KVM: PPC: Book3S HV: Speed up wakeups of CPUs on HV KVM
Currently, we wake up a CPU by sending a host IPI with
smp_send_reschedule() to thread 0 of that core, which will take all
threads out of the guest, and cause them to re-evaluate their
interrupt status on the way back in.
This adds a mechanism to differentiate real host IPIs from IPIs sent
by KVM for guest threads to poke each other, in order to target the
guest threads precisely when possible and avoid that global switch of
the core to host state.
We then use this new facility in the in-kernel XICS code.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/arch/powerpc/sysdev/xics/icp-native.c b/arch/powerpc/sysdev/xics/icp-native.c
index 48861d3..20b328b 100644
--- a/arch/powerpc/sysdev/xics/icp-native.c
+++ b/arch/powerpc/sysdev/xics/icp-native.c
@@ -51,6 +51,12 @@
static inline unsigned int icp_native_get_xirr(void)
{
int cpu = smp_processor_id();
+ unsigned int xirr;
+
+ /* Handled an interrupt latched by KVM */
+ xirr = kvmppc_get_xics_latch();
+ if (xirr)
+ return xirr;
return in_be32(&icp_native_regs[cpu]->xirr.word);
}
@@ -138,6 +144,7 @@
static void icp_native_cause_ipi(int cpu, unsigned long data)
{
+ kvmppc_set_host_ipi(cpu, 1);
icp_native_set_qirr(cpu, IPI_PRIORITY);
}
@@ -151,6 +158,7 @@
{
int cpu = smp_processor_id();
+ kvmppc_set_host_ipi(cpu, 0);
icp_native_set_qirr(cpu, 0xff);
return smp_ipi_demux();