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Subject[PATCH v2 1/2] vsmp: Fix number of CPUs when vsmp is disabled
Date
From: Shai Fultheim <shai@scalemp.com>

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

Signed-off-by: Shai Fultheim <shai@scalemp.com>
[ido@wizery.com: rebased, fixed minor coding-style issues]
Signed-off-by: Ido Yariv <ido@wizery.com>
---
arch/x86/kernel/vsmp_64.c | 48 +++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 48 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/vsmp_64.c b/arch/x86/kernel/vsmp_64.c
index a1d804b..61571fd 100644
--- a/arch/x86/kernel/vsmp_64.c
+++ b/arch/x86/kernel/vsmp_64.c
@@ -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 +152,57 @@ int is_vsmp_box(void)
return 0;
}
#endif
+
+#ifdef CONFIG_X86_VSMP
+
+static void __init vsmp_cap_cpus(void)
+{
+ /* VSMP is enabled, no need to cap cpus */
+}
+
+#else
+
+static void __init vsmp_cap_cpus(void)
+{
+ /*
+ * 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) {
+ void __iomem *address;
+ unsigned int cfg, topology, node_shift, maxcpus;
+
+ /* 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;
+
+ printk(KERN_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;
}
--
1.7.7.6


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