eabc7aaef7
When the handling of a guest stage-2 permission fault races with an MMU notifier, the faulting page might be gone from the guest's stage-2 by the point we attempt to call (p)kvm_pgtable_stage2_relax_perms(). In the normal KVM case, this leads to returning -EAGAIN which user_mem_abort() handles correctly by simply re-entering the guest. However, the pKVM hypercall implementation has additional logic to check the page state using __check_host_shared_guest() which gets confused with absence of a page mapped at the requested IPA and returns -ENOENT, hence breaking user_mem_abort() and hilarity ensues. Luckily, several of the hypercalls for managing the stage-2 page-table of NP guests have no effect on the pKVM ownership tracking (wrprotect, test_clear_young, mkyoung, and crucially relax_perms), so the extra state checking logic is in fact not strictly necessary. So, to fix the discrepancy between standard KVM and pKVM, let's just drop the superfluous __check_host_shared_guest() logic from those hypercalls and make the extra state checking a debug assertion dependent on CONFIG_NVHE_EL2_DEBUG as we already do for other transitions. Signed-off-by: Quentin Perret <qperret@google.com> Reviewed-by: Oliver Upton <oliver.upton@linux.dev> Link: https://lore.kernel.org/r/20250207145438.1333475-3-qperret@google.com Signed-off-by: Marc Zyngier <maz@kernel.org> |
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