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-rw-r--r--arch/x86/kernel/vsmp_64.c40
1 files changed, 40 insertions, 0 deletions
diff --git a/arch/x86/kernel/vsmp_64.c b/arch/x86/kernel/vsmp_64.c
index a1d804bcd483..8eeb55a551b4 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 +152,49 @@ 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;
}