From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Vineeth Pillai <viremana@linux.microsoft.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"K. Y. Srinivasan" <kys@microsoft.com>,
x86@kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
Lan Tianyu <Tianyu.Lan@microsoft.com>,
Michael Kelley <mikelley@microsoft.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Wei Liu <wei.liu@kernel.org>,
Stephen Hemminger <sthemmin@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>
Subject: Re: [PATCH 7/7] KVM: SVM: hyper-v: Direct Virtual Flush support
Date: Thu, 08 Apr 2021 13:25:54 +0200 [thread overview]
Message-ID: <87a6q9augt.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <aa634c867aa395aa2d3eae950dfec137f59a62c6.1617804573.git.viremana@linux.microsoft.com>
Vineeth Pillai <viremana@linux.microsoft.com> writes:
> From Hyper-V TLFS:
> "The hypervisor exposes hypercalls (HvFlushVirtualAddressSpace,
> HvFlushVirtualAddressSpaceEx, HvFlushVirtualAddressList, and
> HvFlushVirtualAddressListEx) that allow operating systems to more
> efficiently manage the virtual TLB. The L1 hypervisor can choose to
> allow its guest to use those hypercalls and delegate the responsibility
> to handle them to the L0 hypervisor. This requires the use of a
> partition assist page."
>
> Add the Direct Virtual Flush support for SVM.
>
> Related VMX changes:
> commit 6f6a657c9998 ("KVM/Hyper-V/VMX: Add direct tlb flush support")
>
> Signed-off-by: Vineeth Pillai <viremana@linux.microsoft.com>
> ---
> arch/x86/kvm/svm/svm.c | 48 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 48 insertions(+)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 3562a247b7e8..c6d3f3a7c986 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -440,6 +440,32 @@ static void svm_init_osvw(struct kvm_vcpu *vcpu)
> vcpu->arch.osvw.status |= 1;
> }
>
> +#if IS_ENABLED(CONFIG_HYPERV)
> +static int hv_enable_direct_tlbflush(struct kvm_vcpu *vcpu)
> +{
> + struct hv_enlightenments *hve;
> + struct hv_partition_assist_pg **p_hv_pa_pg =
> + &to_kvm_hv(vcpu->kvm)->hv_pa_pg;
> +
> + if (!*p_hv_pa_pg)
> + *p_hv_pa_pg = kzalloc(PAGE_SIZE, GFP_KERNEL);
> +
> + if (!*p_hv_pa_pg)
> + return -ENOMEM;
> +
> + hve = (struct hv_enlightenments *)&to_svm(vcpu)->vmcb->hv_enlightenments;
> +
> + hve->partition_assist_page = __pa(*p_hv_pa_pg);
> + hve->hv_vm_id = (unsigned long)vcpu->kvm;
> + if (!hve->hv_enlightenments_control.nested_flush_hypercall) {
> + hve->hv_enlightenments_control.nested_flush_hypercall = 1;
> + vmcb_mark_dirty(to_svm(vcpu)->vmcb, VMCB_HV_NESTED_ENLIGHTENMENTS);
> + }
> +
> + return 0;
> +}
> +#endif
> +
> static int has_svm(void)
> {
> const char *msg;
> @@ -1034,6 +1060,21 @@ static __init int svm_hardware_setup(void)
> svm_x86_ops.tlb_remote_flush_with_range =
> kvm_hv_remote_flush_tlb_with_range;
> }
> +
> + if (ms_hyperv.nested_features & HV_X64_NESTED_DIRECT_FLUSH) {
> + pr_info("kvm: Hyper-V Direct TLB Flush enabled\n");
> + for_each_online_cpu(cpu) {
> + struct hv_vp_assist_page *vp_ap =
> + hv_get_vp_assist_page(cpu);
> +
> + if (!vp_ap)
> + continue;
> +
> + vp_ap->nested_control.features.directhypercall = 1;
> + }
> + svm_x86_ops.enable_direct_tlbflush =
> + hv_enable_direct_tlbflush;
> + }
> #endif
>
> if (nrips) {
> @@ -3913,6 +3954,13 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
> }
> svm->vmcb->save.cr2 = vcpu->arch.cr2;
>
> +#if IS_ENABLED(CONFIG_HYPERV)
> + if (svm->vmcb->hv_enlightenments.hv_vp_id != to_hv_vcpu(vcpu)->vp_index) {
This looks wrong (see my previous comment about mixing KVM-on-Hyper-V
and Windows/Hyper-V-on-KVM). 'to_hv_vcpu(vcpu)->vp_index' is
'Windows/Hyper-V-on-KVM' thingy, it does not exist when we run without
any Hyper-V enlightenments exposed (e.g. when we run Linux as our
guest).
> + svm->vmcb->hv_enlightenments.hv_vp_id = to_hv_vcpu(vcpu)->vp_index;
> + vmcb_mark_dirty(svm->vmcb, VMCB_HV_NESTED_ENLIGHTENMENTS);
> + }
> +#endif
> +
> /*
> * Run with all-zero DR6 unless needed, so that we can get the exact cause
> * of a #DB.
--
Vitaly
prev parent reply other threads:[~2021-04-08 11:26 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-07 14:41 [PATCH 0/7] Hyper-V nested virt enlightenments for SVM Vineeth Pillai
2021-04-07 14:41 ` [PATCH 1/7] hyperv: Detect Nested virtualization support " Vineeth Pillai
2021-04-07 16:09 ` Borislav Petkov
2021-04-07 19:55 ` Michael Kelley
2021-04-07 22:48 ` Sean Christopherson
2021-04-08 13:26 ` Vineeth Pillai
2021-04-08 11:06 ` Vitaly Kuznetsov
2021-04-08 13:15 ` Vineeth Pillai
2021-04-08 15:24 ` Sean Christopherson
2021-04-09 12:23 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 2/7] hyperv: SVM enlightened TLB flush support flag Vineeth Pillai
2021-04-07 19:56 ` Michael Kelley
2021-04-08 13:45 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 3/7] KVM: x86: hyper-v: Move the remote TLB flush logic out of vmx Vineeth Pillai
2021-04-08 11:14 ` Vitaly Kuznetsov
2021-04-08 13:18 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 4/7] KVM: SVM: hyper-v: Nested enlightenments in VMCB Vineeth Pillai
2021-04-08 15:44 ` Paolo Bonzini
2021-04-09 12:24 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 5/7] KVM: SVM: hyper-v: Remote TLB flush for SVM Vineeth Pillai
2021-04-08 11:18 ` Vitaly Kuznetsov
2021-04-08 13:19 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 6/7] KVM: SVM: hyper-v: Enlightened MSR-Bitmap support Vineeth Pillai
2021-04-08 11:22 ` Vitaly Kuznetsov
2021-04-08 15:47 ` Paolo Bonzini
2021-04-07 14:41 ` [PATCH 7/7] KVM: SVM: hyper-v: Direct Virtual Flush support Vineeth Pillai
2021-04-08 11:25 ` Vitaly Kuznetsov [this message]
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