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e840f42a49
Russell reported that since 5.13, KVM's probing of the PMU has
started to fail on his HW. As it turns out, there is an implicit
ordering dependency between the architectural PMU probing code and
and KVM's own probing. If, due to probe ordering reasons, KVM probes
before the PMU driver, it will fail to detect the PMU and prevent it
from being advertised to guests as well as the VMM.
Obviously, this is one probing too many, and we should be able to
deal with any ordering.
Add a callback from the PMU code into KVM to advertise the registration
of a host CPU PMU, allowing for any probing order.
Fixes: 5421db1be3 ("KVM: arm64: Divorce the perf code from oprofile helpers")
Reported-by: "Russell King (Oracle)" <linux@armlinux.org.uk>
Tested-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/YUYRKVflRtUytzy5@shell.armlinux.org.uk
Cc: stable@vger.kernel.org
59 lines
1 KiB
C
59 lines
1 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Based on the x86 implementation.
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*
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* Copyright (C) 2012 ARM Ltd.
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* Author: Marc Zyngier <marc.zyngier@arm.com>
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*/
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#include <linux/perf_event.h>
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#include <linux/kvm_host.h>
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#include <asm/kvm_emulate.h>
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DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
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static int kvm_is_in_guest(void)
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{
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return kvm_get_running_vcpu() != NULL;
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}
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static int kvm_is_user_mode(void)
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{
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struct kvm_vcpu *vcpu;
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vcpu = kvm_get_running_vcpu();
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if (vcpu)
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return !vcpu_mode_priv(vcpu);
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return 0;
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}
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static unsigned long kvm_get_guest_ip(void)
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{
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struct kvm_vcpu *vcpu;
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vcpu = kvm_get_running_vcpu();
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if (vcpu)
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return *vcpu_pc(vcpu);
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return 0;
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}
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static struct perf_guest_info_callbacks kvm_guest_cbs = {
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.is_in_guest = kvm_is_in_guest,
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.is_user_mode = kvm_is_user_mode,
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.get_guest_ip = kvm_get_guest_ip,
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};
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int kvm_perf_init(void)
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{
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return perf_register_guest_info_callbacks(&kvm_guest_cbs);
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}
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int kvm_perf_teardown(void)
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{
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return perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
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}
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