/*
* Allocate new pmd(s). It is checked whether the old pmd is still in place.
* If not, nothing is changed. This is okay as the only reason for allocating
* a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual
* pmd. In case of PAE/x86-32 there are multiple pmds to allocate!
*/
static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
{
pte_t *ptechk;
pte_t *pte_newpg[PMDS_PER_MID_PAGE];
pmd_t *pmdp;
unsigned int level;
unsigned long flags;
unsigned long vaddr;
int i;
/* Do all allocations first to bail out in error case. */
for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
pte_newpg[i] = alloc_p2m_page();
if (!pte_newpg[i]) {
for (i--; i >= 0; i--)
free_p2m_page(pte_newpg[i]);
return NULL;
}
}
vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1);
for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
copy_page(pte_newpg[i], pte_pg);
paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT);
pmdp = lookup_pmd_address(vaddr);
BUG_ON(!pmdp);
spin_lock_irqsave(&p2m_update_lock, flags);
ptechk = lookup_address(vaddr, &level);
if (ptechk == pte_pg) {
HYPERVISOR_shared_info->arch.p2m_generation++;
wmb(); /* Tools are synchronizing via p2m_generation. */
set_pmd(pmdp,
__pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE));
wmb(); /* Tools are synchronizing via p2m_generation. */
HYPERVISOR_shared_info->arch.p2m_generation++;
pte_newpg[i] = NULL;
}
spin_unlock_irqrestore(&p2m_update_lock, flags);
if (pte_newpg[i]) {
paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT);
free_p2m_page(pte_newpg[i]);
}
vaddr += PMD_SIZE;
}
return lookup_address(addr, &level);
}
/*
* Fully allocate the p2m structure for a given pfn. We need to check
* that both the top and mid levels are allocated, and make sure the
* parallel mfn tree is kept in sync. We may race with other cpus, so
* the new pages are installed with cmpxchg; if we lose the race then
* simply free the page we allocated and use the one that's there.
*/
static bool alloc_p2m(unsigned long pfn)
{
unsigned topidx;
unsigned long *top_mfn_p, *mid_mfn;
pte_t *ptep, *pte_pg;
unsigned int level;
unsigned long flags;
unsigned long addr = (unsigned long)(xen_p2m_addr + pfn);
unsigned long p2m_pfn;
ptep = lookup_address(addr, &level);
BUG_ON(!ptep || level != PG_LEVEL_4K);
pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) {
/* PMD level is missing, allocate a new one */
ptep = alloc_p2m_pmd(addr, pte_pg);
if (!ptep)
return false;
}
if (p2m_top_mfn && pfn < MAX_P2M_PFN) {
topidx = p2m_top_index(pfn);
top_mfn_p = &p2m_top_mfn[topidx];
mid_mfn = ACCESS_ONCE(p2m_top_mfn_p[topidx]);
BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
if (mid_mfn == p2m_mid_missing_mfn) {
/* Separately check the mid mfn level */
unsigned long missing_mfn;
unsigned long mid_mfn_mfn;
unsigned long old_mfn;
mid_mfn = alloc_p2m_page();
if (!mid_mfn)
return false;
p2m_mid_mfn_init(mid_mfn, p2m_missing);
missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
mid_mfn_mfn = virt_to_mfn(mid_mfn);
old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn);
if (old_mfn != missing_mfn) {
free_p2m_page(mid_mfn);
mid_mfn = mfn_to_virt(old_mfn);
} else {
p2m_top_mfn_p[topidx] = mid_mfn;
}
}
} else {
mid_mfn = NULL;
}
p2m_pfn = pte_pfn(READ_ONCE(*ptep));
if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) ||
p2m_pfn == PFN_DOWN(__pa(p2m_missing))) {
/* p2m leaf page is missing */
unsigned long *p2m;
p2m = alloc_p2m_page();
if (!p2m)
return false;
if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
p2m_init(p2m);
else
p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1));
spin_lock_irqsave(&p2m_update_lock, flags);
if (pte_pfn(*ptep) == p2m_pfn) {
HYPERVISOR_shared_info->arch.p2m_generation++;
wmb(); /* Tools are synchronizing via p2m_generation. */
set_pte(ptep,
pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL));
wmb(); /* Tools are synchronizing via p2m_generation. */
HYPERVISOR_shared_info->arch.p2m_generation++;
if (mid_mfn)
mid_mfn[p2m_mid_index(pfn)] = virt_to_mfn(p2m);
p2m = NULL;
}
spin_unlock_irqrestore(&p2m_update_lock, flags);
if (p2m)
free_p2m_page(p2m);
}
/* Expanded the p2m? */
if (pfn > xen_p2m_last_pfn) {
xen_p2m_last_pfn = pfn;
HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn;
}
return true;
}
/*
* Fully allocate the p2m structure for a given pfn. We need to check
* that both the top and mid levels are allocated, and make sure the
* parallel mfn tree is kept in sync. We may race with other cpus, so
* the new pages are installed with cmpxchg; if we lose the race then
* simply free the page we allocated and use the one that's there.
*/
static bool alloc_p2m(unsigned long pfn)
{
unsigned topidx, mididx;
unsigned long ***top_p, **mid;
unsigned long *top_mfn_p, *mid_mfn;
topidx = p2m_top_index(pfn);
mididx = p2m_mid_index(pfn);
top_p = &p2m_top[topidx];
mid = *top_p;
if (mid == p2m_mid_missing) {
/* Mid level is missing, allocate a new one */
mid = alloc_p2m_page();
if (!mid)
return false;
p2m_mid_init(mid);
if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing)
free_p2m_page(mid);
}
top_mfn_p = &p2m_top_mfn[topidx];
mid_mfn = p2m_top_mfn_p[topidx];
BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
if (mid_mfn == p2m_mid_missing_mfn) {
/* Separately check the mid mfn level */
unsigned long missing_mfn;
unsigned long mid_mfn_mfn;
mid_mfn = alloc_p2m_page();
if (!mid_mfn)
return false;
p2m_mid_mfn_init(mid_mfn);
missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
mid_mfn_mfn = virt_to_mfn(mid_mfn);
if (cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn) != missing_mfn)
free_p2m_page(mid_mfn);
else
p2m_top_mfn_p[topidx] = mid_mfn;
}
if (p2m_top[topidx][mididx] == p2m_identity ||
p2m_top[topidx][mididx] == p2m_missing) {
/* p2m leaf page is missing */
unsigned long *p2m;
unsigned long *p2m_orig = p2m_top[topidx][mididx];
p2m = alloc_p2m_page();
if (!p2m)
return false;
p2m_init(p2m);
if (cmpxchg(&mid[mididx], p2m_orig, p2m) != p2m_orig)
free_p2m_page(p2m);
else
mid_mfn[mididx] = virt_to_mfn(p2m);
}
return true;
}
