powerpc/xive: Native exploitation of the XIVE interrupt controller

The XIVE interrupt controller is the new interrupt controller
found in POWER9. It supports advanced virtualization capabilities
among other things.

Currently we use a set of firmware calls that simulate the old
"XICS" interrupt controller but this is fairly inefficient.

This adds the framework for using XIVE along with a native
backend which OPAL for configuration. Later, a backend allowing
the use in a KVM or PowerVM guest will also be provided.

This disables some fast path for interrupts in KVM when XIVE is
enabled as these rely on the firmware emulation code which is no
longer available when the XIVE is used natively by Linux.

A latter patch will make KVM also directly exploit the XIVE, thus
recovering the lost performance (and more).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[mpe: Fixup pr_xxx("XIVE:"...), don't split pr_xxx() strings,
 tweak Kconfig so XIVE_NATIVE selects XIVE and depends on POWERNV,
 fix build errors when SMP=n, fold in fixes from Ben:
   Don't call cpu_online() on an invalid CPU number
   Fix irq target selection returning out of bounds cpu#
   Extra sanity checks on cpu numbers
 ]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c
index 4d6c64b3041c..ae55603cf661 100644
--- a/arch/powerpc/kvm/book3s_hv_builtin.c
+++ b/arch/powerpc/kvm/book3s_hv_builtin.c
@@ -23,6 +23,7 @@
 #include <asm/kvm_book3s.h>
 #include <asm/archrandom.h>
 #include <asm/xics.h>
+#include <asm/xive.h>
 #include <asm/dbell.h>
 #include <asm/cputhreads.h>
 #include <asm/io.h>
@@ -224,6 +225,10 @@ void kvmhv_rm_send_ipi(int cpu)
 		return;
 	}
 
+	/* We should never reach this */
+	if (WARN_ON_ONCE(xive_enabled()))
+	    return;
+
 	/* Else poke the target with an IPI */
 	xics_phys = paca[cpu].kvm_hstate.xics_phys;
 	if (xics_phys)
@@ -386,6 +391,9 @@ long kvmppc_read_intr(void)
 	long rc;
 	bool again;
 
+	if (xive_enabled())
+		return 1;
+
 	do {
 		again = false;
 		rc = kvmppc_read_one_intr(&again);