From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754788AbaIBQAm (ORCPT ); Tue, 2 Sep 2014 12:00:42 -0400 Received: from mail-wi0-f182.google.com ([209.85.212.182]:43354 "EHLO mail-wi0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754651AbaIBQAK (ORCPT ); Tue, 2 Sep 2014 12:00:10 -0400 Date: Tue, 2 Sep 2014 19:00:05 +0300 From: Gleb Natapov To: Tang Chen Cc: mtosatti@redhat.com, nadav.amit@gmail.com, jan.kiszka@web.de, kvm@vger.kernel.org, laijs@cn.fujitsu.com, isimatu.yasuaki@jp.fujitsu.com, guz.fnst@cn.fujitsu.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 4/6] kvm, mem-hotplug: Reload L1' apic access page on migration in vcpu_enter_guest(). Message-ID: <20140902160005.GA26540@minantech.com> References: <1409134661-27916-1-git-send-email-tangchen@cn.fujitsu.com> <1409134661-27916-5-git-send-email-tangchen@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1409134661-27916-5-git-send-email-tangchen@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 27, 2014 at 06:17:39PM +0800, Tang Chen wrote: > apic access page is pinned in memory. As a result, it cannot be migrated/hot-removed. > Actually, it is not necessary to be pinned. > > The hpa of apic access page is stored in VMCS APIC_ACCESS_ADDR pointer. When > the page is migrated, kvm_mmu_notifier_invalidate_page() will invalidate the > corresponding ept entry. This patch introduces a new vcpu request named > KVM_REQ_APIC_PAGE_RELOAD, and makes this request to all the vcpus at this time, > and force all the vcpus exit guest, and re-enter guest till they updates the VMCS > APIC_ACCESS_ADDR pointer to the new apic access page address, and updates > kvm->arch.apic_access_page to the new page. > > Signed-off-by: Tang Chen > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/svm.c | 6 ++++++ > arch/x86/kvm/vmx.c | 6 ++++++ > arch/x86/kvm/x86.c | 15 +++++++++++++++ > include/linux/kvm_host.h | 2 ++ > virt/kvm/kvm_main.c | 12 ++++++++++++ > 6 files changed, 42 insertions(+) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 35171c7..514183e 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -739,6 +739,7 @@ struct kvm_x86_ops { > void (*hwapic_isr_update)(struct kvm *kvm, int isr); > void (*load_eoi_exitmap)(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap); > void (*set_virtual_x2apic_mode)(struct kvm_vcpu *vcpu, bool set); > + void (*set_apic_access_page_addr)(struct kvm *kvm, hpa_t hpa); > void (*deliver_posted_interrupt)(struct kvm_vcpu *vcpu, int vector); > void (*sync_pir_to_irr)(struct kvm_vcpu *vcpu); > int (*set_tss_addr)(struct kvm *kvm, unsigned int addr); > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 1d941ad..f2eacc4 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -3619,6 +3619,11 @@ static void svm_set_virtual_x2apic_mode(struct kvm_vcpu *vcpu, bool set) > return; > } > > +static void svm_set_apic_access_page_addr(struct kvm *kvm, hpa_t hpa) > +{ > + return; > +} > + > static int svm_vm_has_apicv(struct kvm *kvm) > { > return 0; > @@ -4373,6 +4378,7 @@ static struct kvm_x86_ops svm_x86_ops = { > .enable_irq_window = enable_irq_window, > .update_cr8_intercept = update_cr8_intercept, > .set_virtual_x2apic_mode = svm_set_virtual_x2apic_mode, > + .set_apic_access_page_addr = svm_set_apic_access_page_addr, > .vm_has_apicv = svm_vm_has_apicv, > .load_eoi_exitmap = svm_load_eoi_exitmap, > .hwapic_isr_update = svm_hwapic_isr_update, > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 63c4c3e..da6d55d 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -7093,6 +7093,11 @@ static void vmx_set_virtual_x2apic_mode(struct kvm_vcpu *vcpu, bool set) > vmx_set_msr_bitmap(vcpu); > } > > +static void vmx_set_apic_access_page_addr(struct kvm *kvm, hpa_t hpa) > +{ > + vmcs_write64(APIC_ACCESS_ADDR, hpa); > +} > + > static void vmx_hwapic_isr_update(struct kvm *kvm, int isr) > { > u16 