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KVM: VMX: Move Posted Interrupt ndst computation out of write loop

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Hoist the CPU => APIC ID conversion for the Posted Interrupt descriptor
out of the loop to write the descriptor, preemption is disabled so the
CPU won't change, and if the APIC ID changes KVM has bigger problems.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-28-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-10-08 19:12:20 -07:00 committed by Paolo Bonzini
parent cfb0e1306a
commit 724b3962ef
1 changed files with 11 additions and 14 deletions
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25
arch/x86/kvm/vmx/posted_intr.c
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@ -52,17 +52,15 @@ void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)
goto after_clear_sn;
}
/* The full case. */
/* The full case. Set the new destination and clear SN. */
dest = cpu_physical_id(cpu);
if (!x2apic_mode)
dest = (dest << 8) & 0xFF00;
do {
old.control = new.control = READ_ONCE(pi_desc->control);
dest = cpu_physical_id(cpu);
if (x2apic_mode)
new.ndst = dest;
else
new.ndst = (dest << 8) & 0xFF00;
new.ndst = dest;
new.sn = 0;
} while (cmpxchg64(&pi_desc->control, old.control,
new.control) != old.control);
@ -106,17 +104,16 @@ static void __pi_post_block(struct kvm_vcpu *vcpu)
struct pi_desc old, new;
unsigned int dest;
dest = cpu_physical_id(vcpu->cpu);
if (!x2apic_mode)
dest = (dest << 8) & 0xFF00;
do {
old.control = new.control = READ_ONCE(pi_desc->control);
WARN(old.nv != POSTED_INTR_WAKEUP_VECTOR,
"Wakeup handler not enabled while the VCPU is blocked\n");
dest = cpu_physical_id(vcpu->cpu);
if (x2apic_mode)
new.ndst = dest;
else
new.ndst = (dest << 8) & 0xFF00;
new.ndst = dest;
/* set 'NV' to 'notification vector' */
new.nv = POSTED_INTR_VECTOR;