KVM: x86/mmu: WARN on NULL pae_root or lm_root, or bad shadow root level

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WARN if KVM is about to dereference a NULL pae_root or lm_root when
loading an MMU, and convert the BUG() on a bad shadow_root_level into a
WARN (now that errors are handled cleanly).  With nested NPT, botching
the level and sending KVM down the wrong path is all too easy, and the
on-demand allocation of pae_root and lm_root means bugs crash the host.
Obviously, KVM could unconditionally allocate the roots, but that's
arguably a worse failure mode as it would potentially corrupt the guest
instead of crashing it.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210305011101.3597423-18-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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Sean Christopherson 2021-03-04 17:11:01 -08:00 • committed by Paolo Bonzini

parent a91f387b4b

commit 73ad160693

1 changed files with 13 additions and 2 deletions

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arch/x86/kvm/mmu/mmu.c

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