KVM: x86: Reset IRTE to host control if *new* route isn't postable

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commit 9bcac97dc4 upstream.

Restore an IRTE back to host control (remapped or posted MSI mode) if the
*new* GSI route prevents posting the IRQ directly to a vCPU, regardless of
the GSI routing type.  Updating the IRTE if and only if the new GSI is an
MSI results in KVM leaving an IRTE posting to a vCPU.

The dangling IRTE can result in interrupts being incorrectly delivered to
the guest, and in the worst case scenario can result in use-after-free,
e.g. if the VM is torn down, but the underlying host IRQ isn't freed.

Fixes: efc644048e ("KVM: x86: Update IRTE for posted-interrupts")
Fixes: 411b44ba80 ("svm: Implements update_pi_irte hook to setup posted interrupt")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20250404193923.1413163-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Sean Christopherson 2025-04-04 12:38:17 -07:00 • committed by Greg Kroah-Hartman

parent a22fe6f843

commit b5de7ac74f

2 changed files with 41 additions and 45 deletions

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58

arch/x86/kvm/svm/avic.c

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28

arch/x86/kvm/vmx/posted_intr.c

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