdcc 100644
--- a/arch/arm64/include/asm/kpkeys.h
+++ b/arch/arm64/include/asm/kpkeys.h
@@ -12,7 +12,8 @@
  * Equivalent to por_set_kpkeys_context(0, KPKEYS_CTX_DEFAULT), but can also be
  * used in assembly.
  */
-#define POR_EL1_INIT	POR_ELx_PERM_PREP(0, POE_RWX)
+#define POR_EL1_INIT	(POR_ELx_PERM_PREP(0, POE_RWX) | \
+			 POR_ELx_PERM_PREP(KPKEYS_PKEY_PGTABLES, POE_R))
 
 #ifndef __ASSEMBLY__
 
@@ -33,6 +34,8 @@ static inline bool arch_supports_kpkeys_early(void)
 static inline u64 por_set_kpkeys_context(u64 por, enum kpkeys_ctx ctx)
 {
 	por = por_elx_set_pkey_perms(por, 0, POE_RWX);
+	por = por_elx_set_pkey_perms(por, KPKEYS_PKEY_PGTABLES,
+				     ctx == KPKEYS_CTX_PGTABLES ? POE_RW : POE_R);
 
 	return por;
 }

-- 
2.56.0