linux-kernel - [PATCH 1/8] x86/ioremap: Selectively build arch override encryption functions

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Date:   Tue, 28 Sep 2021 21:10:02 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Andi Kleen <ak@...ux.intel.com>, Andy Lutomirski <luto@...nel.org>,
        Ard Biesheuvel <ardb@...nel.org>, Baoquan He <bhe@...hat.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Dave Young <dyoung@...hat.com>,
        David Airlie <airlied@...ux.ie>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Joerg Roedel <joro@...tes.org>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        VMware Graphics <linux-graphics-maintainer@...are.com>,
        Will Deacon <will@...nel.org>,
        Christoph Hellwig <hch@...radead.org>, x86@...nel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
        iommu@...ts.linux-foundation.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        kexec@...ts.infradead.org
Subject: [PATCH 1/8] x86/ioremap: Selectively build arch override encryption functions

From: Tom Lendacky <thomas.lendacky@....com>

In preparation for other uses of the cc_platform_has() function
besides AMD's memory encryption support, selectively build the
AMD memory encryption architecture override functions only when
CONFIG_AMD_MEM_ENCRYPT=y. These functions are:

- early_memremap_pgprot_adjust()
- arch_memremap_can_ram_remap()

Additionally, routines that are only invoked by these architecture
override functions can also be conditionally built. These functions are:

- memremap_should_map_decrypted()
- memremap_is_efi_data()
- memremap_is_setup_data()
- early_memremap_is_setup_data()

And finally, phys_mem_access_encrypted() is conditionally built as well,
but requires a static inline version of it when CONFIG_AMD_MEM_ENCRYPT is
not set.

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/include/asm/io.h | 8 ++++++++
 arch/x86/mm/ioremap.c     | 2 +-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 841a5d104afa..5c6a4af0b911 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -391,6 +391,7 @@ extern void arch_io_free_memtype_wc(resource_size_t start, resource_size_t size)
 #define arch_io_reserve_memtype_wc arch_io_reserve_memtype_wc
 #endif
 
+#ifdef CONFIG_AMD_MEM_ENCRYPT
 extern bool arch_memremap_can_ram_remap(resource_size_t offset,
 					unsigned long size,
 					unsigned long flags);
@@ -398,6 +399,13 @@ extern bool arch_memremap_can_ram_remap(resource_size_t offset,
 
 extern bool phys_mem_access_encrypted(unsigned long phys_addr,
 				      unsigned long size);
+#else
+static inline bool phys_mem_access_encrypted(unsigned long phys_addr,
+					     unsigned long size)
+{
+	return true;
+}
+#endif
 
 /**
  * iosubmit_cmds512 - copy data to single MMIO location, in 512-bit units
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 60ade7dd71bd..ccff76cedd8f 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -508,6 +508,7 @@ void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
 	memunmap((void *)((unsigned long)addr & PAGE_MASK));
 }
 
+#ifdef CONFIG_AMD_MEM_ENCRYPT
 /*
  * Examine the physical address to determine if it is an area of memory
  * that should be mapped decrypted.  If the memory is not part of the
@@ -746,7 +747,6 @@ bool phys_mem_access_encrypted(unsigned long phys_addr, unsigned long size)
 	return arch_memremap_can_ram_remap(phys_addr, size, 0);
 }
 
-#ifdef CONFIG_AMD_MEM_ENCRYPT
 /* Remap memory with encryption */
 void __init *early_memremap_encrypted(resource_size_t phys_addr,
 				      unsigned long size)
-- 
2.29.2