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e211288b72
Now that there's Hyper-V IOMMU driver, Linux can switch to x2apic mode when supported by the vcpus. However, the apic access functions for Hyper-V enlightened apic assume xapic mode only. As a result, Linux fails to bring up secondary cpus when run as a guest in QEMU/KVM with both hv_apic and x2apic enabled. According to Michael Kelley, when in x2apic mode, the Hyper-V synthetic apic MSRs behave exactly the same as the corresponding architectural x2apic MSRs, so there's no need to override the apic accessors. The only exception is hv_apic_eoi_write, which benefits from lazy EOI when available; however, its implementation works for both xapic and x2apic modes. Fixes:29217a4746
("iommu/hyper-v: Add Hyper-V stub IOMMU driver") Fixes:6b48cb5f83
("X86/Hyper-V: Enlighten APIC access") Suggested-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Roman Kagan <rkagan@virtuozzo.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20191010123258.16919-1-rkagan@virtuozzo.com
281 lines
6.7 KiB
C
281 lines
6.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Hyper-V specific APIC code.
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*
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* Copyright (C) 2018, Microsoft, Inc.
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*
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* Author : K. Y. Srinivasan <kys@microsoft.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published
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* by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for more
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* details.
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*
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*/
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#include <linux/types.h>
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#include <linux/vmalloc.h>
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#include <linux/mm.h>
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#include <linux/clockchips.h>
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#include <linux/hyperv.h>
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#include <linux/slab.h>
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#include <linux/cpuhotplug.h>
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#include <asm/hypervisor.h>
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#include <asm/mshyperv.h>
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#include <asm/apic.h>
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#include <asm/trace/hyperv.h>
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static struct apic orig_apic;
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static u64 hv_apic_icr_read(void)
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{
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u64 reg_val;
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rdmsrl(HV_X64_MSR_ICR, reg_val);
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return reg_val;
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}
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static void hv_apic_icr_write(u32 low, u32 id)
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{
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u64 reg_val;
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reg_val = SET_APIC_DEST_FIELD(id);
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reg_val = reg_val << 32;
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reg_val |= low;
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wrmsrl(HV_X64_MSR_ICR, reg_val);
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}
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static u32 hv_apic_read(u32 reg)
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{
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u32 reg_val, hi;
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switch (reg) {
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case APIC_EOI:
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rdmsr(HV_X64_MSR_EOI, reg_val, hi);
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return reg_val;
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case APIC_TASKPRI:
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rdmsr(HV_X64_MSR_TPR, reg_val, hi);
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return reg_val;
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default:
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return native_apic_mem_read(reg);
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}
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}
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static void hv_apic_write(u32 reg, u32 val)
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{
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switch (reg) {
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case APIC_EOI:
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wrmsr(HV_X64_MSR_EOI, val, 0);
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break;
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case APIC_TASKPRI:
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wrmsr(HV_X64_MSR_TPR, val, 0);
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break;
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default:
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native_apic_mem_write(reg, val);
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}
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}
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static void hv_apic_eoi_write(u32 reg, u32 val)
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{
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struct hv_vp_assist_page *hvp = hv_vp_assist_page[smp_processor_id()];
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if (hvp && (xchg(&hvp->apic_assist, 0) & 0x1))
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return;
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wrmsr(HV_X64_MSR_EOI, val, 0);
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}
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/*
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* IPI implementation on Hyper-V.
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*/
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static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector)
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{
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struct hv_send_ipi_ex **arg;
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struct hv_send_ipi_ex *ipi_arg;
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unsigned long flags;
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int nr_bank = 0;
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int ret = 1;
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if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
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return false;
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local_irq_save(flags);
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arg = (struct hv_send_ipi_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
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ipi_arg = *arg;
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if (unlikely(!ipi_arg))
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goto ipi_mask_ex_done;
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ipi_arg->vector = vector;
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ipi_arg->reserved = 0;
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ipi_arg->vp_set.valid_bank_mask = 0;
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if (!cpumask_equal(mask, cpu_present_mask)) {
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ipi_arg->vp_set.format = HV_GENERIC_SET_SPARSE_4K;
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nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask);
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}
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if (nr_bank < 0)
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goto ipi_mask_ex_done;
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if (!nr_bank)
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ipi_arg->vp_set.format = HV_GENERIC_SET_ALL;
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ret = hv_do_rep_hypercall(HVCALL_SEND_IPI_EX, 0, nr_bank,
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ipi_arg, NULL);
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ipi_mask_ex_done:
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local_irq_restore(flags);
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return ((ret == 0) ? true : false);
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}
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static bool __send_ipi_mask(const struct cpumask *mask, int vector)
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{
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int cur_cpu, vcpu;
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struct hv_send_ipi ipi_arg;
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int ret = 1;
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trace_hyperv_send_ipi_mask(mask, vector);
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if (cpumask_empty(mask))
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return true;
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if (!hv_hypercall_pg)
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return false;
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if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))
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return false;
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/*
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* From the supplied CPU set we need to figure out if we can get away
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* with cheaper HVCALL_SEND_IPI hypercall. This is possible when the
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* highest VP number in the set is < 64. As VP numbers are usually in
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* ascending order and match Linux CPU ids, here is an optimization:
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* we check the VP number for the highest bit in the supplied set first
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* so we can quickly find out if using HVCALL_SEND_IPI_EX hypercall is
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* a must. We will also check all VP numbers when walking the supplied
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* CPU set to remain correct in all cases.
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*/
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if (hv_cpu_number_to_vp_number(cpumask_last(mask)) >= 64)
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goto do_ex_hypercall;
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ipi_arg.vector = vector;
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ipi_arg.cpu_mask = 0;
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for_each_cpu(cur_cpu, mask) {
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vcpu = hv_cpu_number_to_vp_number(cur_cpu);
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if (vcpu == VP_INVAL)
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return false;
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/*
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* This particular version of the IPI hypercall can
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* only target upto 64 CPUs.
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*/
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if (vcpu >= 64)
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goto do_ex_hypercall;
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__set_bit(vcpu, (unsigned long *)&ipi_arg.cpu_mask);
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}
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ret = hv_do_fast_hypercall16(HVCALL_SEND_IPI, ipi_arg.vector,
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ipi_arg.cpu_mask);
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return ((ret == 0) ? true : false);
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do_ex_hypercall:
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return __send_ipi_mask_ex(mask, vector);
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}
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static bool __send_ipi_one(int cpu, int vector)
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{
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struct cpumask mask = CPU_MASK_NONE;
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cpumask_set_cpu(cpu, &mask);
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return __send_ipi_mask(&mask, vector);
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}
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static void hv_send_ipi(int cpu, int vector)
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{
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if (!__send_ipi_one(cpu, vector))
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orig_apic.send_IPI(cpu, vector);
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}
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static void hv_send_ipi_mask(const struct cpumask *mask, int vector)
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{
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if (!__send_ipi_mask(mask, vector))
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orig_apic.send_IPI_mask(mask, vector);
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}
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static void hv_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
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{
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unsigned int this_cpu = smp_processor_id();
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struct cpumask new_mask;
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const struct cpumask *local_mask;
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cpumask_copy(&new_mask, mask);
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cpumask_clear_cpu(this_cpu, &new_mask);
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local_mask = &new_mask;
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if (!__send_ipi_mask(local_mask, vector))
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orig_apic.send_IPI_mask_allbutself(mask, vector);
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}
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static void hv_send_ipi_allbutself(int vector)
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{
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hv_send_ipi_mask_allbutself(cpu_online_mask, vector);
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}
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static void hv_send_ipi_all(int vector)
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{
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if (!__send_ipi_mask(cpu_online_mask, vector))
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orig_apic.send_IPI_all(vector);
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}
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static void hv_send_ipi_self(int vector)
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{
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if (!__send_ipi_one(smp_processor_id(), vector))
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orig_apic.send_IPI_self(vector);
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}
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void __init hv_apic_init(void)
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{
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if (ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) {
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pr_info("Hyper-V: Using IPI hypercalls\n");
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/*
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* Set the IPI entry points.
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*/
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orig_apic = *apic;
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apic->send_IPI = hv_send_ipi;
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apic->send_IPI_mask = hv_send_ipi_mask;
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apic->send_IPI_mask_allbutself = hv_send_ipi_mask_allbutself;
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apic->send_IPI_allbutself = hv_send_ipi_allbutself;
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apic->send_IPI_all = hv_send_ipi_all;
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apic->send_IPI_self = hv_send_ipi_self;
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}
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if (ms_hyperv.hints & HV_X64_APIC_ACCESS_RECOMMENDED) {
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pr_info("Hyper-V: Using enlightened APIC (%s mode)",
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x2apic_enabled() ? "x2apic" : "xapic");
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/*
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* With x2apic, architectural x2apic MSRs are equivalent to the
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* respective synthetic MSRs, so there's no need to override
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* the apic accessors. The only exception is
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* hv_apic_eoi_write, because it benefits from lazy EOI when
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* available, but it works for both xapic and x2apic modes.
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*/
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apic_set_eoi_write(hv_apic_eoi_write);
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if (!x2apic_enabled()) {
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apic->read = hv_apic_read;
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apic->write = hv_apic_write;
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apic->icr_write = hv_apic_icr_write;
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apic->icr_read = hv_apic_icr_read;
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}
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}
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}
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