1 files changed, 262 insertions, 0 deletions
diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
new file mode 100644
index 000000000..affbff65e
--- /dev/null
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -0,0 +1,262 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/cpuhotplug.h>
+#include <linux/cpumask.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+
+#include <asm/apic.h>
+
+#include "local.h"
+
+#define apic_cluster(apicid) ((apicid) >> 4)
+
+/*
+ * __x2apic_send_IPI_mask() possibly needs to read
+ * x86_cpu_to_logical_apicid for all online cpus in a sequential way.
+ * Using per cpu variable would cost one cache line per cpu.
+ */
+static u32 *x86_cpu_to_logical_apicid __read_mostly;
+
+static DEFINE_PER_CPU(cpumask_var_t, ipi_mask);
+static DEFINE_PER_CPU_READ_MOSTLY(struct cpumask *, cluster_masks);
+
+static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
+{
+	return x2apic_enabled();
+}
+
+static void x2apic_send_IPI(int cpu, int vector)
+{
+	u32 dest = x86_cpu_to_logical_apicid[cpu];
+
+	/* x2apic MSRs are special and need a special fence: */
+	weak_wrmsr_fence();
+	__x2apic_send_IPI_dest(dest, vector, APIC_DEST_LOGICAL);
+}
+
+static void
+__x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int apic_dest)
+{
+	unsigned int cpu, clustercpu;
+	struct cpumask *tmpmsk;
+	unsigned long flags;
+	u32 dest;
+
+	/* x2apic MSRs are special and need a special fence: */
+	weak_wrmsr_fence();
+	local_irq_save(flags);
+
+	tmpmsk = this_cpu_cpumask_var_ptr(ipi_mask);
+	cpumask_copy(tmpmsk, mask);
+	/* If IPI should not be sent to self, clear current CPU */
+	if (apic_dest != APIC_DEST_ALLINC)
+		__cpumask_clear_cpu(smp_processor_id(), tmpmsk);
+
+	/* Collapse cpus in a cluster so a single IPI per cluster is sent */
+	for_each_cpu(cpu, tmpmsk) {
+		struct cpumask *cmsk = per_cpu(cluster_masks, cpu);
+
+		dest = 0;
+		for_each_cpu_and(clustercpu, tmpmsk, cmsk)
+			dest |= x86_cpu_to_logical_apicid[clustercpu];
+
+		if (!dest)
+			continue;
+
+		__x2apic_send_IPI_dest(dest, vector, APIC_DEST_LOGICAL);
+		/* Remove cluster CPUs from tmpmask */
+		cpumask_andnot(tmpmsk, tmpmsk, cmsk);
+	}
+
+	local_irq_restore(flags);
+}
+
+static void x2apic_send_IPI_mask(const struct cpumask *mask, int vector)
+{
+	__x2apic_send_IPI_mask(mask, vector, APIC_DEST_ALLINC);
+}
+
+static void
+x2apic_send_IPI_mask_allbutself(const struct cpumask *mask, int vector)
+{
+	__x2apic_send_IPI_mask(mask, vector, APIC_DEST_ALLBUT);
+}
+
+static u32 x2apic_calc_apicid(unsigned int cpu)
+{
+	return x86_cpu_to_logical_apicid[cpu];
+}
+
+static void init_x2apic_ldr(void)
+{
+	struct cpumask *cmsk = this_cpu_read(cluster_masks);
+
+	BUG_ON(!cmsk);
+
+	cpumask_set_cpu(smp_processor_id(), cmsk);
+}
+
+/*
+ * As an optimisation during boot, set the cluster_mask for all present
+ * CPUs at once, to prevent each of them having to iterate over the others
+ * to find the existing cluster_mask.
+ */
+static void prefill_clustermask(struct cpumask *cmsk, unsigned int cpu, u32 cluster)
+{
+	int cpu_i;
+
+	for_each_present_cpu(cpu_i) {
+		struct cpumask **cpu_cmsk = &per_cpu(cluster_masks, cpu_i);
+		u32 apicid = apic->cpu_present_to_apicid(cpu_i);
+
+		if (apicid == BAD_APICID || cpu_i == cpu || apic_cluster(apicid) != cluster)
+			continue;
+
+		if (WARN_ON_ONCE(*cpu_cmsk == cmsk))
+			continue;
+
+		BUG_ON(*cpu_cmsk);
+		*cpu_cmsk = cmsk;
+	}
+}
+
+static int alloc_clustermask(unsigned int cpu, u32 cluster, int node)
+{
+	struct cpumask *cmsk = NULL;
+	unsigned int cpu_i;
+
+	/*
+	 * At boot time, the CPU present mask is stable. The cluster mask is
+	 * allocated for the first CPU in the cluster and propagated to all
+	 * present siblings in the cluster. If the cluster mask is already set
+	 * on entry to this function for a given CPU, there is nothing to do.
+	 */
+	if (per_cpu(cluster_masks, cpu))
+		return 0;
+
+	if (system_state < SYSTEM_RUNNING)
+		goto alloc;
+
+	/*
+	 * On post boot hotplug for a CPU which was not present at boot time,
+	 * iterate over all possible CPUs (even those which are not present
+	 * any more) to find any existing cluster mask.
