linux-kernel - [RFC PATCH v2 07/32] x86/efi: Access EFI data as encrypted when SEV is active

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Date:   Thu, 2 Mar 2017 10:13:21 -0500
From:   Brijesh Singh <brijesh.singh@....com>
To:     <simon.guinot@...uanux.org>, <linux-efi@...r.kernel.org>,
        <brijesh.singh@....com>, <kvm@...r.kernel.org>,
        <rkrcmar@...hat.com>, <matt@...eblueprint.co.uk>,
        <linux-pci@...r.kernel.org>, <linus.walleij@...aro.org>,
        <gary.hook@....com>, <linux-mm@...ck.org>,
        <paul.gortmaker@...driver.com>, <hpa@...or.com>, <cl@...ux.com>,
        <dan.j.williams@...el.com>, <aarcange@...hat.com>,
        <sfr@...b.auug.org.au>, <andriy.shevchenko@...ux.intel.com>,
        <herbert@...dor.apana.org.au>, <bhe@...hat.com>,
        <xemul@...allels.com>, <joro@...tes.org>, <x86@...nel.org>,
        <peterz@...radead.org>, <piotr.luc@...el.com>, <mingo@...hat.com>,
        <msalter@...hat.com>, <ross.zwisler@...ux.intel.com>, <bp@...e.de>,
        <dyoung@...hat.com>, <thomas.lendacky@....com>, <jroedel@...e.de>,
        <keescook@...omium.org>, <arnd@...db.de>, <toshi.kani@....com>,
        <mathieu.desnoyers@...icios.com>, <luto@...nel.org>,
        <devel@...uxdriverproject.org>, <bhelgaas@...gle.com>,
        <tglx@...utronix.de>, <mchehab@...nel.org>,
        <iamjoonsoo.kim@....com>, <labbott@...oraproject.org>,
        <tony.luck@...el.com>, <alexandre.bounine@....com>,
        <kuleshovmail@...il.com>, <linux-kernel@...r.kernel.org>,
        <mcgrof@...nel.org>, <mst@...hat.com>,
        <linux-crypto@...r.kernel.org>, <tj@...nel.org>,
        <pbonzini@...hat.com>, <akpm@...ux-foundation.org>,
        <davem@...emloft.net>
Subject: [RFC PATCH v2 07/32] x86/efi: Access EFI data as encrypted when SEV
 is active

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

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: Brijesh Singh <brijesh.singh@....com>
---
 arch/x86/platform/efi/efi_64.c |   15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 2d8674d..9a76ed8 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -45,6 +45,7 @@
 #include <asm/realmode.h>
 #include <asm/time.h>
 #include <asm/pgalloc.h>
+#include <asm/mem_encrypt.h>
 
 /*
  * We allocate runtime services regions bottom-up, starting from -4G, i.e.
@@ -286,7 +287,10 @@ 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;
 	}
@@ -329,6 +333,9 @@ 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",
@@ -455,6 +462,9 @@ 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);
 }
 
@@ -506,6 +516,9 @@ 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);
 	}
 }