From: Baoquan He <bhe@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: tglx@linutronix.de, mingo@kernel.org, bp@alien8.de,
hpa@zytor.com, kirill.shutemov@linux.intel.com, x86@kernel.org,
dyoung@redhat.com
Subject: [PATCH v5 2/3] x86/kexec/64: Error out if try to jump to old 4-level kernel from 5-level kernel
Date: Thu, 9 May 2019 15:02:57 +0800 [thread overview]
Message-ID: <20190509070257.GF24922@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20190509013644.1246-3-bhe@redhat.com>
If the running kernel has 5-level paging activated, the 5-level paging
mode is preserved across kexec. If the kexec'ed kernel does not contain
support for handling active 5-level paging mode in the decompressor, the
decompressor will crash with #GP.
Prevent this situation at load time. If 5-level paging is active, check the
xloadflags whether the kexec kernel can handle 5-level paging at least in
the decompressor. If not, reject the load attempt and print out error
message.
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
v4->v5:
Update the output error message per tglx's comment.
arch/x86/kernel/kexec-bzimage64.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 22f60dd26460..7f439739ea3d 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -321,6 +321,11 @@ static int bzImage64_probe(const char *buf, unsigned long len)
return ret;
}
+ if (!(header->xloadflags & XLF_5LEVEL) && pgtable_l5_enabled()) {
+ pr_err("bzImage cannot handle 5-level paging mode.\n");
+ return ret;
+ }
+
/* I've got a bzImage */
pr_debug("It's a relocatable bzImage64\n");
ret = 0;
--
2.17.2
next prev parent reply other threads:[~2019-05-09 7:03 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-09 1:36 [PATCH v4 0/3] Add restrictions for kexec/kdump jumping between 5-level and 4-level kernel Baoquan He
2019-05-09 1:36 ` [PATCH v4 1/3] x86/boot: Add xloadflags bits for 5-level kernel checking Baoquan He
2019-05-09 1:36 ` [PATCH v4 2/3] x86/kexec/64: Error out if try to jump to old 4-level kernel from 5-level kernel Baoquan He
2019-05-09 7:01 ` Baoquan He
2019-05-09 7:02 ` Baoquan He [this message]
2019-05-22 3:20 ` Dave Young
2019-05-22 3:24 ` Dave Young
2019-05-22 4:50 ` Baoquan He
2019-05-09 1:36 ` [PATCH v4 3/3] x86/kdump/64: Change the upper limit of crashkernel reservation Baoquan He
2019-05-22 3:11 ` Dave Young
2019-05-22 3:15 ` Baoquan He
2019-05-23 3:15 ` Baoquan He
2019-05-24 7:38 [PATCH v5 0/3] Add restrictions for kexec/kdump jumping between 5-level and 4-level kernel Baoquan He
2019-05-24 7:38 ` [PATCH v5 2/3] x86/kexec/64: Error out if try to jump to old 4-level kernel from 5-level kernel Baoquan He
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