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From:   "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To:     Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
        Sean Christopherson <seanjc@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Joerg Roedel <jroedel@suse.de>,
        Ard Biesheuvel <ardb@kernel.org>
Cc:     Andi Kleen <ak@linux.intel.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        David Rientjes <rientjes@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Ingo Molnar <mingo@redhat.com>,
        Dario Faggioli <dfaggioli@suse.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Mike Rapoport <rppt@kernel.org>,
        David Hildenbrand <david@redhat.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        marcelo.cerri@canonical.com, tim.gardner@canonical.com,
        khalid.elmously@canonical.com, philip.cox@canonical.com,
        aarcange@redhat.com, peterx@redhat.com, x86@kernel.org,
        linux-mm@kvack.org, linux-coco@lists.linux.dev,
        linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [PATCHv8 11/14] x86: Disable kexec if system has unaccepted memory
Date:   Wed,  7 Dec 2022 04:49:30 +0300
Message-Id: <20221207014933.8435-12-kirill.shutemov@linux.intel.com>
In-Reply-To: <20221207014933.8435-1-kirill.shutemov@linux.intel.com>
References: <20221207014933.8435-1-kirill.shutemov@linux.intel.com>
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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Information in EFI map is out of date and cannot be used.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@linux.intel.com>
---
 arch/x86/include/asm/kexec.h    |  5 +++++
 arch/x86/mm/unaccepted_memory.c | 16 ++++++++++++++++
 include/linux/kexec.h           |  7 +++++++
 kernel/kexec.c                  |  4 ++++
 kernel/kexec_file.c             |  4 ++++
 5 files changed, 36 insertions(+)

diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index a3760ca796aa..87abab578154 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -189,6 +189,11 @@ extern void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages);
 void arch_kexec_protect_crashkres(void);
 #define arch_kexec_protect_crashkres arch_kexec_protect_crashkres
 
+#ifdef CONFIG_UNACCEPTED_MEMORY
+int arch_kexec_load(void);
+#define arch_kexec_load arch_kexec_load
+#endif
+
 void arch_kexec_unprotect_crashkres(void);
 #define arch_kexec_unprotect_crashkres arch_kexec_unprotect_crashkres
 
diff --git a/arch/x86/mm/unaccepted_memory.c b/arch/x86/mm/unaccepted_memory.c
index a0a58486eb74..1745e6a65024 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>
@@ -98,3 +99,18 @@ bool range_contains_unaccepted_memory(phys_addr_t start, phys_addr_t end)
 
 	return ret;
 }
+
+#ifdef CONFIG_KEXEC_CORE
+int arch_kexec_load(void)
+{
+	if (!boot_params.unaccepted_memory)
+		return 0;
+
+	/*
+	 * TODO: Information on memory acceptance status has to be communicated
+	 * between kernel.
+	 */
+	pr_warn_once("Disable kexec: not yet supported on systems with unaccepted memory\n");
+	return -EOPNOTSUPP;
+}
+#endif
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 41a686996aaa..6b75051d5271 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -444,6 +444,13 @@ static inline void arch_kexec_protect_crashkres(void) { }
 static inline void arch_kexec_unprotect_crashkres(void) { }
 #endif
 
+#ifndef arch_kexec_load
+static inline int arch_kexec_load(void)
+{
+	return 0;
+}
+#endif
+
 #ifndef page_to_boot_pfn
 static inline unsigned long page_to_boot_pfn(struct page *page)
 {
diff --git a/kernel/kexec.c b/kernel/kexec.c
index cb8e6e6f983c..65dff44b487f 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -192,6 +192,10 @@ static inline int kexec_load_check(unsigned long nr_segments,
 {
 	int result;
 
+	result = arch_kexec_load();
+	if (result)
+		return result;
+
 	/* We only trust the superuser with rebooting the system. */
 	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
 		return -EPERM;
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 45637511e0de..8f1454c3776a 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -329,6 +329,10 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
 	int ret = 0, i;
 	struct kimage **dest_image, *image;
 
+	ret = arch_kexec_load();
+	if (ret)
+		return ret;
+
 	/* We only trust the superuser with rebooting the system. */
 	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
 		return -EPERM;
-- 
2.38.0