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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: 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 v3 04/37] KVM: nVMX: Invalidate all roots when emulating INVVPID without EPT
Date: Mon, 23 Mar 2020 16:34:17 +0100	[thread overview]
Message-ID: <87v9mv84qu.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <20200320212833.3507-5-sean.j.christopherson@intel.com>

Sean Christopherson <sean.j.christopherson@intel.com> writes:

> From: Junaid Shahid <junaids@google.com>
>
> Free all roots when emulating INVVPID for L1 and EPT is disabled, as
> outstanding changes to the page tables managed by L1 need to be
> recognized.  Because L1 and L2 share an MMU when EPT is disabled, and
> because VPID is not tracked by the MMU role, all roots in the current
> MMU (root_mmu) need to be freed, otherwise a future nested VM-Enter or
> VM-Exit could do a fast CR3 switch (without a flush/sync) and consume
> stale SPTEs.
>
> Fixes: 5c614b3583e7b ("KVM: nVMX: nested VPID emulation")
> Signed-off-by: Junaid Shahid <junaids@google.com>
> [sean: ported to upstream KVM, reworded the comment and changelog]
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
>  arch/x86/kvm/vmx/nested.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 9624cea4ed9f..bc74fbbf33c6 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -5250,6 +5250,20 @@ static int handle_invvpid(struct kvm_vcpu *vcpu)
>  		return kvm_skip_emulated_instruction(vcpu);
>  	}
>  
> +	/*
> +	 * Sync the shadow page tables if EPT is disabled, L1 is invalidating
> +	 * linear mappings for L2 (tagged with L2's VPID).  Free all roots as
> +	 * VPIDs are not tracked in the MMU role.
> +	 *
> +	 * Note, this operates on root_mmu, not guest_mmu, as L1 and L2 share
> +	 * an MMU when EPT is disabled.
> +	 *
> +	 * TODO: sync only the affected SPTEs for INVDIVIDUAL_ADDR.
> +	 */
> +	if (!enable_ept)
> +		kvm_mmu_free_roots(vcpu, &vcpu->arch.root_mmu,
> +				   KVM_MMU_ROOTS_ALL);
> +

This is related to my remark on the previous patch; the comment above
makes me think I'm missing something obvious, enlighten me please)

My understanding is that L1 and L2 will share arch.root_mmu not only
when EPT is globally disabled, we seem to switch between
root_mmu/guest_mmu only when nested_cpu_has_ept(vmcs12) but different L2
guests may be different on this. Do we need to handle this somehow?

>  	return nested_vmx_succeed(vcpu);
>  }

-- 
Vitaly


  reply	other threads:[~2020-03-23 15:34 UTC|newest]

