KVM: x86: Disallow hugepages when memory attributes are mixed

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Disallow creating hugepages with mixed memory attributes, e.g. shared
versus private, as mapping a hugepage in this case would allow the guest
to access memory with the wrong attributes, e.g. overlaying private memory
with a shared hugepage.

Tracking whether or not attributes are mixed via the existing
disallow_lpage field, but use the most significant bit in 'disallow_lpage'
to indicate a hugepage has mixed attributes instead using the normal
refcounting.  Whether or not attributes are mixed is binary; either they
are or they aren't.  Attempting to squeeze that info into the refcount is
unnecessarily complex as it would require knowing the previous state of
the mixed count when updating attributes.  Using a flag means KVM just
needs to ensure the current status is reflected in the memslots.

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20231027182217.3615211-20-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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This commit is contained in:

Chao Peng 2023-10-27 11:22:01 -07:00 • committed by Paolo Bonzini

parent ee605e3156

commit 90b4fe1798

3 changed files with 159 additions and 2 deletions

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3

arch/x86/include/asm/kvm_host.h

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154

arch/x86/kvm/mmu/mmu.c

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4

arch/x86/kvm/x86.c

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