s390/early: improve machine detection (03aa047e) · Commits · 戴 / test

Right now the early machine detection code check stsi 3.2.2 for "KVM" and set MACHINE_IS_VM if this is different. As the console detection uses diagnose 8 if MACHINE_IS_VM returns true this will crash Linux early for any non z/VM system that sets a different value than KVM. So instead of assuming z/VM, do not set any of MACHINE_IS_LPAR, MACHINE_IS_VM, or MACHINE_IS_KVM. CC: stable@vger.kernel.org Reviewed-by:

Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by:

Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by:

Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/early.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -63,10 +63,10 @@ static noinline __init void detect_machine_type(void)
		if (stsi(vmms, 3, 2, 2) \|\| !vmms->count)
		return;

		/* Running under KVM? If not we assume z/VM */
		/* Detect known hypervisors */
		if (!memcmp(vmms->vm[0].cpi, "\xd2\xe5\xd4", 3))
		S390_lowcore.machine_flags \|= MACHINE_FLAG_KVM;
		else
		else if (!memcmp(vmms->vm[0].cpi, "\xa9\x61\xe5\xd4", 4))
		S390_lowcore.machine_flags \|= MACHINE_FLAG_VM;
		}

arch/s390/kernel/setup.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1006,6 +1006,8 @@ void __init setup_arch(char **cmdline_p)
		pr_info("Linux is running under KVM in 64-bit mode\n");
		else if (MACHINE_IS_LPAR)
		pr_info("Linux is running natively in 64-bit mode\n");
		else
		pr_info("Linux is running as a guest in 64-bit mode\n");

		/* Have one command line that is parsed and saved in /proc/cmdline */
		/* boot_command_line has been already set up in early.c */

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