linux-kernel - [PATCH 0/4] KVM: x86/mmu: Zap invalid TDP MMU roots when unmapping

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20211215011557.399940-1-seanjc@google.com>
Date:   Wed, 15 Dec 2021 01:15:53 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Ben Gardon <bgardon@...gle.com>
Subject: [PATCH 0/4] KVM: x86/mmu: Zap invalid TDP MMU roots when unmapping

Patches 01-03 implement a bug fix by ensuring KVM zaps both valid and
invalid roots when unmapping a gfn range (including the magic "all" range).
Failure to zap invalid roots means KVM doesn't honor the mmu_notifier's
requirement that all references are dropped.

set_nx_huge_pages() is the most blatant offender, as it doesn't elevate
mm_users and so a VM's entire mm can be released, but the same underlying
bug exists for any "unmap" command from the mmu_notifier in combination
with a memslot update.  E.g. if KVM is deleting a memslot, and a
mmu_notifier hook acquires mmu_lock while it's dropped by
kvm_mmu_zap_all_fast(), the mmu_notifier hook will see the to-be-deleted
memslot but won't zap entries from the invalid roots.

Patch 04 is cleanup to reuse the common iterator for walking _only_
invalid roots.

Sean Christopherson (4):
  KVM: x86/mmu: Use common TDP MMU zap helper for MMU notifier unmap
    hook
  KVM: x86/mmu: Move "invalid" check out of kvm_tdp_mmu_get_root()
  KVM: x86/mmu: Zap _all_ roots when unmapping gfn range in TDP MMU
  KVM: x86/mmu: Use common iterator for walking invalid TDP MMU roots

 arch/x86/kvm/mmu/tdp_mmu.c | 116 +++++++++++++++++--------------------
 arch/x86/kvm/mmu/tdp_mmu.h |   3 -
 2 files changed, 53 insertions(+), 66 deletions(-)

-- 
2.34.1.173.g76aa8bc2d0-goog