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

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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
arch/x86/xen/enlighten_pv.c.

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).
When flags include KEXEC_ON_CRASH or KEXEC_FILE_ON_CRASH,
respectively, these syscalls return success, which is technically
correct, but the crash kexec image will never be actually used.

Signed-off-by: Petr Tesarik <ptesarik@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Dou Liyang <douly.fnst@cn.fujitsu.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: xen-devel@lists.xenproject.org
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Jean Delvare <jdelvare@suse.de>
Link: https://lkml.kernel.org/r/20180425120835.23cef60c@ezekiel.suse.cz
This commit is contained in:
Petr Tesarik 2018-04-25 12:08:35 +02:00 committed by Thomas Gleixner
parent b837913fc2
commit 3db3eb2852
1 changed files with 6 additions and 0 deletions
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6
arch/x86/kernel/setup.c
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@ -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) {
/*