Add a new ipi_cpu() function to the MI IPI API that can be used to send an

IPI to a specific CPU by its cpuid.  Replace calls to ipi_selected() that
constructed a mask for a single CPU with calls to ipi_cpu() instead.  This
will matter more in the future when we transition from cpumask_t to
cpuset_t for CPU masks in which case building a CPU mask is more expensive.

Submitted by:	peter, sbruno
Reviewed by:	rookie
Obtained from:	Yahoo! (x86)
MFC after:	1 month

1 files changed, 39 insertions, 3 deletions

diff --git a/sys/amd64/amd64/mp_machdep.c b/sys/amd64/amd64/mp_machdep.c
index 22ad40a..64e9880 100644
--- a/sys/amd64/amd64/mp_machdep.c
+++ b/sys/amd64/amd64/mp_machdep.c
@@ -1239,15 +1239,51 @@ ipi_selected(cpumask_t cpus, u_int ipi)
 			do {
 				old_pending = cpu_ipi_pending[cpu];
 				new_pending = old_pending | bitmap;
-			} while  (!atomic_cmpset_int(&cpu_ipi_pending[cpu],old_pending, new_pending));	
-
+			} while  (!atomic_cmpset_int(&cpu_ipi_pending[cpu],
+			    old_pending, new_pending));	
 			if (old_pending)
 				continue;
 		}
-
 		lapic_ipi_vectored(ipi, cpu_apic_ids[cpu]);
 	}
+}
+
+/*
+ * send an IPI to a specific CPU.
+ */
+void
+ipi_cpu(int cpu, u_int ipi)
+{
+	u_int bitmap = 0;
+	u_int old_pending;
+	u_int new_pending;
+
+	if (IPI_IS_BITMAPED(ipi)) { 
+		bitmap = 1 << ipi;
+		ipi = IPI_BITMAP_VECTOR;
+	}
 
+	/*
+	 * IPI_STOP_HARD maps to a NMI and the trap handler needs a bit
+	 * of help in order to understand what is the source.
+	 * Set the mask of receiving CPUs for this purpose.
+	 */
+	if (ipi == IPI_STOP_HARD)
+		atomic_set_int(&ipi_nmi_pending, 1 << cpu);
+
+	CTR3(KTR_SMP, "%s: cpu: %d ipi: %x", __func__, cpu, ipi);
+	KASSERT(cpu_apic_ids[cpu] != -1, ("IPI to non-existent CPU %d", cpu));
+
+	if (bitmap) {
+		do {
+			old_pending = cpu_ipi_pending[cpu];
+			new_pending = old_pending | bitmap;
+		} while  (!atomic_cmpset_int(&cpu_ipi_pending[cpu],
+		    old_pending, new_pending));	
+		if (old_pending)
+			return;
+	}
+	lapic_ipi_vectored(ipi, cpu_apic_ids[cpu]);
 }
 
 /*