Commit ba637018 authored by Quentin Perret's avatar Quentin Perret Committed by Marc Zyngier
Browse files

KVM: arm64: Fix pKVM page-tracking comments 



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now either slightly outdated or outright wrong.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: default avatarQuentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20250416152648.2982950-3-qperret@google.com


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 5db1bef9

arch/arm64/kvm/hyp/include/nvhe/memory.h

+19 −10
Original line number Diff line number Diff line
@@ -8,12 +8,16 @@ 
#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,
@@ -21,7 +25,12 @@ enum pkvm_page_state { 
	PKVM_PAGE_SHARED_BORROWED	= 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;