This patch updates the Posted-Interrupts Descriptor when vCPU is blocked. pre-block: - Add the vCPU to the blocked per-CPU list - Set 'NV' to POSTED_INTR_WAKEUP_VECTOR
post-block: - Remove the vCPU from the per-CPU list Signed-off-by: Feng Wu <feng...@intel.com> --- arch/x86/include/asm/kvm_host.h | 3 + arch/x86/kvm/vmx.c | 158 ++++++++++++++++++++++++++++++++++++++++ arch/x86/kvm/x86.c | 42 ++++++++--- include/linux/kvm_host.h | 3 + virt/kvm/kvm_main.c | 3 + 5 files changed, 199 insertions(+), 10 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 1605bf8..2ef6f2a 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -842,6 +842,9 @@ struct kvm_x86_ops { void (*pi_clear_sn)(struct kvm_vcpu *vcpu); void (*pi_set_sn)(struct kvm_vcpu *vcpu); + + int (*pi_pre_block)(struct kvm_vcpu *vcpu); + void (*pi_post_block)(struct kvm_vcpu *vcpu); }; struct kvm_arch_async_pf { diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 9d9b403..7e8a800 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -888,6 +888,13 @@ static DEFINE_PER_CPU(struct vmcs *, current_vmcs); static DEFINE_PER_CPU(struct list_head, loaded_vmcss_on_cpu); static DEFINE_PER_CPU(struct desc_ptr, host_gdt); +/* + * We maintian a per-CPU linked-list of vCPU, so in wakeup_handler() we + * can find which vCPU should be waken up. + */ +static DEFINE_PER_CPU(struct list_head, blocked_vcpu_on_cpu); +static DEFINE_PER_CPU(spinlock_t, blocked_vcpu_on_cpu_lock); + static unsigned long *vmx_io_bitmap_a; static unsigned long *vmx_io_bitmap_b; static unsigned long *vmx_msr_bitmap_legacy; @@ -2972,6 +2979,8 @@ static int hardware_enable(void) return -EBUSY; INIT_LIST_HEAD(&per_cpu(loaded_vmcss_on_cpu, cpu)); + INIT_LIST_HEAD(&per_cpu(blocked_vcpu_on_cpu, cpu)); + spin_lock_init(&per_cpu(blocked_vcpu_on_cpu_lock, cpu)); /* * Now we can enable the vmclear operation in kdump @@ -6099,6 +6108,25 @@ static void update_ple_window_actual_max(void) ple_window_grow, INT_MIN); } +/* + * Handler for POSTED_INTERRUPT_WAKEUP_VECTOR. + */ +static void wakeup_handler(void) +{ + struct kvm_vcpu *vcpu; + int cpu = smp_processor_id(); + + spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, cpu)); + list_for_each_entry(vcpu, &per_cpu(blocked_vcpu_on_cpu, cpu), + blocked_vcpu_list) { + struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu); + + if (pi_test_on(pi_desc) == 1) + kvm_vcpu_kick(vcpu); + } + spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, cpu)); +} + static __init int hardware_setup(void) { int r = -ENOMEM, i, msr; @@ -6283,6 +6311,8 @@ static __init int hardware_setup(void) kvm_x86_ops->enable_log_dirty_pt_masked = NULL; } + kvm_set_posted_intr_wakeup_handler(wakeup_handler); + return alloc_kvm_area(); out8: @@ -10236,6 +10266,131 @@ static void vmx_enable_log_dirty_pt_masked(struct kvm *kvm, kvm_mmu_clear_dirty_pt_masked(kvm, memslot, offset, mask); } +/* + * This routine does the following things for vCPU which is going + * to be blocked if VT-d PI is enabled. + * - Store the vCPU to the wakeup list, so when interrupts happen + * we can find the right vCPU to wake up. + * - Change the Posted-interrupt descriptor as below: + * 'NDST' <-- vcpu->pre_pcpu + * 'NV' <-- POSTED_INTR_WAKEUP_VECTOR + * - If 'ON' is set during this process, which means at least one + * interrupt is posted for this vCPU, we cannot block it, in + * this case, return 1, otherwise, return 0. + * + */ +static int vmx_pi_pre_block(struct kvm_vcpu *vcpu) +{ + unsigned long flags; + unsigned int dest; + struct pi_desc old, new; + struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu); + + if (!irq_remapping_cap(IRQ_POSTING_CAP)) + return 0; + + vcpu->pre_pcpu = vcpu->cpu; + spin_lock_irqsave(&per_cpu(blocked_vcpu_on_cpu_lock, + vcpu->pre_pcpu), flags); + list_add_tail(&vcpu->blocked_vcpu_list, + &per_cpu(blocked_vcpu_on_cpu, + vcpu->pre_pcpu)); + spin_unlock_irqrestore(&per_cpu(blocked_vcpu_on_cpu_lock, + vcpu->pre_pcpu), flags); + + do { + old.control = new.control = pi_desc->control; + + /* + * We should not block the vCPU if + * an interrupt is posted for it. + */ + if (pi_test_on(pi_desc) == 1) { + spin_lock_irqsave(&per_cpu(blocked_vcpu_on_cpu_lock, + vcpu->pre_pcpu), flags); + list_del(&vcpu->blocked_vcpu_list); + spin_unlock_irqrestore( + &per_cpu(blocked_vcpu_on_cpu_lock, + vcpu->pre_pcpu), flags); + vcpu->pre_pcpu = -1; + + return 1; + } + + WARN((pi_desc->sn == 1), + "Warning: SN field of posted-interrupts " + "is set before blocking\n"); + + /* + * Since vCPU can be preempted during this process, + * vcpu->cpu could be different with pre_pcpu, we + * need to set pre_pcpu as the destination of wakeup + * notification event, then we can find the