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Commit ead91d4b authored by Shai Fultheim's avatar Shai Fultheim Committed by Ingo Molnar
Browse files

x86/vsmp: Fix number of CPUs when vsmp is disabled 



In case CONFIG_X86_VSMP is not set, limit the number of CPUs to
the number of CPUs of the first board.

Also make CONFIG_X86_VSMP depend on CONFIG_SMP, as there's
little point in having a vsmp machine with a single CPU.

Signed-off-by: default avatarShai Fultheim <shai@scalemp.com>
[ido@wizery.com: rebased, fixed minor coding-style issues]
Signed-off-by: default avatarIdo Yariv <ido@wizery.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent b2d0b7a0

arch/x86/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -376,6 +376,7 @@ config X86_VSMP 
	select PARAVIRT

	depends on X86_64 && PCI

	depends on X86_EXTENDED_PLATFORM

	depends on SMP

	---help---

	  Support for ScaleMP vSMP systems.  Say 'Y' here if this kernel is

	  supposed to run on these EM64T-based machines.  Only choose this option

arch/x86/kernel/vsmp_64.c

+40 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/init.h>

#include <linux/pci_ids.h>

#include <linux/pci_regs.h>

#include <linux/smp.h>



#include <asm/apic.h>

#include <asm/pci-direct.h>
@@ -22,6 +23,8 @@ 
#include <asm/paravirt.h>

#include <asm/setup.h>



#define TOPOLOGY_REGISTER_OFFSET 0x10



#if defined CONFIG_PCI && defined CONFIG_PARAVIRT

/*

 * Interrupt control on vSMPowered systems:
@@ -149,12 +152,49 @@ int is_vsmp_box(void) 
	return 0;

}

#endif



static void __init vsmp_cap_cpus(void)

{

#if !defined(CONFIG_X86_VSMP) && defined(CONFIG_SMP)

	void __iomem *address;

	unsigned int cfg, topology, node_shift, maxcpus;



	/*

	 * CONFIG_X86_VSMP is not configured, so limit the number CPUs to the

	 * ones present in the first board, unless explicitly overridden by

	 * setup_max_cpus

	 */

	if (setup_max_cpus != NR_CPUS)

		return;



	/* Read the vSMP Foundation topology register */

	cfg = read_pci_config(0, 0x1f, 0, PCI_BASE_ADDRESS_0);

	address = early_ioremap(cfg + TOPOLOGY_REGISTER_OFFSET, 4);

	if (WARN_ON(!address))

		return;



	topology = readl(address);

	node_shift = (topology >> 16) & 0x7;

	if (!node_shift)

		/* The value 0 should be decoded as 8 */

		node_shift = 8;

	maxcpus = (topology & ((1 << node_shift) - 1)) + 1;



	pr_info("vSMP CTL: Capping CPUs to %d (CONFIG_X86_VSMP is unset)\n",

		maxcpus);

	setup_max_cpus = maxcpus;

	early_iounmap(address, 4);

#endif

}



void __init vsmp_init(void)

{

	detect_vsmp_box();

	if (!is_vsmp_box())

		return;



	vsmp_cap_cpus();



	set_vsmp_pv_ops();

	return;

}