x86/mm: Use proper encryption attributes with /dev/mem

When accessing memory using /dev/mem (or /dev/kmem) use the proper
encryption attributes when mapping the memory.

To insure the proper attributes are applied when reading or writing
/dev/mem, update the xlate_dev_mem_ptr() function to use memremap()
which will essentially perform the same steps of applying __va for
RAM or using ioremap() if not RAM.

To insure the proper attributes are applied when mmapping /dev/mem,
update the phys_mem_access_prot() to call phys_mem_access_encrypted(),
a new function which will check if the memory should be mapped encrypted
or not. If it is not to be mapped encrypted then the VMA protection
value is updated to remove the encryption bit.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
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: Matt Fleming <matt@codeblueprint.co.uk>
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/c917f403ab9f61cbfd455ad6425ed8429a5e7b54.1500319216.git.thomas.lendacky@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 88990ab87961..fe7d57a8fb60 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -744,6 +744,9 @@ EXPORT_SYMBOL(arch_io_free_memtype_wc);
 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 				unsigned long size, pgprot_t vma_prot)
 {
+	if (!phys_mem_access_encrypted(pfn << PAGE_SHIFT, size))
+		vma_prot = pgprot_decrypted(vma_prot);
+
 	return vma_prot;
 }