linux-kernel - [PATCHv7 11/14] x86: Disable kexec if system has unaccepted memory

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Message-Id: <20220614120231.48165-12-kirill.shutemov@linux.intel.com>
Date:   Tue, 14 Jun 2022 15:02:28 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Borislav Petkov <bp@...en8.de>, Andy Lutomirski <luto@...nel.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Joerg Roedel <jroedel@...e.de>,
        Ard Biesheuvel <ardb@...nel.org>
Cc:     Andi Kleen <ak@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Tom Lendacky <thomas.lendacky@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Ingo Molnar <mingo@...hat.com>,
        Varad Gautam <varad.gautam@...e.com>,
        Dario Faggioli <dfaggioli@...e.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Mike Rapoport <rppt@...nel.org>,
        David Hildenbrand <david@...hat.com>,
        marcelo.cerri@...onical.com, tim.gardner@...onical.com,
        khalid.elmously@...onical.com, philip.cox@...onical.com,
        x86@...nel.org, linux-mm@...ck.org, linux-coco@...ts.linux.dev,
        linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCHv7 11/14] x86: Disable kexec if system has unaccepted memory

On kexec, the target kernel has to know what memory has been accepted.
Information in EFI map is out of date and cannot be used.

boot_params.unaccepted_memory can be used to pass the bitmap between two
kernels on kexec, but the use-case is not yet implemented.

Disable kexec on machines with unaccepted memory for now.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 arch/x86/mm/unaccepted_memory.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/arch/x86/mm/unaccepted_memory.c b/arch/x86/mm/unaccepted_memory.c
index bcd56fe82b9e..05e216716690 100644
--- a/arch/x86/mm/unaccepted_memory.c
+++ b/arch/x86/mm/unaccepted_memory.c
@@ -1,4 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-only
+#include <linux/kexec.h>
 #include <linux/memblock.h>
 #include <linux/mm.h>
 #include <linux/pfn.h>
@@ -95,3 +96,21 @@ bool range_contains_unaccepted_memory(phys_addr_t start, phys_addr_t end)
 
 	return ret;
 }
+
+static int __init unaccepted_init(void)
+{
+	if (!boot_params.unaccepted_memory)
+		return 0;
+
+#ifdef CONFIG_KEXEC_CORE
+	/*
+	 * TODO: Information on memory acceptance status has to be communicated
+	 * between kernel.
+	 */
+	pr_warn("Disable kexec: not yet supported on systems with unaccepted memory\n");
+	kexec_load_disabled = 1;
+#endif
+
+	return 0;
+}
+fs_initcall(unaccepted_init);
-- 
2.35.1