Commit 31afb2ea authored by Paolo Bonzini's avatar Paolo Bonzini

KVM: VMX: simplify and fix vmx_vcpu_pi_load

The simplify part: do not touch pi_desc.nv, we can set it when the
VCPU is first created.  Likewise, pi_desc.sn is only handled by
vmx_vcpu_pi_load, do not touch it in __pi_post_block.

The fix part: do not check kvm_arch_has_assigned_device, instead
check the SN bit to figure out whether vmx_vcpu_pi_put ran before.
This matches what the previous patch did in pi_post_block.

Cc: Huangweidong <weidong.huang@huawei.com>
Cc: Gonglei <arei.gonglei@huawei.com>
Cc: wangxin <wangxinxin.wang@huawei.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Tested-by: default avatarLongpeng (Mike) <longpeng2@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 8b306e2f
......@@ -2202,43 +2202,41 @@ static void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)
struct pi_desc old, new;
unsigned int dest;
if (!kvm_arch_has_assigned_device(vcpu->kvm) ||
!irq_remapping_cap(IRQ_POSTING_CAP) ||
!kvm_vcpu_apicv_active(vcpu))
/*
* In case of hot-plug or hot-unplug, we may have to undo
* vmx_vcpu_pi_put even if there is no assigned device. And we
* always keep PI.NDST up to date for simplicity: it makes the
* code easier, and CPU migration is not a fast path.
*/
if (!pi_test_sn(pi_desc) && vcpu->cpu == cpu)
return;
/*
* First handle the simple case where no cmpxchg is necessary; just
* allow posting non-urgent interrupts.
*
* If the 'nv' field is POSTED_INTR_WAKEUP_VECTOR, do not change
* PI.NDST: pi_post_block will do it for us and the wakeup_handler
* expects the VCPU to be on the blocked_vcpu_list that matches
* PI.NDST.
*/
if (pi_desc->nv == POSTED_INTR_WAKEUP_VECTOR ||
vcpu->cpu == cpu) {
pi_clear_sn(pi_desc);
return;
}
/* The full case. */
do {
old.control = new.control = pi_desc->control;
/*
* If 'nv' field is POSTED_INTR_WAKEUP_VECTOR, there
* are two possible cases:
* 1. After running 'pre_block', context switch
* happened. For this case, 'sn' was set in
* vmx_vcpu_put(), so we need to clear it here.
* 2. After running 'pre_block', we were blocked,
* and woken up by some other guy. For this case,
* we don't need to do anything, 'pi_post_block'
* will do everything for us. However, we cannot
* check whether it is case #1 or case #2 here
* (maybe, not needed), so we also clear sn here,
* I think it is not a big deal.
*/
if (pi_desc->nv != POSTED_INTR_WAKEUP_VECTOR) {
if (vcpu->cpu != cpu) {
dest = cpu_physical_id(cpu);
if (x2apic_enabled())
new.ndst = dest;
else
new.ndst = (dest << 8) & 0xFF00;
}
/* set 'NV' to 'notification vector' */
new.nv = POSTED_INTR_VECTOR;
}
/* Allow posting non-urgent interrupts */
new.sn = 0;
} while (cmpxchg(&pi_desc->control, old.control,
new.control) != old.control);
......@@ -9592,6 +9590,13 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
vmx->msr_ia32_feature_control_valid_bits = FEATURE_CONTROL_LOCKED;
/*
* Enforce invariant: pi_desc.nv is always either POSTED_INTR_VECTOR
* or POSTED_INTR_WAKEUP_VECTOR.
*/
vmx->pi_desc.nv = POSTED_INTR_VECTOR;
vmx->pi_desc.sn = 1;
return &vmx->vcpu;
free_vmcs:
......@@ -11723,9 +11728,6 @@ static void __pi_post_block(struct kvm_vcpu *vcpu)
else
new.ndst = (dest << 8) & 0xFF00;
/* Allow posting non-urgent interrupts */
new.sn = 0;
/* set 'NV' to 'notification vector' */
new.nv = POSTED_INTR_VECTOR;
} while (cmpxchg(&pi_desc->control, old.control,
......
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