linux-kernel - [tip:x86/kdump] x86/kexec: Set the C-bit in the identity map page table when SEV is active

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Message-ID: <tip-85784d16c2cf172cf1ebaf2390d6b7c4045d659c@git.kernel.org>
Date:   Thu, 20 Jun 2019 03:02:34 -0700
From:   tip-bot for Lianbo Jiang <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     mingo@...nel.org, thomas.lendacky@....com, tglx@...utronix.de,
        x86@...nel.org, hpa@...or.com, bp@...e.de, lijiang@...hat.com,
        mingo@...hat.com, brijesh.singh@....com,
        kirill.shutemov@...ux.intel.com, akpm@...ux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: [tip:x86/kdump] x86/kexec: Set the C-bit in the identity map page
 table when SEV is active

Commit-ID:  85784d16c2cf172cf1ebaf2390d6b7c4045d659c
Gitweb:     https://git.kernel.org/tip/85784d16c2cf172cf1ebaf2390d6b7c4045d659c
Author:     Lianbo Jiang <lijiang@...hat.com>
AuthorDate: Tue, 30 Apr 2019 15:44:20 +0800
Committer:  Borislav Petkov <bp@...e.de>
CommitDate: Thu, 20 Jun 2019 10:07:12 +0200

x86/kexec: Set the C-bit in the identity map page table when SEV is active

When SEV is active, the second kernel image is loaded into encrypted
memory. For that, make sure that when kexec builds the identity mapping
page table, the memory is encrypted (i.e., _PAGE_ENC is set).

 [ bp: Sort local args and OR in _PAGE_ENC for more clarity. ]

Co-developed-by: Brijesh Singh <brijesh.singh@....com>
Signed-off-by: Brijesh Singh <brijesh.singh@....com>
Signed-off-by: Lianbo Jiang <lijiang@...hat.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: bhe@...hat.com
Cc: dyoung@...hat.com
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: kexec@...ts.infradead.org
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: x86-ml <x86@...nel.org>
Link: https://lkml.kernel.org/r/20190430074421.7852-3-lijiang@redhat.com
---
 arch/x86/kernel/machine_kexec_64.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 3b38449028e0..16c37fe489bc 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -50,12 +50,13 @@ static void free_transition_pgtable(struct kimage *image)
 
 static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
 {
+	pgprot_t prot = PAGE_KERNEL_EXEC_NOENC;
+	unsigned long vaddr, paddr;
+	int result = -ENOMEM;
 	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
-	unsigned long vaddr, paddr;
-	int result = -ENOMEM;
 
 	vaddr = (unsigned long)relocate_kernel;
 	paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
@@ -92,7 +93,11 @@ static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
 		set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
 	}
 	pte = pte_offset_kernel(pmd, vaddr);
-	set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC_NOENC));
+
+	if (sev_active())
+		prot = PAGE_KERNEL_EXEC;
+
+	set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
 	return 0;
 err:
 	return result;
@@ -129,6 +134,11 @@ static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
 	level4p = (pgd_t *)__va(start_pgtable);
 	clear_page(level4p);
 
+	if (sev_active()) {
+		info.page_flag   |= _PAGE_ENC;
+		info.kernpg_flag |= _PAGE_ENC;
+	}
+
 	if (direct_gbpages)
 		info.direct_gbpages = true;