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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Message-ID: <CA+res+RQbK2wCWtfV4bNBF3GKYqRjPOAPDfWa_+6Zjqi--p8aw@mail.gmail.com>
Date:   Fri, 6 Dec 2019 09:54:35 +0100
From:   Jack Wang <jack.wang.usish@...il.com>
To:     Jack Wang <jack.wang.usish@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        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()

Dan Rue <dan.rue@...aro.org> 于2019年12月5日周四 下午9:52写道：
>
> On Thu, Dec 05, 2019 at 10:51:18AM +0100, Jack Wang wrote:
> > Dan Rue <dan.rue@...aro.org> 于2019年12月4日周三 下午6:50写道：
> > >
> > > On Mon, Dec 02, 2019 at 03:40:04PM +0100, Jack Wang wrote:
> > > > 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:
> > >
> > > Hi Jack - can you be more specific about the failing tests? What type of
> > > environment and which tests failed, which version of kvm-unit-tests? Do
> > > you have any logs available? I ask because we do run kvm-unit-tests on
> > > x86 and arm64 but we did not see these regressions.
> > >
> > > Thanks,
> > > Dan
> > >
> > Hi Dan,
> >
> > I'm running at kvm-unit-tests commit b1414c5f0142 ("x86: vmx: fix
> > required alignment for posted interrupt descriptor")
> >
> > using "run_tests.sh -a -t -j8" with qemu-2.7.1
> >
> > Left side has only 78 tests ok, and right side has 112 tests ok.
>
> Thanks - so we run it with "run_tests.sh -v" and only see 43 passes in
> the best case. Besides missing -a, we see a skip for the vmx related
> tests because vmx isn't enabled in our environment.
>
> We will fix those problems in LKFT so that we can catch regressions like
> this before they are released.
>
> Dan
Sounds good.

Thanks,
Jack