KVM: x86: Fix handling of APIC LVT updates when userspace changes MCG_CAP

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Add a helper to update KVM's in-kernel local APIC in response to MCG_CAP
being changed by userspace to fix multiple bugs.  First and foremost,
KVM needs to check that there's an in-kernel APIC prior to dereferencing
vcpu->arch.apic.  Beyond that, any "new" LVT entries need to be masked,
and the APIC version register needs to be updated as it reports out the
number of LVT entries.

Fixes: 4b903561ec ("KVM: x86: Add Corrected Machine Check Interrupt (CMCI) emulation to lapic.")
Reported-by: syzbot+8cdad6430c24f396f158@syzkaller.appspotmail.com
Cc: Siddh Raman Pant <code@siddh.me>
Cc: Jue Wang <juew@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>

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This commit is contained in:

Sean Christopherson 2022-07-08 15:48:10 -07:00

parent 03d84f9689

commit f83894b24c

3 changed files with 22 additions and 2 deletions

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19

arch/x86/kvm/lapic.c

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1

arch/x86/kvm/lapic.h

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4

arch/x86/kvm/x86.c

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