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Date: Mon, 24 Aug 2020 17:09:20 -0700 From: Sean Christopherson <sean.j.christopherson@...el.com> To: Jim Mattson <jmattson@...gle.com> Cc: Vitaly Kuznetsov <vkuznets@...hat.com>, Paolo Bonzini <pbonzini@...hat.com>, Wanpeng Li <wanpengli@...cent.com>, kvm list <kvm@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] KVM: VMX: fix crash cleanup when KVM wasn't used On Mon, Aug 24, 2020 at 03:45:26PM -0700, Jim Mattson wrote: > On Mon, Aug 24, 2020 at 11:57 AM Jim Mattson <jmattson@...gle.com> wrote: > > > > On Fri, Aug 21, 2020 at 8:40 PM Sean Christopherson > > <sean.j.christopherson@...el.com> wrote: > > > I agree the code is a mess (kvm_init() and kvm_exit() included), but I'm > > > pretty sure hardware_disable_nolock() is guaranteed to be a nop as it's > > > impossible for kvm_usage_count to be non-zero if vmx_init() hasn't > > > finished. > > > > Unless I'm missing something, there's no check for a non-zero > > kvm_usage_count on this path. There is such a check in > > hardware_disable_all_nolock(), but not in hardware_disable_nolock(). > > However, cpus_hardware_enabled shouldn't have any bits set, so > everything's fine. Nothing to see here, after all. Ugh, I forgot that hardware_disable_all_nolock() does a BUG_ON() instead of bailing on !kvm_usage_count.
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