From: Sean Christopherson <seanjc@google.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
Michael Kelley <mikelley@microsoft.com>,
Siddharth Chandrasekaran <sidcha@amazon.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 01/31] KVM: x86: hyper-v: Resurrect dedicated KVM_REQ_HV_TLB_FLUSH flag
Date: Thu, 7 Apr 2022 18:02:36 +0000 [thread overview]
Message-ID: <Yk8nPJ45PJzN9o+L@google.com> (raw)
In-Reply-To: <20220407155645.940890-2-vkuznets@redhat.com>
On Thu, Apr 07, 2022, Vitaly Kuznetsov wrote:
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index e9647614dc8c..3c54f6804b7b 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3341,7 +3341,12 @@ void kvm_service_local_tlb_flush_requests(struct kvm_vcpu *vcpu)
> if (kvm_check_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu))
> kvm_vcpu_flush_tlb_current(vcpu);
>
> - if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu))
> + if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu)) {
> + kvm_vcpu_flush_tlb_guest(vcpu);
> + kvm_clear_request(KVM_REQ_HV_TLB_FLUSH, vcpu);
> + }
> +
> + if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu))
> kvm_vcpu_flush_tlb_guest(vcpu);
It'd be slightly more performant to do:
if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu)) {
kvm_vcpu_flush_tlb_guest(vcpu);
kvm_clear_request(KVM_REQ_HV_TLB_FLUSH, vcpu);
} else if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu)) {
kvm_hv_vcpu_flush_tlb(vcpu);
}
And then when the code becomes
if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu)) {
kvm_vcpu_flush_tlb_guest(vcpu);
if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu))
kvm_hv_vcpu_empty_flush_tlb(vcpu);
} else if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu)) {
kvm_hv_vcpu_flush_tlb(vcpu);
}
the elif will help unsuspecting readers see that the HV_TLB_FLUSH request is
cleared by kvm_check_request() in the TLB_FLUSH_GUEST path.
The elif could result in having to bail from VM-Entry if the request becomes
pending after the check/clear inside TLB_FLUSH_GUEST, but that should be a very
rare case.
> }
> EXPORT_SYMBOL_GPL(kvm_service_local_tlb_flush_requests);
> --
> 2.35.1
>
next prev parent reply other threads:[~2022-04-07 18:02 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-07 15:56 [PATCH v2 00/31] KVM: x86: hyper-v: Fine-grained TLB flush + Direct TLB flush feature Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 01/31] KVM: x86: hyper-v: Resurrect dedicated KVM_REQ_HV_TLB_FLUSH flag Vitaly Kuznetsov
2022-04-07 18:02 ` Sean Christopherson [this message]
2022-04-07 15:56 ` [PATCH v2 02/31] KVM: x86: hyper-v: Introduce TLB flush ring Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 03/31] KVM: x86: hyper-v: Handle HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST{,EX} calls gently Vitaly Kuznetsov
2022-04-07 17:33 ` Sean Christopherson
2022-04-07 17:47 ` Sean Christopherson
2022-04-11 11:15 ` Vitaly Kuznetsov
2022-04-07 17:44 ` Sean Christopherson
2022-04-11 11:31 ` Vitaly Kuznetsov
2022-04-11 20:37 ` Sean Christopherson
2022-04-07 15:56 ` [PATCH v2 04/31] KVM: x86: hyper-v: Expose support for extended gva ranges for flush hypercalls Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 05/31] KVM: x86: Prepare kvm_hv_flush_tlb() to handle L2's GPAs Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 06/31] KVM: x86: hyper-v: Don't use sparse_set_to_vcpu_mask() in kvm_hv_send_ipi() Vitaly Kuznetsov
2022-04-07 17:48 ` Sean Christopherson
2022-04-07 15:56 ` [PATCH v2 07/31] KVM: x86: hyper-v: Create a separate ring for Direct TLB flush Vitaly Kuznetsov
2022-04-07 17:57 ` Sean Christopherson
2022-04-07 15:56 ` [PATCH v2 08/31] KVM: x86: hyper-v: Use preallocated buffer in 'struct kvm_vcpu_hv' instead of on-stack 'sparse_banks' Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 09/31] KVM: nVMX: Keep track of hv_vm_id/hv_vp_id when eVMCS is in use Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 10/31] KVM: nSVM: Keep track of Hyper-V hv_vm_id/hv_vp_id Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 11/31] KVM: x86: Introduce .post_hv_direct_flush() nested hook Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 12/31] KVM: x86: hyper-v: Introduce kvm_hv_is_tlb_flush_hcall() Vitaly Kuznetsov
2022-04-07 18:07 ` Sean Christopherson
2022-04-07 15:56 ` [PATCH v2 13/31] KVM: x86: hyper-v: Direct TLB flush Vitaly Kuznetsov
2022-04-07 18:27 ` Sean Christopherson
2022-04-14 12:24 ` Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 14/31] KVM: x86: hyper-v: Introduce fast kvm_hv_direct_tlb_flush_exposed() check Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 15/31] x86/hyperv: Fix 'struct hv_enlightened_vmcs' definition Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 16/31] KVM: nVMX: hyper-v: Direct TLB flush Vitaly Kuznetsov
2022-04-07 18:47 ` Sean Christopherson
2022-04-11 11:19 ` Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 17/31] KVM: x86: KVM_REQ_TLB_FLUSH_CURRENT is a superset of KVM_REQ_HV_TLB_FLUSH too Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 18/31] KVM: nSVM: hyper-v: Direct TLB flush Vitaly Kuznetsov
2022-04-07 18:50 ` Sean Christopherson
2022-04-07 15:56 ` [PATCH v2 19/31] KVM: x86: Expose Hyper-V Direct TLB flush feature Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 20/31] KVM: selftests: add hyperv_svm_test to .gitignore Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 21/31] KVM: selftests: Better XMM read/write helpers Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 22/31] KVM: selftests: Hyper-V PV IPI selftest Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 23/31] KVM: selftests: Make it possible to replace PTEs with __virt_pg_map() Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 24/31] KVM: selftests: Hyper-V PV TLB flush selftest Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 25/31] KVM: selftests: Sync 'struct hv_enlightened_vmcs' definition with hyperv-tlfs.h Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 26/31] KVM: selftests: nVMX: Allocate Hyper-V partition assist page Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 27/31] KVM: selftests: nSVM: Allocate Hyper-V partition assist and VP assist pages Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 28/31] KVM: selftests: Sync 'struct hv_vp_assist_page' definition with hyperv-tlfs.h Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 29/31] KVM: selftests: evmcs_test: Direct TLB flush test Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 30/31] KVM: selftests: Move Hyper-V VP assist page enablement out of evmcs.h Vitaly Kuznetsov
2022-04-07 15:56 ` [PATCH v2 31/31] KVM: selftests: hyperv_svm_test: Add Direct TLB flush test Vitaly Kuznetsov
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