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-20 21:27 [PATCH v3 00/37] KVM: x86: TLB flushing fixes and enhancements Sean Christopherson
2020-03-20 21:27 ` [PATCH v3 01/37] KVM: VMX: Flush all EPTP/VPID contexts on remote TLB flush Sean Christopherson
2021-08-03  1:45   ` Lai Jiangshan
2021-08-03 15:39     ` Sean Christopherson
2021-08-04  3:11       ` Lai Jiangshan
2021-08-04 15:33         ` Sean Christopherson
2020-03-20 21:27 ` [PATCH v3 02/37] KVM: nVMX: Validate the EPTP when emulating INVEPT(EXTENT_CONTEXT) Sean Christopherson
2020-03-23 14:51   ` Vitaly Kuznetsov
2020-03-23 15:45     ` Sean Christopherson
2020-03-23 23:46       ` Paolo Bonzini
2020-03-20 21:27 ` [PATCH v3 03/37] KVM: nVMX: Invalidate all EPTP contexts when emulating INVEPT for L1 Sean Christopherson
2020-03-23 15:24   ` Vitaly Kuznetsov
2020-03-23 15:53     ` Sean Christopherson
2020-03-23 16:24   ` Jim Mattson
2020-03-23 16:28     ` Sean Christopherson
2020-03-23 16:36       ` Jim Mattson
2020-03-23 16:44         ` Sean Christopherson
2020-03-23 23:50           ` Paolo Bonzini
2020-03-24  0:12             ` Jim Mattson
2020-03-30 18:38               ` Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 04/37] KVM: nVMX: Invalidate all roots when emulating INVVPID without EPT Sean Christopherson
2020-03-23 15:34   ` Vitaly Kuznetsov [this message]
2020-03-23 16:04     ` Sean Christopherson
2020-03-23 16:33       ` Vitaly Kuznetsov
2020-03-23 16:50         ` Sean Christopherson
2020-03-23 16:57           ` Vitaly Kuznetsov
2020-03-20 21:28 ` [PATCH v3 05/37] KVM: x86: Export kvm_propagate_fault() (as kvm_inject_emulated_page_fault) Sean Christopherson
2020-03-23 15:47   ` Vitaly Kuznetsov
2020-03-23 16:24     ` Sean Christopherson
2020-03-23 23:56       ` Paolo Bonzini
2020-03-20 21:28 ` [PATCH v3 06/37] KVM: x86: Consolidate logic for injecting page faults to L1 Sean Christopherson
2020-03-24  0:47   ` Paolo Bonzini
2020-03-20 21:28 ` [PATCH v3 07/37] KVM: x86: Sync SPTEs when injecting page/EPT fault into L1 Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 08/37] KVM: VMX: Skip global INVVPID fallback if vpid==0 in vpid_sync_context() Sean Christopherson
2020-03-25  9:33   ` Vitaly Kuznetsov
2020-03-20 21:28 ` [PATCH v3 09/37] KVM: VMX: Use vpid_sync_context() directly when possible Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 10/37] KVM: VMX: Move vpid_sync_vcpu_addr() down a few lines Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 11/37] KVM: VMX: Handle INVVPID fallback logic in vpid_sync_vcpu_addr() Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 12/37] KVM: VMX: Drop redundant capability checks in low level INVVPID helpers Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 13/37] KVM: nVMX: Use vpid_sync_vcpu_addr() to emulate INVVPID with address Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 14/37] KVM: x86: Move "flush guest's TLB" logic to separate kvm_x86_ops hook Sean Christopherson
2020-03-25 10:23   ` Vitaly Kuznetsov
2020-03-25 15:41     ` Paolo Bonzini
2020-03-25 16:08       ` Vitaly Kuznetsov
2020-03-25 15:48     ` Sean Christopherson
2020-03-25 16:11       ` Vitaly Kuznetsov
2020-03-20 21:28 ` [PATCH v3 15/37] KVM: VMX: Clean up vmx_flush_tlb_gva() Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 16/37] KVM: x86: Drop @invalidate_gpa param from kvm_x86_ops' tlb_flush() Sean Christopherson
2020-03-25 11:23   ` Vitaly Kuznetsov
2020-03-20 21:28 ` [PATCH v3 17/37] KVM: SVM: Wire up ->tlb_flush_guest() directly to svm_flush_tlb() Sean Christopherson
2020-03-25 11:23   ` Vitaly Kuznetsov
2020-03-20 21:28 ` [PATCH v3 18/37] KVM: VMX: Move vmx_flush_tlb() to vmx.c Sean Christopherson
2020-03-25 11:25   ` Vitaly Kuznetsov
2020-03-20 21:28 ` [PATCH v3 19/37] KVM: nVMX: Move nested_get_vpid02() to vmx/nested.h Sean Christopherson
2020-03-25 11:25   ` Vitaly Kuznetsov
2020-03-20 21:28 ` [PATCH v3 20/37] KVM: VMX: Introduce vmx_flush_tlb_current() Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 21/37] KVM: SVM: Document the ASID logic in svm_flush_tlb() Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 22/37] KVM: x86: Rename ->tlb_flush() to ->tlb_flush_all() Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 23/37] KVM: nVMX: Add helper to handle TLB flushes on nested VM-Enter/VM-Exit Sean Christopherson
2021-10-28 13:11   ` Lai Jiangshan
2021-10-28 15:22     ` Sean Christopherson
2021-10-29  0:44       ` Lai Jiangshan
2021-10-29 17:10         ` Sean Christopherson
2021-10-30  1:34           ` Lai Jiangshan
2021-11-04 17:47             ` Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 24/37] KVM: x86: Introduce KVM_REQ_TLB_FLUSH_CURRENT to flush current ASID Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 25/37] KVM: x86/mmu: Use KVM_REQ_TLB_FLUSH_CURRENT for MMU specific flushes Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 26/37] KVM: nVMX: Selectively use TLB_FLUSH_CURRENT for nested VM-Enter/VM-Exit Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 27/37] KVM: nVMX: Reload APIC access page on nested VM-Exit only if necessary Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 28/37] KVM: VMX: Retrieve APIC access page HPA only when necessary Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 29/37] KVM: VMX: Don't reload APIC access page if its control is disabled Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 30/37] KVM: x86/mmu: Move fast_cr3_switch() side effects to __kvm_mmu_new_cr3() Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 31/37] KVM: x86/mmu: Add separate override for MMU sync during fast CR3 switch Sean Christopherson
2020-03-24 11:07   ` Paolo Bonzini
2020-03-20 21:28 ` [PATCH v3 32/37] KVM: x86/mmu: Add module param to force TLB flush on root reuse Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 33/37] KVM: nVMX: Skip MMU sync on nested VMX transition when possible Sean Christopherson
2020-03-24 11:19   ` Paolo Bonzini
2020-03-20 21:28 ` [PATCH v3 34/37] KVM: nVMX: Don't flush TLB on nested VMX transition Sean Christopherson
2020-03-24 11:20   ` Paolo Bonzini
2020-03-24 18:10     ` Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 35/37] KVM: nVMX: Free only the affected contexts when emulating INVEPT Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 36/37] KVM: x86: Replace "cr3" with "pgd" in "new cr3/pgd" related code Sean Christopherson
2020-03-20 21:28 ` [PATCH v3 37/37] KVM: VMX: Clean cr3/pgd handling in vmx_load_mmu_pgd() Sean Christopherson

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