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x86/mm: Add support to access boot related data in the clear

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Boot data (such as EFI related data) is not encrypted when the system is
booted because UEFI/BIOS does not run with SME active. In order to access
this data properly it needs to be mapped decrypted.

Update early_memremap() to provide an arch specific routine to modify the
pagetable protection attributes before they are applied to the new
mapping. This is used to remove the encryption mask for boot related data.

Update memremap() to provide an arch specific routine to determine if RAM
remapping is allowed.  RAM remapping will cause an encrypted mapping to be
generated. By preventing RAM remapping, ioremap_cache() will be used
instead, which will provide a decrypted mapping of the boot related data.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Toshimitsu Kani <toshi.kani@hpe.com>
Cc: kasan-dev@googlegroups.com
Cc: kvm@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-efi@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/81fb6b4117a5df6b9f2eda342f81bbef4b23d2e5.1500319216.git.thomas.lendacky@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Tom Lendacky
2017-07-17 16:10:16 -05:00
committed by Ingo Molnar
parent 38eecccdf4
commit 8f716c9b5f
5 changed files with 218 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
mm/early_ioremap.c
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@@ -30,6 +30,13 @@ early_param("early_ioremap_debug", early_ioremap_debug_setup);
static int after_paging_init __initdata;
pgprot_t __init __weak early_memremap_pgprot_adjust(resource_size_t phys_addr,
unsigned long size,
pgprot_t prot)
{
return prot;
}
void __init __weak early_ioremap_shutdown(void)
{
}
@@ -215,14 +222,19 @@ early_ioremap(resource_size_t phys_addr, unsigned long size)
void __init *
early_memremap(resource_size_t phys_addr, unsigned long size)
{
return (__force void *)__early_ioremap(phys_addr, size,
FIXMAP_PAGE_NORMAL);
pgprot_t prot = early_memremap_pgprot_adjust(phys_addr, size,
FIXMAP_PAGE_NORMAL);
return (__force void *)__early_ioremap(phys_addr, size, prot);
}
#ifdef FIXMAP_PAGE_RO
void __init *
early_memremap_ro(resource_size_t phys_addr, unsigned long size)
{
return (__force void *)__early_ioremap(phys_addr, size, FIXMAP_PAGE_RO);
pgprot_t prot = early_memremap_pgprot_adjust(phys_addr, size,
FIXMAP_PAGE_RO);
return (__force void *)__early_ioremap(phys_addr, size, prot);
}
#endif