LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Paolo Bonzini <pbonzini@redhat.com>
To: Maxim Levitsky <mlevitsk@redhat.com>, kvm@vger.kernel.org
Cc: Wanpeng Li <wanpengli@tencent.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Joerg Roedel <joro@8bytes.org>, Borislav Petkov <bp@alien8.de>,
	Sean Christopherson <seanjc@google.com>,
	Jim Mattson <jmattson@google.com>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>,
	"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
	<linux-kernel@vger.kernel.org>,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v3 09/12] KVM: x86: hyper-v: Deactivate APICv only when AutoEOI feature is in use
Date: Tue, 3 Aug 2021 11:01:10 +0200	[thread overview]
Message-ID: <4209384b-68f3-a0d2-24da-3b047422f114@redhat.com> (raw)
In-Reply-To: <20210802183329.2309921-10-mlevitsk@redhat.com>

On 02/08/21 20:33, Maxim Levitsky wrote:
> From: Vitaly Kuznetsov <vkuznets@redhat.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
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
>   arch/x86/include/asm/kvm_host.h |  3 +++
>   arch/x86/kvm/hyperv.c           | 27 +++++++++++++++++++++------
>   2 files changed, 24 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 80323b5fb20a..55b1f79d9c43 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -988,6 +988,9 @@ struct kvm_hv {
>   	/* How many vCPUs have VP index != vCPU index */
>   	atomic_t num_mismatched_vp_indexes;
>   
> +	/* How many SynICs use 'AutoEOI' feature */
> +	atomic_t 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..638f3c559623 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 +100,25 @@ 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);
> +
> +	/* Hyper-V SynIC auto EOI SINTs are not compatible with APICV */
> +	if (!auto_eoi_old && auto_eoi_new) {
> +		if (atomic_inc_return(&hv->synic_auto_eoi_used) == 1)
> +			kvm_request_apicv_update(vcpu->kvm, false,
> +						APICV_INHIBIT_REASON_HYPERV);
> +	} else if (!auto_eoi_new && auto_eoi_old) {
> +		if (atomic_dec_return(&hv->synic_auto_eoi_used) == 0)
> +			kvm_request_apicv_update(vcpu->kvm, true,
> +						APICV_INHIBIT_REASON_HYPERV);
> +	}
>   }
>   
>   static int synic_set_sint(struct kvm_vcpu_hv_synic *synic, int sint,
> @@ -933,12 +952,6 @@ 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 +2479,8 @@ 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.
> 

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>


  parent reply	other threads:[~2021-08-03  9:01 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-02 18:33 [PATCH v3 00/12] My AVIC patch queue Maxim Levitsky
2021-08-02 18:33 ` [PATCH v3 01/12] Revert "KVM: x86/mmu: Allow zap gfn range to operate under the mmu read lock" Maxim Levitsky
2021-08-03  8:05   ` Paolo Bonzini
2021-08-03 15:11     ` Sean Christopherson
2021-08-03 17:29       ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 02/12] KVM: x86/mmu: bump mmu notifier count in kvm_zap_gfn_range Maxim Levitsky
2021-08-03  9:00   ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 03/12] KVM: x86/mmu: rename try_async_pf to kvm_faultin_pfn Maxim Levitsky
2021-08-03  9:00   ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 04/12] KVM: x86/mmu: allow kvm_faultin_pfn to return page fault handling code Maxim Levitsky
2021-08-03  9:00   ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 05/12] KVM: x86/mmu: allow APICv memslot to be partially enabled Maxim Levitsky
2021-08-03  9:12   ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 06/12] KVM: x86: don't disable APICv memslot when inhibited Maxim Levitsky
2021-08-03  8:44   ` Paolo Bonzini
2021-08-09 18:51     ` Maxim Levitsky
2021-08-09 19:14       ` Sean Christopherson
2021-08-02 18:33 ` [PATCH v3 07/12] KVM: x86: APICv: fix race in kvm_request_apicv_update on SVM Maxim Levitsky
2021-08-02 18:33 ` [PATCH v3 08/12] KVM: SVM: add warning for mistmatch between AVIC state and AVIC access page state Maxim Levitsky
2021-08-03  8:45   ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 09/12] KVM: x86: hyper-v: Deactivate APICv only when AutoEOI feature is in use Maxim Levitsky
2021-08-03  8:47   ` Paolo Bonzini
2021-08-03  9:01   ` Paolo Bonzini [this message]
2021-08-03  9:11   ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 10/12] KVM: SVM: remove svm_toggle_avic_for_irq_window Maxim Levitsky
2021-08-03  9:11   ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 11/12] KVM: SVM: call avic_vcpu_load/avic_vcpu_put when enabling/disabling AVIC Maxim Levitsky
2021-08-03  9:00   ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 12/12] KVM: SVM: AVIC: drop unsupported AVIC base relocation code Maxim Levitsky

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4209384b-68f3-a0d2-24da-3b047422f114@redhat.com \
    --to=pbonzini@redhat.com \
    --cc=bp@alien8.de \
    --cc=hpa@zytor.com \
    --cc=jmattson@google.com \
    --cc=joro@8bytes.org \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=mlevitsk@redhat.com \
    --cc=seanjc@google.com \
    --cc=suravee.suthikulpanit@amd.com \
    --cc=tglx@linutronix.de \
    --cc=vkuznets@redhat.com \
    --cc=wanpengli@tencent.com \
    --cc=x86@kernel.org \
    --subject='Re: [PATCH v3 09/12] KVM: x86: hyper-v: Deactivate APICv only when AutoEOI feature is in use' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).