Messages in this thread Patch in this message | | | From | Russ Dill <> | Subject | [PATCH] x86/boot: Fail gracefully if SMP MP-table early_memremap fails | Date | Fri, 19 Aug 2022 15:44:00 -0700 |
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At least one older motherboard (Micronics W6-LI Pentium Pro) has been observed to fill in the physptr but not actually populate the mpc when only one CPU is present. In this specific case, this leads to the size field being zero which causes early_memremap to fail. This then causes a NULL pointer exception in smp_read_mpc.
Add a simple return check. Returning -1 here will cause the MP-table to be ignored and the system to boot in nosmp mode.
Signed-off-by: Russ Dill <Russ.Dill@gmail.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: x86@kernel.org --- arch/x86/kernel/mpparse.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/arch/x86/kernel/mpparse.c b/arch/x86/kernel/mpparse.c index fed721f90116..ca2af4f42cb8 100644 --- a/arch/x86/kernel/mpparse.c +++ b/arch/x86/kernel/mpparse.c @@ -438,6 +438,10 @@ static int __init check_physptr(struct mpf_intel *mpf, unsigned int early) size = get_mpc_size(mpf->physptr); mpc = early_memremap(mpf->physptr, size); + if (!mpc) { + pr_err("MPTABLE: mpc early_memremap() failed\n"); + return -1; + } /* * Read the physical hardware table. Anything here will -- 2.36.1
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