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x86/boot: Fix boot failure when SMP MP-table is based at 0

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commit ac5292e9a2 upstream.

When crosvm is used to boot a kernel as a VM, the SMP MP-table is found
at physical address 0x0. This causes mpf_base to be set to 0 and a
subsequent "if (!mpf_base)" check in default_get_smp_config() results in
the MP-table not being parsed.  Further into the boot this results in an
oops when attempting a read_apic_id().

Add a boolean variable that is set to true when the MP-table is found.
Use this variable for testing if the MP-table was found so that even a
value of 0 for mpf_base will result in continued parsing of the MP-table.

Fixes: 5997efb967 ("x86/boot: Use memremap() to map the MPF and MPC data")
Reported-by: Tomeu Vizoso <tomeu@tomeuvizoso.net>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: regression@leemhuis.info
Link: https://lkml.kernel.org/r/20171106201753.23059.86674.stgit@tlendack-t1.amdoffice.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tom Lendacky 2017-11-06 14:17:53 -06:00 • committed by Greg Kroah-Hartman
commit 46855f80d1
1 changed files with 4 additions and 2 deletions
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