powerpc/kvm/book3s_hv: Rework the secondary inhibit code

As part of the support for split core on POWER8, we want to be able to
block splitting of the core while KVM VMs are active.

The logic to do that would be exactly the same as the code we currently
have for inhibiting onlining of secondaries.

Instead of adding an identical mechanism to block split core, rework the
secondary inhibit code to be a "HV KVM is active" check. We can then use
that in both the cpu hotplug code and the upcoming split core code.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Acked-by: Alexander Graf <agraf@suse.de>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 3 insertions, 31 deletions

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 4863ea14f270..5cdd9eb3b24c 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -36,6 +36,7 @@
 #include <linux/atomic.h>
 #include <asm/irq.h>
 #include <asm/hw_irq.h>
+#include <asm/kvm_ppc.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/prom.h>
@@ -458,38 +459,9 @@ int generic_check_cpu_restart(unsigned int cpu)
         return per_cpu(cpu_state, cpu) == CPU_UP_PREPARE;
 }
 
-static atomic_t secondary_inhibit_count;
-
-/*
- * Don't allow secondary CPU threads to come online
- */
-void inhibit_secondary_onlining(void)
-{
-        /*
-         * This makes secondary_inhibit_count stable during cpu
-         * online/offline operations.
-         */
-        get_online_cpus();
-
-        atomic_inc(&secondary_inhibit_count);
-        put_online_cpus();
-}
-EXPORT_SYMBOL_GPL(inhibit_secondary_onlining);
-
-/*
- * Allow secondary CPU threads to come online again
- */
-void uninhibit_secondary_onlining(void)
-{
-        get_online_cpus();
-        atomic_dec(&secondary_inhibit_count);
-        put_online_cpus();
-}
-EXPORT_SYMBOL_GPL(uninhibit_secondary_onlining);
-
-static int secondaries_inhibited(void)
+static bool secondaries_inhibited(void)
 {
-        return atomic_read(&secondary_inhibit_count);
+        return kvm_hv_mode_active();
 }
 
 #else /* HOTPLUG_CPU */