From 4592b7eaa87d3525825d4ab2a35308bcec9e5ff9 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Tue, 26 Jan 2021 14:48:13 +0100 Subject: [PATCH] KVM: x86: hyper-v: Allocate 'struct kvm_vcpu_hv' dynamically Hyper-V context is only needed for guests which use Hyper-V emulation in KVM (e.g. Windows/Hyper-V guests). 'struct kvm_vcpu_hv' is, however, quite big, it accounts for more than 1/4 of the total 'struct kvm_vcpu_arch' which is also quite big already. This all looks like a waste. Allocate 'struct kvm_vcpu_hv' dynamically. This patch does not bring any (intentional) functional change as we still allocate the context unconditionally but it paves the way to doing that only when needed. Signed-off-by: Vitaly Kuznetsov Message-Id: <20210126134816.1880136-13-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 3 ++- arch/x86/kvm/hyperv.c | 16 ++++++++++++++-- arch/x86/kvm/hyperv.h | 13 ++++++------- arch/x86/kvm/x86.c | 7 +++++-- 4 files changed, 27 insertions(+), 12 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index b6de568e7476..95eb6e93a4b7 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -519,6 +519,7 @@ struct kvm_vcpu_hv_synic { /* Hyper-V per vcpu emulation context */ struct kvm_vcpu_hv { + struct kvm_vcpu *vcpu; u32 vp_index; u64 hv_vapic; s64 runtime_offset; @@ -735,7 +736,7 @@ struct kvm_vcpu_arch { /* used for guest single stepping over the given code position */ unsigned long singlestep_rip; - struct kvm_vcpu_hv hyperv; + struct kvm_vcpu_hv *hyperv; struct kvm_vcpu_xen xen; cpumask_var_t wbinvd_dirty_mask; diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 10e7ed2aa8fe..333bd200f186 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -837,6 +837,9 @@ void kvm_hv_vcpu_uninit(struct kvm_vcpu *vcpu) for (i = 0; i < ARRAY_SIZE(hv_vcpu->stimer); i++) stimer_cleanup(&hv_vcpu->stimer[i]); + + kfree(hv_vcpu); + vcpu->arch.hyperv = NULL; } bool kvm_hv_assist_page_enabled(struct kvm_vcpu *vcpu) @@ -886,16 +889,25 @@ static void stimer_init(struct kvm_vcpu_hv_stimer *stimer, int timer_index) stimer_prepare_msg(stimer); } -void kvm_hv_vcpu_init(struct kvm_vcpu *vcpu) +int kvm_hv_vcpu_init(struct kvm_vcpu *vcpu) { - struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu); + struct kvm_vcpu_hv *hv_vcpu; int i; + hv_vcpu = kzalloc(sizeof(struct kvm_vcpu_hv), GFP_KERNEL_ACCOUNT); + if (!hv_vcpu) + return -ENOMEM; + + vcpu->arch.hyperv = hv_vcpu; + hv_vcpu->vcpu = vcpu; + synic_init(&hv_vcpu->synic); bitmap_zero(hv_vcpu->stimer_pending_bitmap, HV_SYNIC_STIMER_COUNT); for (i = 0; i < ARRAY_SIZE(hv_vcpu->stimer); i++) stimer_init(&hv_vcpu->stimer[i], i); + + return 0; } void kvm_hv_vcpu_postcreate(struct kvm_vcpu *vcpu) diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h index 57e53a88f5eb..4bc2ab0caa92 100644 --- a/arch/x86/kvm/hyperv.h +++ b/arch/x86/kvm/hyperv.h @@ -57,20 +57,19 @@ static inline struct kvm_hv *to_kvm_hv(struct kvm *kvm) static inline struct kvm_vcpu_hv *to_hv_vcpu(struct kvm_vcpu *vcpu) { - return &vcpu->arch.hyperv; + return vcpu->arch.hyperv; } static inline struct kvm_vcpu *hv_vcpu_to_vcpu(struct kvm_vcpu_hv *hv_vcpu) { - struct kvm_vcpu_arch *arch; - - arch = container_of(hv_vcpu, struct kvm_vcpu_arch, hyperv); - return container_of(arch, struct kvm_vcpu, arch); + return hv_vcpu->vcpu; } static inline struct kvm_vcpu_hv_synic *to_hv_synic(struct kvm_vcpu *vcpu) { - return &vcpu->arch.hyperv.synic; + struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu); + + return &hv_vcpu->synic; } static inline struct kvm_vcpu *hv_synic_to_vcpu(struct kvm_vcpu_hv_synic *synic) @@ -101,7 +100,7 @@ int kvm_hv_synic_set_irq(struct kvm *kvm, u32 vcpu_id, u32 sint); void kvm_hv_synic_send_eoi(struct kvm_vcpu *vcpu, int vector); int kvm_hv_activate_synic(struct kvm_vcpu *vcpu, bool dont_zero_synic_pages); -void kvm_hv_vcpu_init(struct kvm_vcpu *vcpu); +int kvm_hv_vcpu_init(struct kvm_vcpu *vcpu); void kvm_hv_vcpu_postcreate(struct kvm_vcpu *vcpu); void kvm_hv_vcpu_uninit(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7caf95dadc93..a75d01523c4f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10083,11 +10083,12 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) vcpu->arch.pending_external_vector = -1; vcpu->arch.preempted_in_kernel = false; - kvm_hv_vcpu_init(vcpu); + if (kvm_hv_vcpu_init(vcpu)) + goto free_guest_fpu; r = static_call(kvm_x86_vcpu_create)(vcpu); if (r) - goto free_guest_fpu; + goto free_hv_vcpu; vcpu->arch.arch_capabilities = kvm_get_arch_capabilities(); vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT; @@ -10098,6 +10099,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) vcpu_put(vcpu); return 0; +free_hv_vcpu: + kvm_hv_vcpu_uninit(vcpu); free_guest_fpu: kvm_free_guest_fpu(vcpu); free_user_fpu: