[PATCH 2/2] powerpc/smp: Add smp_muxed_ipi_rm_message_pass

[Suresh Warrier <warrier@linux.vnet.ibm.com>]

This function supports IPI message passing for real
mode callers.

Signed-off-by: Suresh Warrier <warrier@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/smp.h |  1 +
 arch/powerpc/kernel/smp.c      | 30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index 9ef9c37..851a37a 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -124,6 +124,7 @@ extern const char *smp_ipi_name[];
 /* for irq controllers with only a single ipi */
 extern void smp_muxed_ipi_set_data(int cpu, unsigned long data);
 extern void smp_muxed_ipi_message_pass(int cpu, int msg);
+extern void smp_muxed_ipi_rm_message_pass(int cpu, int msg);
 extern irqreturn_t smp_ipi_demux(void);
 
 void smp_init_pSeries(void);
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index a53a130..8c07bfad 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -53,6 +53,9 @@
 #include <asm/vdso.h>
 #include <asm/debug.h>
 #include <asm/kexec.h>
+#ifdef CONFIG_KVM_XICS
+#include <asm/xics.h>
+#endif
 
 #ifdef DEBUG
 #include <asm/udbg.h>
@@ -235,6 +238,33 @@ void smp_muxed_ipi_message_pass(int cpu, int msg)
 	smp_ops->cause_ipi(cpu, info->data);
 }
 
+#if defined(CONFIG_KVM_XICS) && defined(CONFIG_KVM_BOOK3S_HV_POSSIBLE)
+/*
+ * Message passing code for real mode callers. It does not use the
+ * smp_ops->cause_ipi function to cause an IPI, because those functions
+ * access the MFFR through an ioremapped address.
+ */
+void smp_muxed_ipi_rm_message_pass(int cpu, int msg)
+{
+	struct cpu_messages *info = &per_cpu(ipi_message, cpu);
+	char *message = (char *)&info->messages;
+	unsigned long xics_phys;
+
+	/*
+	 * Order previous accesses before accesses in the IPI handler.
+	 */
+	smp_mb();
+	message[msg] = 1;
+
+	/*
+	 * cause_ipi functions are required to include a full barrier
+	 * before doing whatever causes the IPI.
+	 */
+	xics_phys = paca[cpu].kvm_hstate.xics_phys;
+	out_rm8((u8 *)(xics_phys + XICS_MFRR), IPI_PRIORITY);
+}
+#endif
+
 #ifdef __BIG_ENDIAN__
 #define IPI_MESSAGE(A) (1uL << ((BITS_PER_LONG - 8) - 8 * (A)))
 #else
-- 
1.8.3.4