memory.h

/* SPDX-License-Identifier: GPL-2.0-only */
#ifndef __KVM_HYP_MEMORY_H
#define __KVM_HYP_MEMORY_H

#include <asm/kvm_mmu.h>
#include <asm/page.h>

#include <linux/types.h>

/*
 * 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 and hyp states or in PTE software bits for guests.
 */
enum pkvm_page_state {
	PKVM_PAGE_OWNED			= 0ULL,
	PKVM_PAGE_SHARED_OWNED		= BIT(0),
	PKVM_PAGE_SHARED_BORROWED	= BIT(1),

	/*
	 * 'Meta-states' are not stored directly in PTE SW bits for guest
	 * states, but inferred from the context (e.g. invalid PTE entries).
	 * For the host and hyp, meta-states are stored directly in the
	 * struct hyp_page.
	 */
	PKVM_NOPAGE			= BIT(0) | BIT(1),
};
#define PKVM_PAGE_STATE_MASK		(BIT(0) | BIT(1))

#define PKVM_PAGE_STATE_PROT_MASK	(KVM_PGTABLE_PROT_SW0 | KVM_PGTABLE_PROT_SW1)
static inline enum kvm_pgtable_prot pkvm_mkstate(enum kvm_pgtable_prot prot,
						 enum pkvm_page_state state)
{
	prot &= ~PKVM_PAGE_STATE_PROT_MASK;
	prot |= FIELD_PREP(PKVM_PAGE_STATE_PROT_MASK, state);
	return prot;
}

static inline enum pkvm_page_state pkvm_getstate(enum kvm_pgtable_prot prot)
{
	return FIELD_GET(PKVM_PAGE_STATE_PROT_MASK, prot);
}

struct hyp_page {
	u16 refcount;
	u8 order;

	/* Host state. Guarded by the host stage-2 lock. */
	unsigned __host_state : 4;

	/*
	 * Complement of the hyp state. Guarded by the hyp stage-1 lock. We use
	 * the complement so that the initial 0 in __hyp_state_comp (due to the
	 * entire vmemmap starting off zeroed) encodes PKVM_NOPAGE.
	 */
	unsigned __hyp_state_comp : 4;

	u32 host_share_guest_count;
};

extern u64 __hyp_vmemmap;
#define hyp_vmemmap ((struct hyp_page *)__hyp_vmemmap)

#define __hyp_va(phys)	((void *)((phys_addr_t)(phys) - hyp_physvirt_offset))

static inline void *hyp_phys_to_virt(phys_addr_t phys)
{
	return __hyp_va(phys);
}

static inline phys_addr_t hyp_virt_to_phys(void *addr)
{
	return __hyp_pa(addr);
}

#define hyp_phys_to_pfn(phys)	((phys) >> PAGE_SHIFT)
#define hyp_pfn_to_phys(pfn)	((phys_addr_t)((pfn) << PAGE_SHIFT))

static inline struct hyp_page *hyp_phys_to_page(phys_addr_t phys)
{
	BUILD_BUG_ON(sizeof(struct hyp_page) != sizeof(u64));
	return &hyp_vmemmap[hyp_phys_to_pfn(phys)];
}

#define hyp_virt_to_page(virt)	hyp_phys_to_page(__hyp_pa(virt))
#define hyp_virt_to_pfn(virt)	hyp_phys_to_pfn(__hyp_pa(virt))

#define hyp_page_to_pfn(page)	((struct hyp_page *)(page) - hyp_vmemmap)
#define hyp_page_to_phys(page)  hyp_pfn_to_phys((hyp_page_to_pfn(page)))
#define hyp_page_to_virt(page)	__hyp_va(hyp_page_to_phys(page))
#define hyp_page_to_pool(page)	(((struct hyp_page *)page)->pool)

static inline enum pkvm_page_state get_host_state(struct hyp_page *p)
{
	return p->__host_state;
}

static inline void set_host_state(struct hyp_page *p, enum pkvm_page_state state)
{
	p->__host_state = state;
}

static inline enum pkvm_page_state get_hyp_state(struct hyp_page *p)
{
	return p->__hyp_state_comp ^ PKVM_PAGE_STATE_MASK;
}

static inline void set_hyp_state(struct hyp_page *p, enum pkvm_page_state state)
{
	p->__hyp_state_comp = state ^ PKVM_PAGE_STATE_MASK;
}

/*
 * Refcounting for 'struct hyp_page'.
 * hyp_pool::lock must be held if atomic access to the refcount is required.
 */
static inline int hyp_page_count(void *addr)
{
	struct hyp_page *p = hyp_virt_to_page(addr);

	return p->refcount;
}

static inline void hyp_page_ref_inc(struct hyp_page *p)
{
	BUG_ON(p->refcount == USHRT_MAX);
	p->refcount++;
}

static inline void hyp_page_ref_dec(struct hyp_page *p)
{
	BUG_ON(!p->refcount);
	p->refcount--;
}

static inline int hyp_page_ref_dec_and_test(struct hyp_page *p)
{
	hyp_page_ref_dec(p);
	return (p->refcount == 0);
}

static inline void hyp_set_page_refcounted(struct hyp_page *p)
{
	BUG_ON(p->refcount);
	p->refcount = 1;
}
#endif /* __KVM_HYP_MEMORY_H */