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/* SPDX-License-Identifier: GPL-2.0-or-later */
#include <xen/mm.h>
#include <xen/pmap.h>
#include <xen/vmap.h>
/* Override macros from asm/page.h to make them work with mfn_t */
#undef virt_to_mfn
#define virt_to_mfn(va) _mfn(__virt_to_mfn(va))
/* cpu0's domheap page tables */
static DEFINE_PAGE_TABLES(cpu0_dommap, DOMHEAP_SECOND_PAGES);
/*
* xen_dommap == pages used by map_domain_page, these pages contain
* the second level pagetables which map the domheap region
* starting at DOMHEAP_VIRT_START in 2MB chunks.
*/
static DEFINE_PER_CPU(lpae_t *, xen_dommap);
/*
* Prepare the area that will be used to map domheap pages. They are
* mapped in 2MB chunks, so we need to allocate the page-tables up to
* the 2nd level.
*
* The caller should make sure the root page-table for @cpu has been
* allocated.
*/
bool init_domheap_mappings(unsigned int cpu)
{
unsigned int order = get_order_from_pages(DOMHEAP_SECOND_PAGES);
lpae_t *root = per_cpu(xen_pgtable, cpu);
unsigned int i, first_idx;
lpae_t *domheap;
mfn_t mfn;
ASSERT(root);
ASSERT(!per_cpu(xen_dommap, cpu));
/*
* The domheap for cpu0 is initialized before the heap is initialized.
* So we need to use pre-allocated pages.
*/
if ( !cpu )
domheap = cpu0_dommap;
else
domheap = alloc_xenheap_pages(order, 0);
if ( !domheap )
return false;
/* Ensure the domheap has no stray mappings */
memset(domheap, 0, DOMHEAP_SECOND_PAGES * PAGE_SIZE);
/*
* Update the first level mapping to reference the local CPUs
* domheap mapping pages.
*/
mfn = virt_to_mfn(domheap);
first_idx = first_table_offset(DOMHEAP_VIRT_START);
for ( i = 0; i < DOMHEAP_SECOND_PAGES; i++ )
{
lpae_t pte = mfn_to_xen_entry(mfn_add(mfn, i), MT_NORMAL);
pte.pt.table = 1;
write_pte(&root[first_idx + i], pte);
}
per_cpu(xen_dommap, cpu) = domheap;
return true;
}
void *map_domain_page_global(mfn_t mfn)
{
return vmap(&mfn, 1);
}
void unmap_domain_page_global(const void *va)
{
vunmap(va);
}
/* Map a page of domheap memory */
void *map_domain_page(mfn_t mfn)
{
unsigned long flags;
lpae_t *map = this_cpu(xen_dommap);
unsigned long slot_mfn = mfn_x(mfn) & ~XEN_PT_LPAE_ENTRY_MASK;
vaddr_t va;
lpae_t pte;
int i, slot;
local_irq_save(flags);
/* The map is laid out as an open-addressed hash table where each
* entry is a 2MB superpage pte. We use the available bits of each
* PTE as a reference count; when the refcount is zero the slot can
* be reused. */
for ( slot = (slot_mfn >> XEN_PT_LPAE_SHIFT) % DOMHEAP_ENTRIES, i = 0;
i < DOMHEAP_ENTRIES;
slot = (slot + 1) % DOMHEAP_ENTRIES, i++ )
{
if ( map[slot].pt.avail < 0xf &&
map[slot].pt.base == slot_mfn &&
map[slot].pt.valid )
{
/* This slot already points to the right place; reuse it */
map[slot].pt.avail++;
break;
}
else if ( map[slot].pt.avail == 0 )
{
/* Commandeer this 2MB slot */
pte = mfn_to_xen_entry(_mfn(slot_mfn), MT_NORMAL);
pte.pt.avail = 1;
write_pte(map + slot, pte);
break;
}
}
/* If the map fills up, the callers have misbehaved. */
BUG_ON(i == DOMHEAP_ENTRIES);
#ifndef NDEBUG
/* Searching the hash could get slow if the map starts filling up.
* Cross that bridge when we come to it */
{
static int max_tries = 32;
if ( i >= max_tries )
{
dprintk(XENLOG_WARNING, "Domheap map is filling: %i tries\n", i);
max_tries *= 2;
}
}
#endif
local_irq_restore(flags);
va = (DOMHEAP_VIRT_START
+ (slot << SECOND_SHIFT)
+ ((mfn_x(mfn) & XEN_PT_LPAE_ENTRY_MASK) << THIRD_SHIFT));
/*
* We may not have flushed this specific subpage at map time,
* since we only flush the 4k page not the superpage
*/
flush_xen_tlb_range_va_local(va, PAGE_SIZE);
return (void *)va;
}
/* Release a mapping taken with map_domain_page() */
void unmap_domain_page(const void *va)
{
unsigned long flags;
lpae_t *map = this_cpu(xen_dommap);
int slot = ((unsigned long) va - DOMHEAP_VIRT_START) >> SECOND_SHIFT;
if ( !va )
return;
local_irq_save(flags);
ASSERT(slot >= 0 && slot < DOMHEAP_ENTRIES);
ASSERT(map[slot].pt.avail != 0);
map[slot].pt.avail--;
local_irq_restore(flags);
}
mfn_t domain_page_map_to_mfn(const void *ptr)
{
unsigned long va = (unsigned long)ptr;
lpae_t *map = this_cpu(xen_dommap);
int slot = (va - DOMHEAP_VIRT_START) >> SECOND_SHIFT;
unsigned long offset = (va>>THIRD_SHIFT) & XEN_PT_LPAE_ENTRY_MASK;
if ( (va >= VMAP_VIRT_START) && ((va - VMAP_VIRT_START) < VMAP_VIRT_SIZE) )
return virt_to_mfn(va);
ASSERT(slot >= 0 && slot < DOMHEAP_ENTRIES);
ASSERT(map[slot].pt.avail != 0);
return mfn_add(lpae_get_mfn(map[slot]), offset);
}
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* indent-tabs-mode: nil
* End:
*/
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