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: Feng Wu <feng.wu@intel.com>
[Include asm/cpu.h to fix !CONFIG_SMP compilation. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index cb26b93..99f5c61 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -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 @@
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 @@
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 @@
{
#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;