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KVM: VMX: Drop unnecessary PI logic to handle impossible conditions

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Drop sanity checks on the validity of the previous pCPU when handling
vCPU block/unlock for posted interrupts.  The intention behind the sanity
checks is to avoid memory corruption in case of a race or incorrect locking,
but the code has been stable for a few years now and the checks get in
the way of eliminating kvm_vcpu.pre_cpu.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-23-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-10-08 19:12:15 -07:00 committed by Paolo Bonzini
parent 057aa61bc9
commit c95717218a
1 changed files with 10 additions and 14 deletions
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24
arch/x86/kvm/vmx/posted_intr.c
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@ -123,12 +123,10 @@ static void __pi_post_block(struct kvm_vcpu *vcpu)
} while (cmpxchg64(&pi_desc->control, old.control,
new.control) != old.control);
if (!WARN_ON_ONCE(vcpu->pre_pcpu == -1)) {
spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
list_del(&vcpu->blocked_vcpu_list);
spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
vcpu->pre_pcpu = -1;
}
spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
list_del(&vcpu->blocked_vcpu_list);
spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
vcpu->pre_pcpu = -1;
}
/*
@ -156,14 +154,12 @@ int pi_pre_block(struct kvm_vcpu *vcpu)
WARN_ON(irqs_disabled());
local_irq_disable();
if (!WARN_ON_ONCE(vcpu->pre_pcpu != -1)) {
vcpu->pre_pcpu = vcpu->cpu;
spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
list_add_tail(&vcpu->blocked_vcpu_list,
&per_cpu(blocked_vcpu_on_cpu,
vcpu->pre_pcpu));
spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
}
vcpu->pre_pcpu = vcpu->cpu;
spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
list_add_tail(&vcpu->blocked_vcpu_list,
&per_cpu(blocked_vcpu_on_cpu, vcpu->pre_pcpu));
spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
do {
old.control = new.control = pi_desc->control;