[RFC PATCH v2 13/20] x86: Decrypt trampoline area if memory encryption is active
From: Tom Lendacky <thomas.lendacky@amd.com>
Date: 2016-08-22 23:13:50
Also in:
kvm, linux-arch, linux-iommu, linux-mm, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
When Secure Memory Encryption is enabled, the trampoline area must not be encrypted. A cpu running in real mode will not be able to decrypt memory that has been encrypted because it will not be able to use addresses with the memory encryption mask. Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> --- arch/x86/realmode/init.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index 5db706f1..f74925f 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c@@ -6,6 +6,7 @@ #include <asm/pgtable.h> #include <asm/realmode.h> #include <asm/tlbflush.h> +#include <asm/mem_encrypt.h> struct real_mode_header *real_mode_header; u32 *trampoline_cr4_features;
@@ -130,6 +131,14 @@ static void __init set_real_mode_permissions(void) unsigned long text_start = (unsigned long) __va(real_mode_header->text_start); + /* + * If memory encryption is active, the trampoline area will need to + * be in non-encrypted memory in order to bring up other processors + * successfully. + */ + sme_early_mem_dec(__pa(base), size); + sme_set_mem_dec(base, size); + set_memory_nx((unsigned long) base, size >> PAGE_SHIFT); set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT); set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT); --
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