Commit ac5292e9 authored by Tom Lendacky's avatar Tom Lendacky Committed by Thomas Gleixner

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

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: 5997efb9 ("x86/boot: Use memremap() to map the MPF and MPC data")
Reported-by: default avatarTomeu Vizoso <tomeu@tomeuvizoso.net>
Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: regression@leemhuis.info
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20171106201753.23059.86674.stgit@tlendack-t1.amdoffice.net
parent be62a320
...@@ -431,6 +431,7 @@ static inline void __init construct_default_ISA_mptable(int mpc_default_type) ...@@ -431,6 +431,7 @@ static inline void __init construct_default_ISA_mptable(int mpc_default_type)
} }
static unsigned long mpf_base; static unsigned long mpf_base;
static bool mpf_found;
static unsigned long __init get_mpc_size(unsigned long physptr) static unsigned long __init get_mpc_size(unsigned long physptr)
{ {
...@@ -504,7 +505,7 @@ void __init default_get_smp_config(unsigned int early) ...@@ -504,7 +505,7 @@ void __init default_get_smp_config(unsigned int early)
if (!smp_found_config) if (!smp_found_config)
return; return;
if (!mpf_base) if (!mpf_found)
return; return;
if (acpi_lapic && early) if (acpi_lapic && early)
...@@ -593,6 +594,7 @@ static int __init smp_scan_config(unsigned long base, unsigned long length) ...@@ -593,6 +594,7 @@ static int __init smp_scan_config(unsigned long base, unsigned long length)
smp_found_config = 1; smp_found_config = 1;
#endif #endif
mpf_base = base; mpf_base = base;
mpf_found = true;
pr_info("found SMP MP-table at [mem %#010lx-%#010lx] mapped at [%p]\n", pr_info("found SMP MP-table at [mem %#010lx-%#010lx] mapped at [%p]\n",
base, base + sizeof(*mpf) - 1, mpf); base, base + sizeof(*mpf) - 1, mpf);
...@@ -858,7 +860,7 @@ static int __init update_mp_table(void) ...@@ -858,7 +860,7 @@ static int __init update_mp_table(void)
if (!enable_update_mptable) if (!enable_update_mptable)
return 0; return 0;
if (!mpf_base) if (!mpf_found)
return 0; return 0;
mpf = early_memremap(mpf_base, sizeof(*mpf)); mpf = early_memremap(mpf_base, sizeof(*mpf));
......
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