1 files changed, 328 insertions, 0 deletions
diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c
new file mode 100644
index 0000000000..97bfe5f053
--- /dev/null
+++ b/arch/x86/hyperv/hv_apic.c
@@ -0,0 +1,328 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Hyper-V specific APIC code.
+ *
+ * Copyright (C) 2018, Microsoft, Inc.
+ *
+ * Author : K. Y. Srinivasan <kys@microsoft.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/clockchips.h>
+#include <linux/hyperv.h>
+#include <linux/slab.h>
+#include <linux/cpuhotplug.h>
+#include <asm/hypervisor.h>
+#include <asm/mshyperv.h>
+#include <asm/apic.h>
+
+#include <asm/trace/hyperv.h>
+
+static struct apic orig_apic;
+
+static u64 hv_apic_icr_read(void)
+{
+	u64 reg_val;
+
+	rdmsrl(HV_X64_MSR_ICR, reg_val);
+	return reg_val;
+}
+
+static void hv_apic_icr_write(u32 low, u32 id)
+{
+	u64 reg_val;
+
+	reg_val = SET_XAPIC_DEST_FIELD(id);
+	reg_val = reg_val << 32;
+	reg_val |= low;
+
+	wrmsrl(HV_X64_MSR_ICR, reg_val);
+}
+
+static u32 hv_apic_read(u32 reg)
+{
+	u32 reg_val, hi;
+
+	switch (reg) {
+	case APIC_EOI:
+		rdmsr(HV_X64_MSR_EOI, reg_val, hi);
+		(void)hi;
+		return reg_val;
+	case APIC_TASKPRI:
+		rdmsr(HV_X64_MSR_TPR, reg_val, hi);
+		(void)hi;
+		return reg_val;
+
+	default:
+		return native_apic_mem_read(reg);
+	}
+}
+
+static void hv_apic_write(u32 reg, u32 val)
+{
+	switch (reg) {
+	case APIC_EOI:
+		wrmsr(HV_X64_MSR_EOI, val, 0);
+		break;
+	case APIC_TASKPRI:
+		wrmsr(HV_X64_MSR_TPR, val, 0);
+		break;
+	default:
+		native_apic_mem_write(reg, val);
+	}
+}
+
+static void hv_apic_eoi_write(void)
+{
+	struct hv_vp_assist_page *hvp = hv_vp_assist_page[smp_processor_id()];
+
+	if (hvp && (xchg(&hvp->apic_assist, 0) & 0x1))
+		return;
+
+	wrmsr(HV_X64_MSR_EOI, APIC_EOI_ACK, 0);
+}
+
+static bool cpu_is_self(int cpu)
+{
+	return cpu == smp_processor_id();
+}
+
+/*
+ * IPI implementation on Hyper-V.
+ */
+static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector,
+		bool exclude_self)
+{
+	struct hv_send_ipi_ex *ipi_arg;
+	unsigned long flags;
+	int nr_bank = 0;
+	u64 status = HV_STATUS_INVALID_PARAMETER;
+
+	if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
+		return false;
+
+	local_irq_save(flags);
+	ipi_arg = *this_cpu_ptr(hyperv_pcpu_input_arg);
+
+	if (unlikely(!ipi_arg))
+		goto ipi_mask_ex_done;
+
+	ipi_arg->vector = vector;
+	ipi_arg->reserved = 0;
+	ipi_arg->vp_set.valid_bank_mask = 0;
+
+	/*
+	 * Use HV_GENERIC_SET_ALL and avoid converting cpumask to VP_SET
+	 * when the IPI is sent to all currently present CPUs.
+	 */
+	if (!cpumask_equal(mask, cpu_present_mask) || exclude_self) {
+		ipi_arg->vp_set.format = HV_GENERIC_SET_SPARSE_4K;
+
+		nr_bank = cpumask_to_vpset_skip(&(ipi_arg->vp_set), mask,
+				exclude_self ? cpu_is_self : NULL);
+
+		/*
+		 * 'nr_bank <= 0' means some CPUs in cpumask can't be
+		 * represented in VP_SET. Return an error and fall back to
+		 * native (architectural) method of sending IPIs.
+		 */
+		if (nr_bank <= 0)
+			goto ipi_mask_ex_done;
+	} else {
+		ipi_arg->vp_set.format = HV_GENERIC_SET_ALL;
+	}
+
+	status = hv_do_rep_hypercall(HVCALL_SEND_IPI_EX, 0, nr_bank,
+			      ipi_arg, NULL);
+
+ipi_mask_ex_done:
+	local_irq_restore(flags);
+	return hv_result_success(status);
+}
+
+static bool __send_ipi_mask(const struct cpumask *mask, int vector,
+		bool exclude_self)
+{
+	int cur_cpu, vcpu, this_cpu = smp_processor_id();
+	struct hv_send_ipi ipi_arg;
+	u64 status;
+	unsigned int weight;
+
+	trace_hyperv_send_ipi_mask(mask, vector);
+
+	weight = cpumask_weight(mask);
+
+	/*
+	 * Do nothing if
+	 *   1. the mask is empty
+	 *   2. the mask only contains self when exclude_self is true
+	 */
+	if (weight == 0 ||
+	    (exclude_self && weight == 1 && cpumask_test_cpu(this_cpu, mask)))
+		return true;
+
+	/* A fully enlightened TDX VM uses GHCI rather than hv_hypercall_pg. */
+	if (!hv_hypercall_pg) {
+		if (ms_hyperv.paravisor_present || !hv_isolation_type_tdx())
+			return false;
+	}
+
+	if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))
+		return false;
+
+	/*
+	 * From the supplied CPU set we need to figure out if we can get away
+	 * with cheaper HVCALL_SEND_IPI hypercall. This is possible when the
+	 * highest VP number in the set is < 64. As VP numbers are usually in
+	 * ascending order and match Linux CPU ids, here is an optimization:
+	 * we check the VP number for the highest bit in the supplied set first
+	 * so we can quickly find out if using HVCALL_SEND_IPI_EX hypercall is
+	 * a must. We will also check all VP numbers when walking the supplied
+	 * CPU set to remain correct in all cases.
