KVM: PPC: Book3S HV: Add guest->host real mode completion counters

Add counters to track number of times we switch from guest real mode
to host virtual mode during an interrupt-related hyper call because the
hypercall requires actions that cannot be completed in real mode. This
will help when making optimizations that reduce guest-host transitions.

It is safe to use an ordinary increment rather than an atomic operation
because there is one ICP per virtual CPU and kvmppc_xics_rm_complete()
only works on the ICP for the current VCPU.

The counters are displayed as part of IPC and ICP state provided by
/sys/debug/kernel/powerpc/kvm* for each VM.

Signed-off-by: Suresh Warrier <warrier@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/book3s_xics.h b/arch/powerpc/kvm/book3s_xics.h
index 73f0f2723c07..de970eca2167 100644
--- a/arch/powerpc/kvm/book3s_xics.h
+++ b/arch/powerpc/kvm/book3s_xics.h
@@ -78,6 +78,12 @@ struct kvmppc_icp {
 	u32  rm_reject;
 	u32  rm_eoied_irq;
 
+	/* Counters for each reason we exited real mode */
+	unsigned long n_rm_kick_vcpu;
+	unsigned long n_rm_check_resend;
+	unsigned long n_rm_reject;
+	unsigned long n_rm_notify_eoi;
+
 	/* Debug stuff for real mode */
 	union kvmppc_icp_state rm_dbgstate;
 	struct kvm_vcpu *rm_dbgtgt;