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KVM: arm64: Fix pKVM page-tracking comments

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Most of the comments relating to pKVM page-tracking in nvhe/memory.h are
now either slightly outdated or outright wrong. Fix the comments.

Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20250416152648.2982950-3-qperret@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Quentin Perret
2025-04-16 15:26:42 +00:00
committed by Marc Zyngier
parent 5db1bef933
commit ba637018ca
1 changed files with 18 additions and 9 deletions
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27
arch/arm64/kvm/hyp/include/nvhe/memory.h
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@@ -8,20 +8,29 @@
#include <linux/types.h>
/*
* Bits 0-1 are reserved to track the memory ownership state of each page:
* 00: The page is owned exclusively by the page-table owner.
* 01: The page is owned by the page-table owner, but is shared
* with another entity.
* 10: The page is shared with, but not owned by the page-table owner.
* 11: Reserved for future use (lending).
* Bits 0-1 are used to encode the memory ownership state of each page from the
* point of view of a pKVM "component" (host, hyp, guest, ... see enum
* pkvm_component_id):
* 00: The page is owned and exclusively accessible by the component;
* 01: The page is owned and accessible by the component, but is also
* accessible by another component;
* 10: The page is accessible but not owned by the component;
* The storage of this state depends on the component: either in the
* hyp_vmemmap for the host state or in PTE software bits for the hypervisor
* and guests.
*/
enum pkvm_page_state {
PKVM_PAGE_OWNED = 0ULL,
PKVM_PAGE_SHARED_OWNED = BIT(0),
PKVM_PAGE_SHARED_BORROWED = BIT(1),
__PKVM_PAGE_RESERVED = BIT(0) | BIT(1),
__PKVM_PAGE_RESERVED = BIT(0) | BIT(1),
/* Meta-states which aren't encoded directly in the PTE's SW bits */
/*
* 'Meta-states' are not stored directly in PTE SW bits for hyp and
* guest states, but inferred from the context (e.g. invalid PTE
* entries). For the host, meta-states are stored directly in the
* struct hyp_page.
*/
PKVM_NOPAGE = BIT(2),
};
#define PKVM_PAGE_META_STATES_MASK (~__PKVM_PAGE_RESERVED)
@@ -44,7 +53,7 @@ struct hyp_page {
u16 refcount;
u8 order;
/* Host (non-meta) state. Guarded by the host stage-2 lock. */
/* Host state. Guarded by the host stage-2 lock. */
enum pkvm_page_state host_state : 8;
u32 host_share_guest_count;