right vCPU + * to wakeup in wakeup handler if interrupts happen + * when the vCPU is in blocked state. + */ + dest = cpu_physical_id(vcpu->pre_pcpu); + + if (x2apic_enabled()) + new.ndst = dest; + else + new.ndst = (dest << 8) & 0xFF00; + + /* set 'NV' to 'wakeup vector' */ + new.nv = POSTED_INTR_WAKEUP_VECTOR; + } while (cmpxchg(&pi_desc->control, old.control, + new.control) != old.control); + + return 0; +} + +static void vmx_pi_post_block(struct kvm_vcpu *vcpu) +{ + struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu); + struct pi_desc old, new; + unsigned int dest; + unsigned long flags; + + if (!irq_remapping_cap(IRQ_POSTING_CAP)) + return; + + /* + * If the vCPU is not really blocked and vmx_vcpu_load() + * doesn't have chance to run before this point, we should + * set posted-interrupt descriptor back, just like what we + * do in vmx_vcpu_load(). + */ + if (pi_desc->nv == POSTED_INTR_WAKEUP_VECTOR) + do { + old.control = new.control = pi_desc->control; + + dest = cpu_physical_id(vcpu->cpu); + + if (x2apic_enabled()) + new.ndst = dest; + 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, + new.control) != old.control); + + if(vcpu->pre_pcpu != -1) { + spin_lock_irqsave( + &per_cpu(blocked_vcpu_on_cpu_lock, + vcpu->pre_pcpu), flags); + list_del(&vcpu->blocked_vcpu_list); + spin_unlock_irqrestore( + &per_cpu(blocked_vcpu_on_cpu_lock, + vcpu->pre_pcpu), flags); + vcpu->pre_pcpu = -1; + } +} + static struct kvm_x86_ops vmx_x86_ops = { .cpu_has_kvm_support = cpu_has_kvm_support, .disabled_by_bios = vmx_disabled_by_bios, @@ -10354,6 +10509,9 @@ static struct kvm_x86_ops vmx_x86_ops = { .pi_clear_sn = vmx_pi_clear_sn, .pi_set_sn = vmx_pi_set_sn, + + .pi_pre_block = vmx_pi_pre_block, + .pi_post_block = vmx_pi_post_block, }; static int __init vmx_init(void) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c73efcd..fabf4a7 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5866,7 +5866,11 @@ int kvm_vcpu_halt(struct kvm_vcpu *vcpu) { ++vcpu->stat.halt_exits; if (irqchip_in_kernel(vcpu->kvm)) { - vcpu->arch.mp_state = KVM_MP_STATE_HALTED; + /* Handle posted-interrupt when vCPU is to be halted */ + if (!kvm_x86_ops->pi_pre_block || + (kvm_x86_ops->pi_pre_block && + kvm_x86_ops->pi_pre_block(vcpu) == 0)) + vcpu->arch.mp_state = KVM_MP_STATE_HALTED; return 1; } else { vcpu->run->exit_reason = KVM_EXIT_HLT; @@ -6282,6 +6286,21 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) kvm_vcpu_reload_apic_access_page(vcpu); } + /* + * Since posted-interrupts can be set by VT-d HW now, in this + * case, KVM_REQ_EVENT is not set. We move the following + * operations out of the if statement. + */ + if (kvm_lapic_enabled(vcpu)) { + /* + * Update architecture specific hints for APIC + * virtual interrupt delivery. + */ + if (kvm_x86_ops->hwapic_irr_update) + kvm_x86_ops->hwapic_irr_update(vcpu, + kvm_lapic_find_highest_irr(vcpu)); + } + if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) { kvm_apic_accept_events(vcpu); if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) { @@ -6298,13 +6317,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) kvm_x86_ops->enable_irq_window(vcpu); if (kvm_lapic_enabled(vcpu)) { - /* - * Update architecture specific hints for APIC - * virtual interrupt delivery. - */ - if (kvm_x86_ops->hwapic_irr_update) - kvm_x86_ops->hwapic_irr_update(vcpu, - kvm_lapic_find_highest_irr(vcpu)); update_cr8_intercept(vcpu); kvm_lapic_sync_to_vapic(vcpu); } @@ -6475,10 +6487,20 @@ static int vcpu_run(struct kvm_vcpu *vcpu) for (;;) { if (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE && - !vcpu->arch.apf.halted) + !vcpu->arch.apf.halted) { r = vcpu_enter_guest(vcpu); - else + } else { r = vcpu_block(kvm, vcpu); + + /* + * pi_post_block() must be called after + * pi_pre_block() which is called in + * kvm_vcpu_halt(). + */ + if (kvm_x86_ops->pi_post_block) + kvm_x86_ops->pi_post_block(vcpu); + } + if (r <= 0) break; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 69f8711..6c90ef2 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -225,6 +225,9 @@ struct kvm_vcpu { unsigned long requests; unsigned long guest_debug; + int pre_pcpu; + struct list_head blocked_vcpu_list; + struct mutex mutex; struct kvm_run *run; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 9097741..6938554 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -221,6 +221,9 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id) init_waitqueue_head(&vcpu->wq); kvm_async_pf_vcpu_init(vcpu); + vcpu->pre_pcpu = -1; + INIT_LIST_HEAD(&vcpu->blocked_vcpu_list); + page = alloc_page(GFP_KERNEL | __GFP_ZERO); if (!page) { r = -ENOMEM; -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html