From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
vkuznets@redhat.com, mlevitsk@redhat.com, dmatlack@google.com
Subject: Re: [PATCH 08/12] KVM: MMU: do not consult levels when freeing roots
Date: Fri, 11 Feb 2022 01:44:06 +0000 [thread overview]
Message-ID: <YgW/ZiURGlh5+nUr@google.com> (raw)
In-Reply-To: <YgW9bqM1M/zJEzqy@google.com>
On Fri, Feb 11, 2022, Sean Christopherson wrote:
> On Fri, Feb 11, 2022, Paolo Bonzini wrote:
> > On 2/11/22 01:54, Sean Christopherson wrote:
> > > > > @@ -3242,8 +3245,7 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> > > > > &invalid_list);
> > > > > if (free_active_root) {
> > > > > - if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL &&
> > > > > - (mmu->root_level >= PT64_ROOT_4LEVEL || mmu->direct_map)) {
> > > > > + if (to_shadow_page(mmu->root.hpa)) {
> > > > > mmu_free_root_page(kvm, &mmu->root.hpa, &invalid_list);
> > > > > } else if (mmu->pae_root) {
> > >
> > > Gah, this is technically wrong. It shouldn't truly matter, but it's wrong. root.hpa
> > > will not be backed by shadow page if the root is pml4_root or pml5_root, in which
> > > case freeing the PAE root is wrong. They should obviously be invalid already, but
> > > it's a little confusing because KVM wanders down a path that may not be relevant
> > > to the current mode.
> >
> > pml4_root and pml5_root are dummy, and the first "real" level of page tables
> > is stored in pae_root for that case too, so I think that should DTRT.
>
> Ugh, completely forgot that detail. You're correct. Probably worth a comment?
Actually, can't this be
if (to_shadow_page(mmu->root.hpa)) {
...
else if (!WARN_ON(!mmu->pae_root)) {
...
}
now that it's wrapped with VALID_PAGE(root.hpa)?
next prev parent reply other threads:[~2022-02-11 1:44 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-09 17:00 [PATCH 00/12] KVM: MMU: do not unload MMU roots on all role changes Paolo Bonzini
2022-02-09 17:00 ` [PATCH 01/12] KVM: x86: host-initiated EFER.LME write affects the MMU Paolo Bonzini
2022-02-10 22:49 ` Sean Christopherson
2022-02-09 17:00 ` [PATCH 02/12] KVM: MMU: move MMU role accessors to header Paolo Bonzini
2022-02-10 23:00 ` Sean Christopherson
2022-02-09 17:00 ` [PATCH 03/12] KVM: x86: do not deliver asynchronous page faults if CR0.PG=0 Paolo Bonzini
2022-02-10 23:10 ` Sean Christopherson
2022-02-10 23:14 ` Sean Christopherson
2022-02-10 23:16 ` Sean Christopherson
2022-02-11 11:16 ` Paolo Bonzini
2022-02-09 17:00 ` [PATCH 04/12] KVM: MMU: WARN if PAE roots linger after kvm_mmu_unload Paolo Bonzini
2022-02-10 23:20 ` Sean Christopherson
2022-02-11 11:18 ` Paolo Bonzini
2022-02-09 17:00 ` [PATCH 05/12] KVM: MMU: avoid NULL-pointer dereference on page freeing bugs Paolo Bonzini
2022-02-11 0:24 ` Sean Christopherson
2022-02-11 11:21 ` Paolo Bonzini
2022-02-09 17:00 ` [PATCH 06/12] KVM: MMU: rename kvm_mmu_reload Paolo Bonzini
2022-02-11 0:27 ` Sean Christopherson
2022-02-11 10:07 ` Paolo Bonzini
2022-02-11 16:16 ` Sean Christopherson
2022-02-11 16:52 ` Paolo Bonzini
2022-02-09 17:00 ` [PATCH 07/12] KVM: x86: use struct kvm_mmu_root_info for mmu->root Paolo Bonzini
2022-02-11 17:39 ` Sean Christopherson
2022-02-09 17:00 ` [PATCH 08/12] KVM: MMU: do not consult levels when freeing roots Paolo Bonzini
2022-02-11 0:41 ` Sean Christopherson
2022-02-11 0:54 ` Sean Christopherson
2022-02-11 1:07 ` Paolo Bonzini
2022-02-11 1:35 ` Sean Christopherson
2022-02-11 1:44 ` Sean Christopherson [this message]
2022-02-11 2:20 ` Sean Christopherson
2022-02-09 17:00 ` [PATCH 09/12] KVM: MMU: look for a cached PGD when going from 32-bit to 64-bit Paolo Bonzini
2022-02-11 1:32 ` Sean Christopherson
2022-02-11 1:37 ` Sean Christopherson
2022-02-11 10:09 ` Paolo Bonzini
2022-02-11 11:45 ` Paolo Bonzini
2022-02-11 17:38 ` Sean Christopherson
2022-02-09 17:00 ` [PATCH 10/12] KVM: MMU: load new PGD after the shadow MMU is initialized Paolo Bonzini
2022-02-11 17:45 ` Sean Christopherson
2022-02-11 17:47 ` Paolo Bonzini
2022-02-09 17:00 ` [PATCH 11/12] KVM: MMU: remove kvm_mmu_calc_root_page_role Paolo Bonzini
2022-02-11 17:53 ` Sean Christopherson
2022-02-09 17:00 ` [PATCH 12/12] KVM: x86: do not unload MMU roots on all role changes Paolo Bonzini
2022-02-11 9:08 ` Nikunj A. Dadhania
2022-02-11 18:48 ` Sean Christopherson
2022-02-14 16:34 ` Paolo Bonzini
2022-02-14 19:24 ` Sean Christopherson
2022-02-15 8:17 ` Paolo Bonzini
2022-02-09 17:07 ` [PATCH 00/12] KVM: MMU: " Sean Christopherson
2022-02-09 17:11 ` Paolo Bonzini
2022-02-09 17:16 ` Sean Christopherson
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