linux-kernel - [RFC PATCH v1 09/28] x86/efi: Access EFI data as encrypted when SEV is active

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Message-ID: <147190832511.9523.10850626471583956499.stgit@brijesh-build-machine>
Date:   Mon, 22 Aug 2016 19:25:25 -0400
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>,
        <linus.walleij@...aro.org>, <linux-mm@...ck.org>,
        <paul.gortmaker@...driver.com>, <hpa@...or.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>,
        <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>, <toshi.kani@....com>,
        <mathieu.desnoyers@...icios.com>, <devel@...uxdriverproject.org>,
        <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>, <linux-crypto@...r.kernel.org>,
        <pbonzini@...hat.com>, <akpm@...ux-foundation.org>,
        <davem@...emloft.net>
Subject: [RFC PATCH v1 09/28] 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>
---
 arch/x86/platform/efi/efi_64.c |   14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 0871ea4..98363f3 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -213,7 +213,7 @@ void efi_sync_low_kernel_mappings(void)
 
 int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
 {
-	unsigned long pfn, text;
+	unsigned long pfn, text, flags;
 	efi_memory_desc_t *md;
 	struct page *page;
 	unsigned npages;
@@ -230,6 +230,10 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
 	efi_scratch.efi_pgt = (pgd_t *)__sme_pa(efi_pgd);
 	pgd = efi_pgd;
 
+	flags = _PAGE_NX | _PAGE_RW;
+	if (sev_active)
+		flags |= _PAGE_ENC;
+
 	/*
 	 * It can happen that the physical address of new_memmap lands in memory
 	 * which is not mapped in the EFI page table. Therefore we need to go
@@ -237,7 +241,7 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
 	 * phys_efi_set_virtual_address_map().
 	 */
 	pfn = pa_memmap >> PAGE_SHIFT;
-	if (kernel_map_pages_in_pgd(pgd, pfn, pa_memmap, num_pages, _PAGE_NX | _PAGE_RW)) {
+	if (kernel_map_pages_in_pgd(pgd, pfn, pa_memmap, num_pages, flags)) {
 		pr_err("Error ident-mapping new memmap (0x%lx)!\n", pa_memmap);
 		return 1;
 	}
@@ -302,6 +306,9 @@ 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",
@@ -426,6 +433,9 @@ void __init efi_runtime_update_mappings(void)
 			(md->type != EFI_RUNTIME_SERVICES_CODE))
 			pf |= _PAGE_RW;
 
+		if (sev_active)
+			pf |= _PAGE_ENC;
+
 		/* Update the 1:1 mapping */
 		pfn = md->phys_addr >> PAGE_SHIFT;
 		if (kernel_map_pages_in_pgd(pgd, pfn, md->phys_addr, md->num_pages, pf))