lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 10 Aug 2021 23:52:46 +0300 From: Maxim Levitsky <mlevitsk@...hat.com> To: kvm@...r.kernel.org Cc: Jim Mattson <jmattson@...gle.com>, linux-kernel@...r.kernel.org, Wanpeng Li <wanpengli@...cent.com>, Borislav Petkov <bp@...en8.de>, Joerg Roedel <joro@...tes.org>, Suravee Suthikulpanit <suravee.suthikulpanit@....com>, "H. Peter Anvin" <hpa@...or.com>, Paolo Bonzini <pbonzini@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Vitaly Kuznetsov <vkuznets@...hat.com>, Sean Christopherson <seanjc@...gle.com>, x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)), Maxim Levitsky <mlevitsk@...hat.com> Subject: [PATCH v4 11/16] KVM: x86: hyper-v: Deactivate APICv only when AutoEOI feature is in use From: Vitaly Kuznetsov <vkuznets@...hat.com> APICV_INHIBIT_REASON_HYPERV is currently unconditionally forced upon SynIC activation as SynIC's AutoEOI is incompatible with APICv/AVIC. It is, however, possible to track whether the feature was actually used by the guest and only inhibit APICv/AVIC when needed. TLFS suggests a dedicated 'HV_DEPRECATING_AEOI_RECOMMENDED' flag to let Windows know that AutoEOI feature should be avoided. While it's up to KVM userspace to set the flag, KVM can help a bit by exposing global APICv/AVIC enablement. Maxim: - always set HV_DEPRECATING_AEOI_RECOMMENDED in kvm_get_hv_cpuid, since this feature can be used regardless of AVIC Paolo: - use arch.apicv_update_lock to protect the hv->synic_auto_eoi_used instead of atomic ops Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com> Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com> --- arch/x86/include/asm/kvm_host.h | 6 ++++++ arch/x86/kvm/hyperv.c | 32 ++++++++++++++++++++++++++------ 2 files changed, 32 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 27627e32f362..a0ddff8d13c4 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -982,6 +982,12 @@ struct kvm_hv { /* How many vCPUs have VP index != vCPU index */ atomic_t num_mismatched_vp_indexes; + /* + * How many SynICs use 'AutoEOI' feature + * (protected by arch.apicv_update_lock) + */ + unsigned int synic_auto_eoi_used; + struct hv_partition_assist_pg *hv_pa_pg; struct kvm_hv_syndbg hv_syndbg; }; diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index b07592ca92f0..031ea0fb3e2f 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -88,6 +88,10 @@ static bool synic_has_vector_auto_eoi(struct kvm_vcpu_hv_synic *synic, static void synic_update_vector(struct kvm_vcpu_hv_synic *synic, int vector) { + struct kvm_vcpu *vcpu = hv_synic_to_vcpu(synic); + struct kvm_hv *hv = to_kvm_hv(vcpu->kvm); + int auto_eoi_old, auto_eoi_new; + if (vector < HV_SYNIC_FIRST_VALID_VECTOR) return; @@ -96,10 +100,30 @@ static void synic_update_vector(struct kvm_vcpu_hv_synic *synic, else __clear_bit(vector, synic->vec_bitmap); + auto_eoi_old = bitmap_weight(synic->auto_eoi_bitmap, 256); + if (synic_has_vector_auto_eoi(synic, vector)) __set_bit(vector, synic->auto_eoi_bitmap); else __clear_bit(vector, synic->auto_eoi_bitmap); + + auto_eoi_new = bitmap_weight(synic->auto_eoi_bitmap, 256); + + if (!!auto_eoi_old == !!auto_eoi_new) + return; + + mutex_lock(&vcpu->kvm->arch.apicv_update_lock); + + if (auto_eoi_new) + hv->synic_auto_eoi_used++; + else + hv->synic_auto_eoi_used--; + + __kvm_request_apicv_update(vcpu->kvm, + !hv->synic_auto_eoi_used, + APICV_INHIBIT_REASON_HYPERV); + + mutex_unlock(&vcpu->kvm->arch.apicv_update_lock); } static int synic_set_sint(struct kvm_vcpu_hv_synic *synic, int sint, @@ -933,12 +957,6 @@ int kvm_hv_activate_synic(struct kvm_vcpu *vcpu, bool dont_zero_synic_pages) synic = to_hv_synic(vcpu); - /* - * Hyper-V SynIC auto EOI SINT's are - * not compatible with APICV, so request - * to deactivate APICV permanently. - */ - kvm_request_apicv_update(vcpu->kvm, false, APICV_INHIBIT_REASON_HYPERV); synic->active = true; synic->dont_zero_synic_pages = dont_zero_synic_pages; synic->control = HV_SYNIC_CONTROL_ENABLE; @@ -2466,6 +2484,8 @@ int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid, ent->eax |= HV_X64_ENLIGHTENED_VMCS_RECOMMENDED; if (!cpu_smt_possible()) ent->eax |= HV_X64_NO_NONARCH_CORESHARING; + + ent->eax |= HV_DEPRECATING_AEOI_RECOMMENDED; /* * Default number of spinlock retry attempts, matches * HyperV 2016. -- 2.26.3
Powered by blists - more mailing lists