linux-stable/arch/x86/hyperv/hv_apic.c
Vitaly Kuznetsov f5c20e4a5f x86/hyperv: Avoid erroneously sending IPI to 'self'
__send_ipi_mask_ex() uses an optimization: when the target CPU mask is
equal to 'cpu_present_mask' it uses 'HV_GENERIC_SET_ALL' format to avoid
converting the specified cpumask to VP_SET. This case was overlooked when
'exclude_self' parameter was added. As the result, a spurious IPI to
'self' can be send.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Fixes: dfb5c1e12c ("x86/hyperv: remove on-stack cpumask from hv_send_ipi_mask_allbutself")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20211006125016.941616-1-vkuznets@redhat.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-10-06 15:56:45 +00:00

317 lines
7.9 KiB
C

// 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_APIC_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(u32 reg, u32 val)
{
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, val, 0);
}
/*
* 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 **arg;
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);
arg = (struct hv_send_ipi_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
ipi_arg = *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;
if (exclude_self)
nr_bank = cpumask_to_vpset_noself(&(ipi_arg->vp_set), mask);
else
nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask);
/*
* '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;
if (!hv_hypercall_pg)
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 (!hv_hypercall_pg || (vp == VP_INVAL))
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->send_IPI = hv_send_ipi;
apic->send_IPI_mask = hv_send_ipi_mask;
apic->send_IPI_mask_allbutself = hv_send_ipi_mask_allbutself;
apic->send_IPI_allbutself = hv_send_ipi_allbutself;
apic->send_IPI_all = hv_send_ipi_all;
apic->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_set_eoi_write(hv_apic_eoi_write);
if (!x2apic_enabled()) {
apic->read = hv_apic_read;
apic->write = hv_apic_write;
apic->icr_write = hv_apic_icr_write;
apic->icr_read = hv_apic_icr_read;
}
}
}