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Date:   Fri, 27 Apr 2018 08:09:44 -0700
From:   tip-bot for Petr Tesarik <>
Subject: [tip:x86/urgent] x86/setup: Do not reserve a crash kernel region if
 booted on Xen PV

Commit-ID:  3db3eb285259ac129f7aec6b814b3e9f6c1b372b
Author:     Petr Tesarik <>
AuthorDate: Wed, 25 Apr 2018 12:08:35 +0200
Committer:  Thomas Gleixner <>
CommitDate: Fri, 27 Apr 2018 17:06:28 +0200

x86/setup: Do not reserve a crash kernel region if booted on Xen PV

Xen PV domains cannot shut down and start a crash kernel. Instead,
the crashing kernel makes a SCHEDOP_shutdown hypercall with the
reason code SHUTDOWN_crash, cf. xen_crash_shutdown() machine op in

A crash kernel reservation is merely a waste of RAM in this case. It
may also confuse users of kexec_load(2) and/or kexec_file_load(2).
respectively, these syscalls return success, which is technically
correct, but the crash kexec image will never be actually used.

Signed-off-by: Petr Tesarik <>
Signed-off-by: Thomas Gleixner <>
Reviewed-by: Juergen Gross <>
Cc: Tom Lendacky <>
Cc: Dou Liyang <>
Cc: Mikulas Patocka <>
Cc: Andy Lutomirski <>
Cc: "H. Peter Anvin" <>
Cc: Boris Ostrovsky <>
Cc: Borislav Petkov <>
Cc: Jean Delvare <>

 arch/x86/kernel/setup.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 6285697b6e56..5c623dfe39d1 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -50,6 +50,7 @@
 #include <linux/init_ohci1394_dma.h>
 #include <linux/kvm_para.h>
 #include <linux/dma-contiguous.h>
+#include <xen/xen.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
@@ -534,6 +535,11 @@ static void __init reserve_crashkernel(void)
 		high = true;
+	if (xen_pv_domain()) {
+		pr_info("Ignoring crashkernel for a Xen PV domain\n");
+		return;
+	}
 	/* 0 means: find the address automatically */
 	if (crash_base <= 0) {

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