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KVM: Update Posted-Interrupts Descriptor when vCPU is preempted

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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: Feng Wu <feng.wu@intel.com>
[Include asm/cpu.h to fix !CONFIG_SMP compilation. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Feng Wu 2015-09-18 22:29:54 +08:00 committed by Paolo Bonzini
parent 8727688006
commit 28b835d60f
1 changed files with 80 additions and 0 deletions
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80
arch/x86/kvm/vmx.c
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@ -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;