xen: support CONFIG_MAXSMP (900cba88) · Commits · 戴 / test

The MAXSMP config option requires CPUMASK_OFFSTACK, which in turn requires we init the memory for the maps while we bring up the cpus. MAXSMP also increases NR_CPUS to 4096. This increase in size exposed an issue in the argument construction for multicalls from xen_flush_tlb_others. The args should only need space for the actual number of cpus. Also in 2.6.39 it exposes a bootup problem. BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<ffffffff8157a1d3>] set_cpu_sibling_map+0x123/0x30d ... Call Trace: [<ffffffff81039a3f>] ? xen_restore_fl_direct_reloc+0x4/0x4 [<ffffffff819dc4db>] xen_smp_prepare_cpus+0x36/0x135 .. CC: stable@kernel.org Signed-off-by:

Andrew Jones <drjones@redhat.com> [v2: Updated to compile on 3.0] [v3: Updated to compile when CONFIG_SMP is not defined] Signed-off-by:

Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/xen/mmu.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -59,6 +59,7 @@
		#include <asm/page.h>
		#include <asm/init.h>
		#include <asm/pat.h>
		#include <asm/smp.h>

		#include <asm/xen/hypercall.h>
		#include <asm/xen/hypervisor.h>
		@@ -1231,7 +1232,7 @@ static void xen_flush_tlb_others(const struct cpumask *cpus,
		{
		struct {
		struct mmuext_op op;
		DECLARE_BITMAP(mask, NR_CPUS);
		DECLARE_BITMAP(mask, num_processors);
		} *args;
		struct multicall_space mcs;

arch/x86/xen/smp.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -205,11 +205,18 @@ static void __init xen_smp_prepare_boot_cpu(void)
		static void __init xen_smp_prepare_cpus(unsigned int max_cpus)
		{
		unsigned cpu;
		unsigned int i;

		xen_init_lock_cpu(0);

		smp_store_cpu_info(0);
		cpu_data(0).x86_max_cores = 1;

		for_each_possible_cpu(i) {
		zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
		zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
		zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
		}
		set_cpu_sibling_map(0);

		if (xen_smp_intr_init(0))

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