This is a note to let you know that I've just added the patch titled

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

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: x86-boot-fix-boot-failure-when-smp-mp-table-is-based-at-0.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From ac5292e9a294618cecb31109d1ba265e3d027ba2 Mon Sep 17 00:00:00 2001

From: Tom Lendacky thomas.lendacky@amd.com Date: Mon, 6 Nov 2017 14:17:53 -0600 Subject: x86/boot: Fix boot failure when SMP MP-table is based at 0

From: Tom Lendacky thomas.lendacky@amd.com

commit ac5292e9a294618cecb31109d1ba265e3d027ba2 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: 5997efb96756 ("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.amdof... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/x86/kernel/mpparse.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/mpparse.c +++ b/arch/x86/kernel/mpparse.c @@ -431,6 +431,7 @@ static inline void __init construct_defa }

static unsigned long mpf_base; +static bool mpf_found;

static unsigned long __init get_mpc_size(unsigned long physptr) { @@ -504,7 +505,7 @@ void __init default_get_smp_config(unsig if (!smp_found_config) return;

- if (!mpf_base) + if (!mpf_found) return;

if (acpi_lapic && early) @@ -593,6 +594,7 @@ static int __init smp_scan_config(unsign smp_found_config = 1; #endif mpf_base = base; + mpf_found = true;

pr_info("found SMP MP-table at [mem %#010lx-%#010lx] mapped at [%p]\n", base, base + sizeof(*mpf) - 1, mpf); @@ -858,7 +860,7 @@ static int __init update_mp_table(void) if (!enable_update_mptable) return 0;

- if (!mpf_base) + if (!mpf_found) return 0;

mpf = early_memremap(mpf_base, sizeof(*mpf));

Patches currently in stable-queue which might be from thomas.lendacky@amd.com are

queue-4.14/x86-boot-fix-boot-failure-when-smp-mp-table-is-based-at-0.patch