From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Ben Gardon <bgardon@google.com>,
Junaid Shahid <junaids@google.com>,
Liran Alon <liran.alon@oracle.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
John Haxby <john.haxby@oracle.com>,
Miaohe Lin <linmiaohe@huawei.com>,
Tom Lendacky <thomas.lendacky@amd.com>
Subject: Re: [PATCH v2 23/32] KVM: nVMX: Add helper to handle TLB flushes on nested VM-Enter/VM-Exit
Date: Tue, 17 Mar 2020 11:18:32 -0700 [thread overview]
Message-ID: <20200317181832.GC12959@linux.intel.com> (raw)
In-Reply-To: <0975d43f-42b6-74db-f916-b0995115d726@redhat.com>
On Tue, Mar 17, 2020 at 06:17:59PM +0100, Paolo Bonzini wrote:
> On 17/03/20 05:52, Sean Christopherson wrote:
> > + nested_vmx_transition_tlb_flush(vcpu, vmcs12);
> > +
> > + /*
> > + * There is no direct mapping between vpid02 and vpid12, vpid02 is
> > + * per-vCPU and reused for all nested vCPUs. If vpid12 is changing
> > + * then the new "virtual" VPID will reuse the same "real" VPID,
> > + * vpid02, and so needs to be sync'd. Skip the sync if a TLB flush
> > + * has already been requested, but always update the last used VPID.
> > + */
> > + if (nested_cpu_has_vpid(vmcs12) && nested_has_guest_tlb_tag(vcpu) &&
> > + vmcs12->virtual_processor_id != vmx->nested.last_vpid) {
> > + vmx->nested.last_vpid = vmcs12->virtual_processor_id;
> > + if (!kvm_test_request(KVM_REQ_TLB_FLUSH, vcpu))
> > + vpid_sync_context(nested_get_vpid02(vcpu));
> > }
>
> Would it make sense to move nested_vmx_transition_tlb_flush into an
> "else" branch?
Maybe? I tried that at one point, but didn't like making the call to
nested_vmx_transition_tlb_flush() conditional. My intent is to have
the ...tlb_flush() call be standalone, i.e. logic that is common to all
nested transitions, so that someone can look at the code can easily
(relatively speaking) understand the basic rules for TLB flushing on
nested transitions.
I also tried the oppositie, i.e. putting the above code in an else-branch,
with nested_vmx_transition_tlb_flush() returning true if it requested a
flush. But that required updating vmx->nested.last_vpid in a separate
flow, which was quite awkward.
> And should this also test that KVM_REQ_TLB_FLUSH_CURRENT is not set?
Doh, yes.
next prev parent reply other threads:[~2020-03-17 18:18 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-17 4:52 [PATCH v2 00/32] KVM: x86: TLB flushing fixes and enhancements Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 01/32] KVM: VMX: Flush all EPTP/VPID contexts on remote TLB flush Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 02/32] KVM: nVMX: Validate the EPTP when emulating INVEPT(EXTENT_CONTEXT) Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 03/32] KVM: nVMX: Invalidate all EPTP contexts when emulating INVEPT for L1 Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 04/32] KVM: nVMX: Invalidate all L2 roots when emulating INVVPID without EPT Sean Christopherson
2020-03-20 4:11 ` Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 05/32] KVM: x86: Export kvm_propagate_fault() (as kvm_inject_emulated_page_fault) Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 06/32] KVM: x86: Consolidate logic for injecting page faults to L1 Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 07/32] KVM: x86: Sync SPTEs when injecting page/EPT fault into L1 Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 08/32] KVM: VMX: Skip global INVVPID fallback if vpid==0 in vpid_sync_context() Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 09/32] KVM: VMX: Use vpid_sync_context() directly when possible Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 10/32] KVM: VMX: Move vpid_sync_vcpu_addr() down a few lines Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 11/32] KVM: VMX: Handle INVVPID fallback logic in vpid_sync_vcpu_addr() Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 12/32] KVM: VMX: Drop redundant capability checks in low level INVVPID helpers Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 13/32] KVM: nVMX: Use vpid_sync_vcpu_addr() to emulate INVVPID with address Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 14/32] KVM: x86: Move "flush guest's TLB" logic to separate kvm_x86_ops hook Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 15/32] KVM: VMX: Clean up vmx_flush_tlb_gva() Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 16/32] KVM: x86: Drop @invalidate_gpa param from kvm_x86_ops' tlb_flush() Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 17/32] KVM: SVM: Wire up ->tlb_flush_guest() directly to svm_flush_tlb() Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 18/32] KVM: VMX: Move vmx_flush_tlb() to vmx.c Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 19/32] KVM: nVMX: Move nested_get_vpid02() to vmx/nested.h Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 20/32] KVM: VMX: Introduce vmx_flush_tlb_current() Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 21/32] KVM: SVM: Document the ASID logic in svm_flush_tlb() Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 22/32] KVM: x86: Rename ->tlb_flush() to ->tlb_flush_all() Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 23/32] KVM: nVMX: Add helper to handle TLB flushes on nested VM-Enter/VM-Exit Sean Christopherson
2020-03-17 17:17 ` Paolo Bonzini
2020-03-17 18:18 ` Sean Christopherson [this message]
2020-03-18 10:45 ` Paolo Bonzini
2020-03-18 16:09 ` Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 24/32] KVM: x86: Introduce KVM_REQ_TLB_FLUSH_CURRENT to flush current ASID Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 25/32] KVM: x86/mmu: Use KVM_REQ_TLB_FLUSH_CURRENT for MMU specific flushes Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 26/32] KVM: nVMX: Selectively use TLB_FLUSH_CURRENT for nested VM-Enter/VM-Exit Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 27/32] KVM: nVMX: Reload APIC access page on nested VM-Exit only if necessary Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 28/32] KVM: VMX: Retrieve APIC access page HPA only when necessary Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 29/32] KVM: VMX: Don't reload APIC access page if its control is disabled Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 30/32] KVM: x86/mmu: Add module param to force TLB flush on root reuse Sean Christopherson
2020-03-17 4:52 ` [PATCH v2 31/32] KVM: nVMX: Don't flush TLB on nested VM transition with EPT enabled Sean Christopherson
2020-03-17 17:18 ` Paolo Bonzini
2020-03-17 18:22 ` Sean Christopherson
2020-03-18 10:36 ` Paolo Bonzini
2020-03-18 17:02 ` Sean Christopherson
2020-03-18 17:11 ` Paolo Bonzini
2020-03-18 17:26 ` Sean Christopherson
2020-03-18 17:38 ` Paolo Bonzini
2020-03-17 4:52 ` [PATCH v2 32/32] KVM: nVMX: Free only the affected contexts when emulating INVEPT Sean Christopherson
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