+	 */
+	for_each_possible_cpu(cpu_i) {
+		u32 apicid = apic->cpu_present_to_apicid(cpu_i);
+
+		if (apicid != BAD_APICID && apic_cluster(apicid) == cluster) {
+			cmsk = per_cpu(cluster_masks, cpu_i);
+			/*
+			 * If the cluster is already initialized, just store
+			 * the mask and return. There's no need to propagate.
+			 */
+			if (cmsk) {
+				per_cpu(cluster_masks, cpu) = cmsk;
+				return 0;
+			}
+		}
+	}
+	/*
+	 * No CPU in the cluster has ever been initialized, so fall through to
+	 * the boot time code which will also populate the cluster mask for any
+	 * other CPU in the cluster which is (now) present.
+	 */
+alloc:
+	cmsk = kzalloc_node(sizeof(*cmsk), GFP_KERNEL, node);
+	if (!cmsk)
+		return -ENOMEM;
+	per_cpu(cluster_masks, cpu) = cmsk;
+	prefill_clustermask(cmsk, cpu, cluster);
+
+	return 0;
+}
+
+static int x2apic_prepare_cpu(unsigned int cpu)
+{
+	u32 phys_apicid = apic->cpu_present_to_apicid(cpu);
+	u32 cluster = apic_cluster(phys_apicid);
+	u32 logical_apicid = (cluster << 16) | (1 << (phys_apicid & 0xf));
+
+	x86_cpu_to_logical_apicid[cpu] = logical_apicid;
+
+	if (alloc_clustermask(cpu, cluster, cpu_to_node(cpu)) < 0)
+		return -ENOMEM;
+	if (!zalloc_cpumask_var(&per_cpu(ipi_mask, cpu), GFP_KERNEL))
+		return -ENOMEM;
+	return 0;
+}
+
+static int x2apic_dead_cpu(unsigned int dead_cpu)
+{
+	struct cpumask *cmsk = per_cpu(cluster_masks, dead_cpu);
+
+	if (cmsk)
+		cpumask_clear_cpu(dead_cpu, cmsk);
+	free_cpumask_var(per_cpu(ipi_mask, dead_cpu));
+	return 0;
+}
+
+static int x2apic_cluster_probe(void)
+{
+	u32 slots;
+
+	if (!x2apic_mode)
+		return 0;
+
+	slots = max_t(u32, L1_CACHE_BYTES/sizeof(u32), nr_cpu_ids);
+	x86_cpu_to_logical_apicid = kcalloc(slots, sizeof(u32), GFP_KERNEL);
+	if (!x86_cpu_to_logical_apicid)
+		return 0;
+
+	if (cpuhp_setup_state(CPUHP_X2APIC_PREPARE, "x86/x2apic:prepare",
+			      x2apic_prepare_cpu, x2apic_dead_cpu) < 0) {
+		pr_err("Failed to register X2APIC_PREPARE\n");
+		kfree(x86_cpu_to_logical_apicid);
+		x86_cpu_to_logical_apicid = NULL;
+		return 0;
+	}
+	init_x2apic_ldr();
+	return 1;
+}
+
+static struct apic apic_x2apic_cluster __ro_after_init = {
+
+	.name				= "cluster x2apic",
+	.probe				= x2apic_cluster_probe,
+	.acpi_madt_oem_check		= x2apic_acpi_madt_oem_check,
+
+	.delivery_mode			= APIC_DELIVERY_MODE_FIXED,
+	.dest_mode_logical		= true,
+
+	.disable_esr			= 0,
+
+	.check_apicid_used		= NULL,
+	.init_apic_ldr			= init_x2apic_ldr,
+	.ioapic_phys_id_map		= NULL,
+	.cpu_present_to_apicid		= default_cpu_present_to_apicid,
+	.phys_pkg_id			= x2apic_phys_pkg_id,
+
+	.max_apic_id			= UINT_MAX,
+	.x2apic_set_max_apicid		= true,
+	.get_apic_id			= x2apic_get_apic_id,
+	.set_apic_id			= x2apic_set_apic_id,
+
+	.calc_dest_apicid		= x2apic_calc_apicid,
+
+	.send_IPI			= x2apic_send_IPI,
+	.send_IPI_mask			= x2apic_send_IPI_mask,
+	.send_IPI_mask_allbutself	= x2apic_send_IPI_mask_allbutself,
+	.send_IPI_allbutself		= x2apic_send_IPI_allbutself,
+	.send_IPI_all			= x2apic_send_IPI_all,
+	.send_IPI_self			= x2apic_send_IPI_self,
+
+	.read				= native_apic_msr_read,
+	.write				= native_apic_msr_write,
+	.eoi				= native_apic_msr_eoi,
+	.icr_read			= native_x2apic_icr_read,
+	.icr_write			= native_x2apic_icr_write,
+};
+
+apic_driver(apic_x2apic_cluster);