Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 28b835d6 authored by Feng Wu's avatar Feng Wu Committed by Paolo Bonzini
Browse files

KVM: Update Posted-Interrupts Descriptor when vCPU is preempted 



This patch updates the Posted-Interrupts Descriptor when vCPU
is preempted.

sched out:
- Set 'SN' to suppress furture non-urgent interrupts posted for
the vCPU.

sched in:
- Clear 'SN'
- Change NDST if vCPU is scheduled to a different CPU
- Set 'NV' to POSTED_INTR_VECTOR

Signed-off-by: default avatarFeng Wu <feng.wu@intel.com>
[Include asm/cpu.h to fix !CONFIG_SMP compilation. - Paolo]
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 87276880

arch/x86/kvm/vmx.c

+80 −0
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ 
#include "kvm_cache_regs.h"

#include "x86.h"



#include <asm/cpu.h>

#include <asm/io.h>

#include <asm/desc.h>

#include <asm/vmx.h>
@@ -1942,6 +1943,52 @@ static void vmx_load_host_state(struct vcpu_vmx *vmx) 
	preempt_enable();

}



static void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)

{

	struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);

	struct pi_desc old, new;

	unsigned int dest;



	if (!kvm_arch_has_assigned_device(vcpu->kvm) ||

		!irq_remapping_cap(IRQ_POSTING_CAP))

		return;



	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);

}

/*

 * Switches to specified vcpu, until a matching vcpu_put(), but assumes

 * vcpu mutex is already taken.
@@ -1992,10 +2039,27 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) 
		vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */

		vmx->loaded_vmcs->cpu = cpu;

	}



	vmx_vcpu_pi_load(vcpu, cpu);

}



static void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu)

{

	struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);



	if (!kvm_arch_has_assigned_device(vcpu->kvm) ||

		!irq_remapping_cap(IRQ_POSTING_CAP))

		return;



	/* Set SN when the vCPU is preempted */

	if (vcpu->preempted)

		pi_set_sn(pi_desc);

}



static void vmx_vcpu_put(struct kvm_vcpu *vcpu)

{

	vmx_vcpu_pi_put(vcpu);



	__vmx_load_host_state(to_vmx(vcpu));

	if (!vmm_exclusive) {

		__loaded_vmcs_clear(to_vmx(vcpu)->loaded_vmcs);
@@ -4427,6 +4491,22 @@ static inline bool kvm_vcpu_trigger_posted_interrupt(struct kvm_vcpu *vcpu) 
{

#ifdef CONFIG_SMP

	if (vcpu->mode == IN_GUEST_MODE) {

		struct vcpu_vmx *vmx = to_vmx(vcpu);



		/*

		 * Currently, we don't support urgent interrupt,

		 * all interrupts are recognized as non-urgent

		 * interrupt, so we cannot post interrupts when

		 * 'SN' is set.

		 *

		 * If the vcpu is in guest mode, it means it is

		 * running instead of being scheduled out and

		 * waiting in the run queue, and that's the only

		 * case when 'SN' is set currently, warning if

		 * 'SN' is set.

		 */

		WARN_ON_ONCE(pi_test_sn(&vmx->pi_desc));



		apic->send_IPI_mask(get_cpu_mask(vcpu->cpu),

				POSTED_INTR_VECTOR);

		return true;