linux-kernel - Re: [PATCH 4.19 067/306] KVM: nVMX: move check_vmentry_postreqs() call to nested_vmx_enter_non_root

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Date:   Mon, 2 Dec 2019 15:40:04 +0100
From:   Jack Wang <jack.wang.usish@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable <stable@...r.kernel.org>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Jim Mattson <jmattson@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.19 067/306] KVM: nVMX: move check_vmentry_postreqs()
 call to nested_vmx_enter_non_root_mode()

Greg Kroah-Hartman <gregkh@...uxfoundation.org> 于2019年11月27日周三 下午10:30写道：
>
> From: Sean Christopherson <sean.j.christopherson@...el.com>
>
> [ Upstream commit 7671ce21b13b9596163a29f4712cb2451a9b97dc ]
>
> In preparation of supporting checkpoint/restore for nested state,
> commit ca0bde28f2ed ("kvm: nVMX: Split VMCS checks from nested_vmx_run()")
> modified check_vmentry_postreqs() to only perform the guest EFER
> consistency checks when nested_run_pending is true.  But, in the
> normal nested VMEntry flow, nested_run_pending is only set after
> check_vmentry_postreqs(), i.e. the consistency check is being skipped.
>
> Alternatively, nested_run_pending could be set prior to calling
> check_vmentry_postreqs() in nested_vmx_run(), but placing the
> consistency checks in nested_vmx_enter_non_root_mode() allows us
> to split prepare_vmcs02() and interleave the preparation with
> the consistency checks without having to change the call sites
> of nested_vmx_enter_non_root_mode().  In other words, the rest
> of the consistency check code in nested_vmx_run() will be joining
> the postreqs checks in future patches.
>
> Fixes: ca0bde28f2ed ("kvm: nVMX: Split VMCS checks from nested_vmx_run()")
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Cc: Jim Mattson <jmattson@...gle.com>
> Reviewed-by: Jim Mattson <jmattson@...gle.com>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  arch/x86/kvm/vmx.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index fe7fdd666f091..bdf019f322117 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -12694,6 +12694,9 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu, u32 *exit_qual)
>         if (likely(!evaluate_pending_interrupts) && kvm_vcpu_apicv_active(vcpu))
>                 evaluate_pending_interrupts |= vmx_has_apicv_interrupt(vcpu);
>
> +       if (from_vmentry && check_vmentry_postreqs(vcpu, vmcs12, exit_qual))
> +               return EXIT_REASON_INVALID_STATE;
> +
>         enter_guest_mode(vcpu);
>
>         if (!(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS))
> @@ -12836,13 +12839,6 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
>          */
>         skip_emulated_instruction(vcpu);
>
> -       ret = check_vmentry_postreqs(vcpu, vmcs12, &exit_qual);
> -       if (ret) {
> -               nested_vmx_entry_failure(vcpu, vmcs12,
> -                                        EXIT_REASON_INVALID_STATE, exit_qual);
> -               return 1;
> -       }
> -
>         /*
>          * We're finally done with prerequisite checking, and can start with
>          * the nested entry.
> --
> 2.20.1
>
>
>
Hi all,

This commit caused many kvm-unit-tests regression, cherry-pick
following commits from 4.20 fix the regression:
d63907dc7dd1 ("KVM: nVMX: rename enter_vmx_non_root_mode to
nested_vmx_enter_non_root_mode")
a633e41e7362 ("KVM: nVMX: assimilate nested_vmx_entry_failure() into
nested_vmx_enter_non_root_mode()")

Regards,
Jack Wang
1 & 1 IONOS SE