+	 */
+	if (hv_cpu_number_to_vp_number(cpumask_last(mask)) >= 64)
+		goto do_ex_hypercall;
+
+	ipi_arg.vector = vector;
+	ipi_arg.cpu_mask = 0;
+
+	for_each_cpu(cur_cpu, mask) {
+		if (exclude_self && cur_cpu == this_cpu)
+			continue;
+		vcpu = hv_cpu_number_to_vp_number(cur_cpu);
+		if (vcpu == VP_INVAL)
+			return false;
+
+		/*
+		 * This particular version of the IPI hypercall can
+		 * only target upto 64 CPUs.
+		 */
+		if (vcpu >= 64)
+			goto do_ex_hypercall;
+
+		__set_bit(vcpu, (unsigned long *)&ipi_arg.cpu_mask);
+	}
+
+	status = hv_do_fast_hypercall16(HVCALL_SEND_IPI, ipi_arg.vector,
+				     ipi_arg.cpu_mask);
+	return hv_result_success(status);
+
+do_ex_hypercall:
+	return __send_ipi_mask_ex(mask, vector, exclude_self);
+}
+
+static bool __send_ipi_one(int cpu, int vector)
+{
+	int vp = hv_cpu_number_to_vp_number(cpu);
+	u64 status;
+
+	trace_hyperv_send_ipi_one(cpu, vector);
+
+	if (vp == VP_INVAL)
+		return false;
+
+	/* A fully enlightened TDX VM uses GHCI rather than hv_hypercall_pg. */
+	if (!hv_hypercall_pg) {
+		if (ms_hyperv.paravisor_present || !hv_isolation_type_tdx())
+			return false;
+	}
+
+	if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))
+		return false;
+
+	if (vp >= 64)
+		return __send_ipi_mask_ex(cpumask_of(cpu), vector, false);
+
+	status = hv_do_fast_hypercall16(HVCALL_SEND_IPI, vector, BIT_ULL(vp));
+	return hv_result_success(status);
+}
+
+static void hv_send_ipi(int cpu, int vector)
+{
+	if (!__send_ipi_one(cpu, vector))
+		orig_apic.send_IPI(cpu, vector);
+}
+
+static void hv_send_ipi_mask(const struct cpumask *mask, int vector)
+{
+	if (!__send_ipi_mask(mask, vector, false))
+		orig_apic.send_IPI_mask(mask, vector);
+}
+
+static void hv_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
+{
+	if (!__send_ipi_mask(mask, vector, true))
+		orig_apic.send_IPI_mask_allbutself(mask, vector);
+}
+
+static void hv_send_ipi_allbutself(int vector)
+{
+	hv_send_ipi_mask_allbutself(cpu_online_mask, vector);
+}
+
+static void hv_send_ipi_all(int vector)
+{
+	if (!__send_ipi_mask(cpu_online_mask, vector, false))
+		orig_apic.send_IPI_all(vector);
+}
+
+static void hv_send_ipi_self(int vector)
+{
+	if (!__send_ipi_one(smp_processor_id(), vector))
+		orig_apic.send_IPI_self(vector);
+}
+
+void __init hv_apic_init(void)
+{
+	if (ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) {
+		pr_info("Hyper-V: Using IPI hypercalls\n");
+		/*
+		 * Set the IPI entry points.
+		 */
+		orig_apic = *apic;
+
+		apic_update_callback(send_IPI, hv_send_ipi);
+		apic_update_callback(send_IPI_mask, hv_send_ipi_mask);
+		apic_update_callback(send_IPI_mask_allbutself, hv_send_ipi_mask_allbutself);
+		apic_update_callback(send_IPI_allbutself, hv_send_ipi_allbutself);
+		apic_update_callback(send_IPI_all, hv_send_ipi_all);
+		apic_update_callback(send_IPI_self, hv_send_ipi_self);
+	}
+
+	if (ms_hyperv.hints & HV_X64_APIC_ACCESS_RECOMMENDED) {
+		pr_info("Hyper-V: Using enlightened APIC (%s mode)",
+			x2apic_enabled() ? "x2apic" : "xapic");
+		/*
+		 * When in x2apic mode, don't use the Hyper-V specific APIC
+		 * accessors since the field layout in the ICR register is
+		 * different in x2apic mode. Furthermore, the architectural
+		 * x2apic MSRs function just as well as the Hyper-V
+		 * synthetic APIC MSRs, so there's no benefit in having
+		 * separate Hyper-V accessors for x2apic mode. The only
+		 * exception is hv_apic_eoi_write, because it benefits from
+		 * lazy EOI when available, but the same accessor works for
+		 * both xapic and x2apic because the field layout is the same.
+		 */
+		apic_update_callback(eoi, hv_apic_eoi_write);
+		if (!x2apic_enabled()) {
+			apic_update_callback(read, hv_apic_read);
+			apic_update_callback(write, hv_apic_write);
+			apic_update_callback(icr_write, hv_apic_icr_write);
+			apic_update_callback(icr_read, hv_apic_icr_read);
+		}
+	}
+}