KVM: Don't set Accessed/Dirty bits for ZERO_PAGE

stable inclusion
from stable-v5.10.137
commit dceedbb5aba0bb7ecc2fca4390be5795840ea1b4
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I60PLB

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=dceedbb5aba0bb7ecc2fca4390be5795840ea1b4



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[ Upstream commit a1040b0d ]

Don't set Accessed/Dirty bits for a struct page with PG_reserved set,
i.e. don't set A/D bits for the ZERO_PAGE.  The ZERO_PAGE (or pages
depending on the architecture) should obviously never be written, and
similarly there's no point in marking it accessed as the page will never
be swapped out or reclaimed.  The comment in page-flags.h is quite clear
that PG_reserved pages should be managed only by their owner, and
strictly following that mandate also simplifies KVM's logic.

Fixes: 7df003c8 ("KVM: fix overflow of zero page refcount with ksm running")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220429010416.2788472-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>