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Date: Fri, 11 Sep 2015 13:21:22 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Feng Wu <feng.wu@...el.com>, alex.williamson@...hat.com,
joro@...tes.org, mtosatti@...hat.com
Cc: eric.auger@...aro.org, kvm@...r.kernel.org,
iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 15/17] KVM: Update Posted-Interrupts Descriptor when
vCPU is blocked
On 25/08/2015 10:50, Feng Wu wrote:
> 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.wu@...el.com>
> ---
> arch/x86/include/asm/kvm_host.h | 5 ++
> arch/x86/kvm/vmx.c | 151 ++++++++++++++++++++++++++++++++++++++++
> arch/x86/kvm/x86.c | 55 ++++++++++++---
> include/linux/kvm_host.h | 3 +
> virt/kvm/kvm_main.c | 3 +
> 5 files changed, 207 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 22269b4..32af275 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -554,6 +554,8 @@ struct kvm_vcpu_arch {
> */
> bool write_fault_to_shadow_pgtable;
>
> + bool halted;
> +
> /* set at EPT violation at this point */
> unsigned long exit_qualification;
>
> @@ -868,6 +870,9 @@ 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);
Just pre_block/post_block please. Also, please document the return
value of pre_block.
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index ef93fdc..fc7f222 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5869,7 +5869,13 @@ 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 &&
No need to test kvm_x86_ops->pi_pre_block again.
> + kvm_x86_ops->pi_pre_block(vcpu) == 0)) {
> + vcpu->arch.halted = true;
> + vcpu->arch.mp_state = KVM_MP_STATE_HALTED;
> + }
> return 1;
> } else {
> vcpu->run->exit_reason = KVM_EXIT_HLT;
> @@ -6518,6 +6524,21 @@ 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.
> + */
Just "KVM_REQ_EVENT is not set when posted interrupts are set by VT-d
hardware, so we have to update RVI unconditionally", please.
Could we skip this (in a future patch) if PI.ON=0?
> + 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) {
> @@ -6534,13 +6555,6 @@ 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);
> }
> @@ -6711,10 +6725,31 @@ 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) {
> + /*
> + * For some cases, we can get here with
> + * vcpu->arch.halted being true.
> + */
Which cases?
Paolo
> + if (kvm_x86_ops->pi_post_block && vcpu->arch.halted) {
> + kvm_x86_ops->pi_post_block(vcpu);
> + vcpu->arch.halted = false;
> + }
> +
> 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 && vcpu->arch.halted) {
> + kvm_x86_ops->pi_post_block(vcpu);
> + vcpu->arch.halted = false;
> + }
> + }
> +
> if (r <= 0)
> break;
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index f4005dc..6aa69f4 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -233,6 +233,9 @@ 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 8b8a444..191c7eb 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -220,6 +220,9 @@ 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;
>
--
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