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KVM: arm64: Extend pkvm_page_state enumeration to handle absent pages

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Explicitly name the combination of SW0 | SW1 as reserved in the pte and
introduce a new PKVM_NOPAGE meta-state which, although not directly
stored in the software bits of the pte, can be used to represent an
entry for which there is no underlying page. This is distinct from an
invalid pte, as stage-2 identity mappings for the host are created
lazily and so an invalid pte there is the same as a valid mapping for
the purposes of ownership information.

This state will be used for permission checking during page transitions
in later patches.

Reviewed-by: Andrew Walbran <qwandor@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211215161232.1480836-9-qperret@google.com
This commit is contained in:
Will Deacon 2021-12-15 16:12:25 +00:00 committed by Marc Zyngier
parent a83e2191b7
commit 3d467f7b8c
1 changed files with 5 additions and 0 deletions
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5
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
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@ -24,6 +24,11 @@ enum pkvm_page_state {
PKVM_PAGE_OWNED = 0ULL,
PKVM_PAGE_SHARED_OWNED = KVM_PGTABLE_PROT_SW0,
PKVM_PAGE_SHARED_BORROWED = KVM_PGTABLE_PROT_SW1,
__PKVM_PAGE_RESERVED = KVM_PGTABLE_PROT_SW0 |
KVM_PGTABLE_PROT_SW1,
/* Meta-states which aren't encoded directly in the PTE's SW bits */
PKVM_NOPAGE,
};
#define PKVM_PAGE_STATE_PROT_MASK (KVM_PGTABLE_PROT_SW0 | KVM_PGTABLE_PROT_SW1)