arm64: mm: Remove MAX_USER_VA_BITS definition

commit 9b31cf49 ("arm64: mm: Introduce MAX_USER_VA_BITS definition")
introduced the MAX_USER_VA_BITS definition, which was used to support
the arm64 mm use-cases where the user-space could use 52-bit virtual
addresses whereas the kernel-space would still could a maximum of 48-bit
virtual addressing.

But, now with commit b6d00d47 ("arm64: mm: Introduce 52-bit Kernel
VAs"), we removed the 52-bit user/48-bit kernel kconfig option and hence
there is no longer any scenario where user VA != kernel VA size
(even with CONFIG_ARM64_FORCE_52BIT enabled, the same is true).

Hence we can do away with the MAX_USER_VA_BITS macro as it is equal to
VA_BITS (maximum VA space size) in all possible use-cases. Note that
even though the 'vabits_actual' value would be 48 for arm64 hardware
which don't support LVA-8.2 extension (even when CONFIG_ARM64_VA_BITS_52
is enabled), VA_BITS would still be set to a value 52. Hence this change
would be safe in all possible VA address space combinations.

Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-kernel@vger.kernel.org
Cc: kexec@lists.infradead.org
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Bhupesh Sharma <bhsharma@redhat.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/memory.h

@@ -69,12 +69,6 @@
 #define KERNEL_START		_text
 #define KERNEL_END		_end
 
-#ifdef CONFIG_ARM64_VA_BITS_52
-#define MAX_USER_VA_BITS	52
-#else
-#define MAX_USER_VA_BITS	VA_BITS
-#endif
-
 /*
  * Generic and tag-based KASAN require 1/8th and 1/16th of the kernel virtual
  * address space for the shadow region respectively. They can bloat the stack

arch/arm64/include/asm/pgtable-hwdef.h

@@ -69,7 +69,7 @@
 #define PGDIR_SHIFT		ARM64_HW_PGTABLE_LEVEL_SHIFT(4 - CONFIG_PGTABLE_LEVELS)
 #define PGDIR_SIZE		(_AC(1, UL) << PGDIR_SHIFT)
 #define PGDIR_MASK		(~(PGDIR_SIZE-1))
-#define PTRS_PER_PGD		(1 << (MAX_USER_VA_BITS - PGDIR_SHIFT))
+#define PTRS_PER_PGD		(1 << (VA_BITS - PGDIR_SHIFT))
 
 /*
  * Section address mask and size definitions.

arch/arm64/include/asm/processor.h

@@ -9,7 +9,7 @@
 #define __ASM_PROCESSOR_H
 
 #define KERNEL_DS		UL(-1)
-#define USER_DS			((UL(1) << MAX_USER_VA_BITS) - 1)
+#define USER_DS			((UL(1) << VA_BITS) - 1)
 
 /*
  * On arm64 systems, unaligned accesses by the CPU are cheap, and so there is