x86: Make ARCH_USE_MEMREMAP_PROT a generic Kconfig symbol

commit ce9084ba0d1d8030adee7038ace32f8d9d423d0f upstream.

Turn ARCH_USE_MEMREMAP_PROT into a generic Kconfig symbol, and fix the
dependency expression to reflect that AMD_MEM_ENCRYPT depends on it,
instead of the other way around. This will permit ARCH_USE_MEMREMAP_PROT
to be selected by other architectures.

Note that the encryption related early memremap routines in
arch/x86/mm/ioremap.c cannot be built for 32-bit x86 without triggering
the following warning:

     arch/x86//mm/ioremap.c: In function 'early_memremap_encrypted':
  >> arch/x86/include/asm/pgtable_types.h:193:27: warning: conversion from
                     'long long unsigned int' to 'long unsigned int' changes
                     value from '9223372036854776163' to '355' [-Woverflow]
      #define __PAGE_KERNEL_ENC (__PAGE_KERNEL | _PAGE_ENC)
                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~
     arch/x86//mm/ioremap.c:713:46: note: in expansion of macro '__PAGE_KERNEL_ENC'
       return early_memremap_prot(phys_addr, size, __PAGE_KERNEL_ENC);

which essentially means they are 64-bit only anyway. However, we cannot
make them dependent on CONFIG_ARCH_HAS_MEM_ENCRYPT, since that is always
defined, even for i386 (and changing that results in a slew of build errors)

So instead, build those routines only if CONFIG_AMD_MEM_ENCRYPT is
defined.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Jeffrey Hugo <jhugo@codeaurora.org>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Jones <pjones@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20190202094119.13230-9-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 6 insertions, 6 deletions

diff --git a/arch/Kconfig b/arch/Kconfig
index 95567f683275..c2e73c01d7ad 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -980,4 +980,7 @@ config HAVE_ARCH_COMPILER_H
 	  linux/compiler-*.h in order to override macro definitions that those
 	  headers generally provide.
 
+config ARCH_USE_MEMREMAP_PROT
+	bool
+
 source "kernel/gcov/Kconfig"
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 290254849f97..dc1a94c1ac3e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1449,6 +1449,7 @@ config ARCH_HAS_MEM_ENCRYPT
 config AMD_MEM_ENCRYPT
 	bool "AMD Secure Memory Encryption (SME) support"
 	depends on X86_64 && CPU_SUP_AMD
+	select ARCH_USE_MEMREMAP_PROT
 	---help---
 	  Say yes to enable support for the encryption of system memory.
 	  This requires an AMD processor that supports Secure Memory
@@ -1467,10 +1468,6 @@ config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
 	  If set to N, then the encryption of system memory can be
 	  activated with the mem_encrypt=on command line option.
 
-config ARCH_USE_MEMREMAP_PROT
-	def_bool y
-	depends on AMD_MEM_ENCRYPT
-
 # Common NUMA Features
 config NUMA
 	bool "Numa Memory Allocation and Scheduler Support"
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 7bebdd0273d3..3faf9667cc40 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -626,7 +626,7 @@ bool phys_mem_access_encrypted(unsigned long phys_addr, unsigned long size)
 	return arch_memremap_can_ram_remap(phys_addr, size, 0);
 }
 
-#ifdef CONFIG_ARCH_USE_MEMREMAP_PROT
+#ifdef CONFIG_AMD_MEM_ENCRYPT
 /* Remap memory with encryption */
 void __init *early_memremap_encrypted(resource_size_t phys_addr,
 				      unsigned long size)
@@ -668,7 +668,7 @@ void __init *early_memremap_decrypted_wp(resource_size_t phys_addr,
 
 	return early_memremap_prot(phys_addr, size, __PAGE_KERNEL_NOENC_WP);
 }
-#endif	/* CONFIG_ARCH_USE_MEMREMAP_PROT */
+#endif	/* CONFIG_AMD_MEM_ENCRYPT */
 
 static pte_t bm_pte[PAGE_SIZE/sizeof(pte_t)] __page_aligned_bss;