From 28b835d60fcc2498e717cf5e6f0c3691c24546f7 Mon Sep 17 00:00:00 2001 From: Feng Wu Date: Fri, 18 Sep 2015 22:29:54 +0800 Subject: [PATCH] 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 [Include asm/cpu.h to fix !CONFIG_SMP compilation. - Paolo] Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 80 insertions(+) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index cb26b93a2cd7..99f5c61954ea 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 #include #include #include @@ -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; -- 2.20.1