status; > @@ -8910,6 +8915,7 @@ static struct kvm_x86_ops vmx_x86_ops = { > .enable_irq_window = enable_irq_window, > .update_cr8_intercept = update_cr8_intercept, > .set_virtual_x2apic_mode = vmx_set_virtual_x2apic_mode, > + .set_apic_access_page_addr = vmx_set_apic_access_page_addr, > .vm_has_apicv = vmx_vm_has_apicv, > .load_eoi_exitmap = vmx_load_eoi_exitmap, > .hwapic_irr_update = vmx_hwapic_irr_update, > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index e05bd58..96f4188 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -5989,6 +5989,19 @@ static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu) > kvm_apic_update_tmr(vcpu, tmr); > } > > +static void vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu) > +{ > + /* > + * apic access page could be migrated. When the page is being migrated, > + * GUP will wait till the migrate entry is replaced with the new pte > + * entry pointing to the new page. > + */ > + vcpu->kvm->arch.apic_access_page = gfn_to_page(vcpu->kvm, > + APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT); > + kvm_x86_ops->set_apic_access_page_addr(vcpu->kvm, > + page_to_phys(vcpu->kvm->arch.apic_access_page)); I am a little bit worried that here all vcpus write to vcpu->kvm->arch.apic_access_page without any locking. It is probably benign since pointer write is atomic on x86. Paolo? Do we even need apic_access_page? Why not call gfn_to_page(APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT) put_page() on rare occasions we need to know its address? > +} > + > /* > * Returns 1 to let __vcpu_run() continue the guest execution loop without > * exiting to the userspace. Otherwise, the value will be returned to the > @@ -6049,6 +6062,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) > kvm_deliver_pmi(vcpu); > if (kvm_check_request(KVM_REQ_SCAN_IOAPIC, vcpu)) > vcpu_scan_ioapic(vcpu); > + if (kvm_check_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu)) > + vcpu_reload_apic_access_page(vcpu); > } > > if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) { > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index a4c33b3..8be076a 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -136,6 +136,7 @@ static inline bool is_error_page(struct page *page) > #define KVM_REQ_GLOBAL_CLOCK_UPDATE 22 > #define KVM_REQ_ENABLE_IBS 23 > #define KVM_REQ_DISABLE_IBS 24 > +#define KVM_REQ_APIC_PAGE_RELOAD 25 > > #define KVM_USERSPACE_IRQ_SOURCE_ID 0 > #define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID 1 > @@ -579,6 +580,7 @@ void kvm_flush_remote_tlbs(struct kvm *kvm); > void kvm_reload_remote_mmus(struct kvm *kvm); > void kvm_make_mclock_inprogress_request(struct kvm *kvm); > void kvm_make_scan_ioapic_request(struct kvm *kvm); > +void kvm_reload_apic_access_page(struct kvm *kvm); > > long kvm_arch_dev_ioctl(struct file *filp, > unsigned int ioctl, unsigned long arg); > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 33712fb..d8280de 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -210,6 +210,11 @@ void kvm_make_scan_ioapic_request(struct kvm *kvm) > make_all_cpus_request(kvm, KVM_REQ_SCAN_IOAPIC); > } > > +void kvm_reload_apic_access_page(struct kvm *kvm) > +{ > + make_all_cpus_request(kvm, KVM_REQ_APIC_PAGE_RELOAD); > +} > + > int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id) > { > struct page *page; > @@ -294,6 +299,13 @@ static void kvm_mmu_notifier_invalidate_page(struct mmu_notifier *mn, > if (need_tlb_flush) > kvm_flush_remote_tlbs(kvm); > > + /* > + * The physical address of apic access page is stroed in VMCS. > + * So need to update it when it becomes invalid. > + */ > + if (address == gfn_to_hva(kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT)) > + kvm_reload_apic_access_page(kvm); > + > spin_unlock(&kvm->mmu_lock); > srcu_read_unlock(&kvm->srcu, idx); > } > -- > 1.8.3.1 > -- Gleb.