Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751978AbaGLIE4 (ORCPT ); Sat, 12 Jul 2014 04:04:56 -0400 Received: from mail-we0-f170.google.com ([74.125.82.170]:59196 "EHLO mail-we0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751517AbaGLIEs (ORCPT ); Sat, 12 Jul 2014 04:04:48 -0400 Date: Sat, 12 Jul 2014 11:04:42 +0300 From: Gleb Natapov To: Tang Chen Cc: mtosatti@redhat.com, nadav.amit@gmail.com, 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 v2 5/5] kvm, mem-hotplug: Do not pin apic access page in memory. Message-ID: <20140712080442.GH4399@minantech.com> References: <1404824492-30095-1-git-send-email-tangchen@cn.fujitsu.com> <1404824492-30095-6-git-send-email-tangchen@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1404824492-30095-6-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 Tue, Jul 08, 2014 at 09:01:32PM +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. > By default kvm Linux guest uses x2apic, so APIC_ACCESS_ADDR mechanism is not used since no MMIO access to APIC is ever done. Have you tested this with "-cpu modelname,-x2apic" qemu flag? > Signed-off-by: Tang Chen > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/mmu.c | 11 +++++++++++ > arch/x86/kvm/svm.c | 6 ++++++ > arch/x86/kvm/vmx.c | 8 +++++++- > arch/x86/kvm/x86.c | 14 ++++++++++++++ > include/linux/kvm_host.h | 2 ++ > virt/kvm/kvm_main.c | 12 ++++++++++++ > 7 files changed, 53 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 62f973e..9ce6bfd 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -737,6 +737,7 @@ 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/mmu.c b/arch/x86/kvm/mmu.c > index 9314678..551693d 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -3427,6 +3427,17 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code, > level, gfn, pfn, prefault); > spin_unlock(&vcpu->kvm->mmu_lock); > > + /* > + * apic access page could be migrated. When the guest tries to access > + * the apic access page, ept violation will occur, and we can use GUP > + * to find the new page. > + * > + * GUP will wait till the migrate entry be replaced with the new page. > + */ > + if (gpa == APIC_DEFAULT_PHYS_BASE) > + vcpu->kvm->arch.apic_access_page = gfn_to_page_no_pin(vcpu->kvm, > + APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT); Shouldn't you make KVM_REQ_APIC_PAGE_RELOAD request here? > + > return r; > > out_unlock: > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 576b525..dc76f29 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -3612,6 +3612,11 @@ 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; > @@ -4365,6 +4370,7 @@ 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 5532ac8..f7c6313 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -3992,7 +3992,7 @@ static int alloc_apic_access_page(struct kvm *kvm) > if (r) > goto out; > > - page = gfn_to_page(kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT); > + page = gfn_to_page_no_pin(kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT); > if (is_error_page(page)) { > r = -EFAULT; > goto out; > @@ -7073,6 +7073,11 @@ 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; > @@ -8842,6 +8847,7 @@ 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 ffbe557..7080eda 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -5929,6 +5929,18 @@ 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) > +{ > + /* > + * 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. > + */ > + struct page *page = gfn_to_page_no_pin(vcpu->kvm, > + APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT); If you do not use kvm->arch.apic_access_page to get current address why not drop it entirely? > + kvm_x86_ops->set_apic_access_page_addr(vcpu->kvm, > + page_to_phys(page)); > +} > + > /* > * Returns 1 to let __vcpu_run() continue the guest execution loop without > * exiting to the userspace. Otherwise, the value will be returned to the > @@ -5989,6 +6001,8 @@ 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 7c58d9d..f49be86 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 > @@ -596,6 +597,7 @@ 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 6091849..965b702 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); > } You forgot to drop put_page(kvm->arch.apic_access_page); from x86.c again. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/