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

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

arch/x86/kvm/vmx.c

+35 −33
Original line number Diff line number Diff line
@@ -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,