[Part1 PATCH v4 07/17] x86/efi: Access EFI data as encrypted when SEV is active

[Part1 PATCH v4 07/17] x86/efi: Access EFI data as encrypted when SEV is active

[Brijesh Singh]

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

EFI data is encrypted when the kernel is run under SEV. Update the
page table references to be sure the EFI memory areas are accessed
encrypted.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-efi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: x86@kernel.org
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 arch/x86/platform/efi/efi_64.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 12e83888e5b9..5469c9319f43 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -32,6 +32,7 @@
 #include <linux/reboot.h>
 #include <linux/slab.h>
 #include <linux/ucs2_string.h>
+#include <linux/mem_encrypt.h>
 
 #include <asm/setup.h>
 #include <asm/page.h>
@@ -369,7 +370,11 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
 	 * as trim_bios_range() will reserve the first page and isolate it away
 	 * from memory allocators anyway.
 	 */
-	if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, _PAGE_RW)) {
+	pf = _PAGE_RW;
+	if (sev_active())
+		pf |= _PAGE_ENC;
+
+	if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, pf)) {
 		pr_err("Failed to create 1:1 mapping for the first page!\n");
 		return 1;
 	}
@@ -412,6 +417,9 @@ static void __init __map_region(efi_memory_desc_t *md, u64 va)
 	if (!(md->attribute & EFI_MEMORY_WB))
 		flags |= _PAGE_PCD;
 
+	if (sev_active())
+		flags |= _PAGE_ENC;
+
 	pfn = md->phys_addr >> PAGE_SHIFT;
 	if (kernel_map_pages_in_pgd(pgd, pfn, va, md->num_pages, flags))
 		pr_warn("Error mapping PA 0x%llx -> VA 0x%llx!\n",
@@ -538,6 +546,9 @@ static int __init efi_update_mem_attr(struct mm_struct *mm, efi_memory_desc_t *m
 	if (!(md->attribute & EFI_MEMORY_RO))
 		pf |= _PAGE_RW;
 
+	if (sev_active())
+		pf |= _PAGE_ENC;
+
 	return efi_update_mappings(md, pf);
 }
 
@@ -589,6 +600,9 @@ void __init efi_runtime_update_mappings(void)
 			(md->type != EFI_RUNTIME_SERVICES_CODE))
 			pf |= _PAGE_RW;
 
+		if (sev_active())
+			pf |= _PAGE_ENC;
+
 		efi_update_mappings(md, pf);
 	}
 }
-- 
2.9.5

Re: [Part1 PATCH v4 07/17] x86/efi: Access EFI data as encrypted when SEV is active

[Borislav Petkov]

On Sat, Sep 16, 2017 at 07:34:08AM -0500, Brijesh Singh wrote:
> From: Tom Lendacky <thomas.lendacky@amd.com>
> 
> EFI data is encrypted when the kernel is run under SEV. Update the
> page table references to be sure the EFI memory areas are accessed
> encrypted.
> 
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Borislav Petkov <bp@suse.de>
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Matt Fleming <matt@codeblueprint.co.uk>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: linux-efi@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: x86@kernel.org
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
>  arch/x86/platform/efi/efi_64.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)

Reviewed-by: Borislav Petkov <bp@suse.de>

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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