FROMLIST: KVM: arm64: Extend pkvm_page_state enumeration to handle absent pages

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.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20211201170411.1561936-10-qperret@google.com
Bug: 209599700
Change-Id: I7f31f675d39c5b33168eb652ca35822fba2ec0ff
This commit is contained in:
Will Deacon
2021-12-01 17:04:03 +00:00
committed by Quentin Perret
parent e41cc0f83a
commit 1d5d8f2493

View File

@@ -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)