arm64: KVM: Enable Common Not Private translations

We rely on cpufeature framework to detect and enable CNP so for KVM we
need to patch hyp to set CNP bit just before TTBR0_EL2 gets written.

For the guest we encode CNP bit while building vttbr, so we don't need
to bother with that in a world switch.

Reviewed-by: James Morse <james.morse@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm/include/asm/kvm_arm.h

@@ -161,6 +161,7 @@
 #else
 #define VTTBR_X		(5 - KVM_T0SZ)
 #endif
+#define VTTBR_CNP_BIT     _AC(1, UL)
 #define VTTBR_BADDR_MASK  (((_AC(1, ULL) << (40 - VTTBR_X)) - 1) << VTTBR_X)
 #define VTTBR_VMID_SHIFT  _AC(48, ULL)
 #define VTTBR_VMID_MASK(size)	(_AT(u64, (1 << size) - 1) << VTTBR_VMID_SHIFT)

arch/arm/include/asm/kvm_mmu.h

@@ -355,6 +355,11 @@ static inline int hyp_map_aux_data(void)
 
 #define kvm_phys_to_vttbr(addr)		(addr)
 
+static inline bool kvm_cpu_has_cnp(void)
+{
+	return false;
+}
+
 #endif	/* !__ASSEMBLY__ */
 
 #endif /* __ARM_KVM_MMU_H__ */