From: Petr Tesarik <ptesarik@suse.cz>
To: x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
Borislav Petkov <bp@suse.de>, Juergen Gross <jgross@suse.com>,
Andy Lutomirski <luto@kernel.org>,
Mikulas Patocka <mpatocka@redhat.com>,
Jean Delvare <jdelvare@suse.de>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Dou Liyang <douly.fnst@cn.fujitsu.com>
Cc: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org
Subject: [PATCH] x86: Do not reserve a crash kernel region if booted on Xen PV
Date: Wed, 25 Apr 2018 12:08:35 +0200
Message-ID: <20180425120835.23cef60c@ezekiel.suse.cz> (raw)
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>
---
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) {
/*
--
2.13.6
next reply index
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-25 10:08 Petr Tesarik [this message]
2018-04-25 12:53 ` Juergen Gross
2018-04-27 15:09 ` [tip:x86/urgent] x86/setup: " tip-bot for Petr Tesarik
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