From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <seanjc@google.com>,
Maxim Levitsky <mlevitsk@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Wanpeng Li <wanpengli@tencent.com>,
Borislav Petkov <bp@alien8.de>, Joerg Roedel <joro@8bytes.org>,
Jim Mattson <jmattson@google.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH 6/7] KVM: nVMX: don't load PDPTRS right after nested state set
Date: Wed, 17 Feb 2021 19:06:32 +0100 [thread overview]
Message-ID: <8660e415-5375-d4cf-54d4-b0b8eb6e1dc3@redhat.com> (raw)
In-Reply-To: <YC1X2FMdPn32ci1C@google.com>
On 17/02/21 18:52, Sean Christopherson wrote:
>>
>> Just move the call to nested_vmx_load_cr3 to nested_get_vmcs12_pages
>> to implement this.
>
> I don't love this approach. KVM_SET_NESTED_STATE will now succeed with a bad
> vmcs12.GUEST_CR3. At a minimum, GUEST_CR3 should be checked in
> nested_vmx_check_guest_state(). It also feels like vcpu->arch.cr3 should be set
> immediately, e.g. KVM_SET_NESTED_STATE -> KVM_GET_SREGS should reflect L2's CR3
> even if KVM_RUN hasn't been invoked.
Note that KVM_SET_NESTED_STATE does not remove the need to invoke
KVM_SET_SREGS. Calling KVM_SET_NESTED_STATE does not necessarily saying
anything about the value of KVM_GET_SREGS after it.
In particular on SVM it's a "feature" that KVM_SET_NESTED_STATE does not
include any guest register state; the nested state only includes the
VMCB12 control state and the L1 save state. But thinking more about it,
loading the PDPTRs for the guest CR3 might not be advisable even upon
KVM_SET_SREGS, and we might want to extend KVM_REQ_GET_NESTED_PAGES to
cover non-nested PDPTRs as well.
Paolo
next prev parent reply other threads:[~2021-02-17 18:08 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-17 14:57 [PATCH 0/7] KVM: random nested fixes Maxim Levitsky
2021-02-17 14:57 ` [PATCH 1/7] KVM: VMX: read idt_vectoring_info a bit earlier Maxim Levitsky
2021-02-17 16:06 ` Paolo Bonzini
2021-02-17 16:18 ` Maxim Levitsky
2021-02-17 16:21 ` Sean Christopherson
2021-02-17 16:29 ` Paolo Bonzini
2021-02-17 14:57 ` [PATCH 2/7] KVM: nSVM: move nested vmrun tracepoint to enter_svm_guest_mode Maxim Levitsky
2021-02-17 14:57 ` [PATCH 3/7] KVM: x86: add .complete_mmu_init arch callback Maxim Levitsky
2021-02-17 14:57 ` [PATCH 4/7] KVM: nVMX: move inject_page_fault tweak to .complete_mmu_init Maxim Levitsky
2021-02-17 17:29 ` Sean Christopherson
2021-02-17 17:37 ` Paolo Bonzini
2021-02-17 17:57 ` Sean Christopherson
2021-02-17 18:00 ` Paolo Bonzini
2021-02-17 18:49 ` Maxim Levitsky
2021-02-17 18:43 ` Maxim Levitsky
2021-02-18 9:45 ` Paolo Bonzini
2021-02-17 14:57 ` [PATCH 5/7] KVM: nSVM: fix running nested guests when npt=0 Maxim Levitsky
2021-02-17 15:27 ` Maxim Levitsky
2021-02-17 14:57 ` [PATCH 6/7] KVM: nVMX: don't load PDPTRS right after nested state set Maxim Levitsky
2021-02-17 17:52 ` Sean Christopherson
2021-02-17 18:06 ` Paolo Bonzini [this message]
2021-02-17 14:57 ` [PATCH 7/7] KVM: nSVM: call nested_svm_load_cr3 on nested state load Maxim Levitsky
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