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alistair23-linux/virt
Lai Jiangshan a5c7a45668 kvm: check tlbs_dirty directly
commit 88bf56d04b upstream.

In kvm_mmu_notifier_invalidate_range_start(), tlbs_dirty is used as:
        need_tlb_flush |= kvm->tlbs_dirty;
with need_tlb_flush's type being int and tlbs_dirty's type being long.

It means that tlbs_dirty is always used as int and the higher 32 bits
is useless.  We need to check tlbs_dirty in a correct way and this
change checks it directly without propagating it to need_tlb_flush.

Note: it's _extremely_ unlikely this neglecting of higher 32 bits can
cause problems in practice.  It would require encountering tlbs_dirty
on a 4 billion count boundary, and KVM would need to be using shadow
paging or be running a nested guest.

Cc: stable@vger.kernel.org
Fixes: a4ee1ca4a3 ("KVM: MMU: delay flush all tlbs on sync_page path")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20201217154118.16497-1-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-12 20:16:22 +01:00
..
kvm kvm: check tlbs_dirty directly 2021-01-12 20:16:22 +01:00
lib treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00