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Diffstat (limited to 'arch/x86/xen/p2m.c')
-rw-r--r--arch/x86/xen/p2m.c122
1 files changed, 103 insertions, 19 deletions
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index b2e91d4..72213da 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -196,9 +196,11 @@ RESERVE_BRK(p2m_mid_identity, PAGE_SIZE * 2 * 3);
/* When we populate back during bootup, the amount of pages can vary. The
* max we have is seen is 395979, but that does not mean it can't be more.
- * But some machines can have 3GB I/O holes even. So lets reserve enough
- * for 4GB of I/O and E820 holes. */
-RESERVE_BRK(p2m_populated, PMD_SIZE * 4);
+ * Some machines can have 3GB I/O holes even. With early_can_reuse_p2m_middle
+ * it can re-use Xen provided mfn_list array, so we only need to allocate at
+ * most three P2M top nodes. */
+RESERVE_BRK(p2m_populated, PAGE_SIZE * 3);
+
static inline unsigned p2m_top_index(unsigned long pfn)
{
BUG_ON(pfn >= MAX_P2M_PFN);
@@ -575,12 +577,99 @@ static bool __init early_alloc_p2m(unsigned long pfn)
}
return true;
}
+
+/*
+ * Skim over the P2M tree looking at pages that are either filled with
+ * INVALID_P2M_ENTRY or with 1:1 PFNs. If found, re-use that page and
+ * replace the P2M leaf with a p2m_missing or p2m_identity.
+ * Stick the old page in the new P2M tree location.
+ */
+bool __init early_can_reuse_p2m_middle(unsigned long set_pfn, unsigned long set_mfn)
+{
+ unsigned topidx;
+ unsigned mididx;
+ unsigned ident_pfns;
+ unsigned inv_pfns;
+ unsigned long *p2m;
+ unsigned long *mid_mfn_p;
+ unsigned idx;
+ unsigned long pfn;
+
+ /* We only look when this entails a P2M middle layer */
+ if (p2m_index(set_pfn))
+ return false;
+
+ for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn += P2M_PER_PAGE) {
+ topidx = p2m_top_index(pfn);
+
+ if (!p2m_top[topidx])
+ continue;
+
+ if (p2m_top[topidx] == p2m_mid_missing)
+ continue;
+
+ mididx = p2m_mid_index(pfn);
+ p2m = p2m_top[topidx][mididx];
+ if (!p2m)
+ continue;
+
+ if ((p2m == p2m_missing) || (p2m == p2m_identity))
+ continue;
+
+ if ((unsigned long)p2m == INVALID_P2M_ENTRY)
+ continue;
+
+ ident_pfns = 0;
+ inv_pfns = 0;
+ for (idx = 0; idx < P2M_PER_PAGE; idx++) {
+ /* IDENTITY_PFNs are 1:1 */
+ if (p2m[idx] == IDENTITY_FRAME(pfn + idx))
+ ident_pfns++;
+ else if (p2m[idx] == INVALID_P2M_ENTRY)
+ inv_pfns++;
+ else
+ break;
+ }
+ if ((ident_pfns == P2M_PER_PAGE) || (inv_pfns == P2M_PER_PAGE))
+ goto found;
+ }
+ return false;
+found:
+ /* Found one, replace old with p2m_identity or p2m_missing */
+ p2m_top[topidx][mididx] = (ident_pfns ? p2m_identity : p2m_missing);
+ /* And the other for save/restore.. */
+ mid_mfn_p = p2m_top_mfn_p[topidx];
+ /* NOTE: Even if it is a p2m_identity it should still be point to
+ * a page filled with INVALID_P2M_ENTRY entries. */
+ mid_mfn_p[mididx] = virt_to_mfn(p2m_missing);
+
+ /* Reset where we want to stick the old page in. */
+ topidx = p2m_top_index(set_pfn);
+ mididx = p2m_mid_index(set_pfn);
+
+ /* This shouldn't happen */
+ if (WARN_ON(p2m_top[topidx] == p2m_mid_missing))
+ early_alloc_p2m(set_pfn);
+
+ if (WARN_ON(p2m_top[topidx][mididx] != p2m_missing))
+ return false;
+
+ p2m_init(p2m);
+ p2m_top[topidx][mididx] = p2m;
+ mid_mfn_p = p2m_top_mfn_p[topidx];
+ mid_mfn_p[mididx] = virt_to_mfn(p2m);
+
+ return true;
+}
bool __init early_set_phys_to_machine(unsigned long pfn, unsigned long mfn)
{
if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
if (!early_alloc_p2m(pfn))
return false;
+ if (early_can_reuse_p2m_middle(pfn, mfn))
+ return __set_phys_to_machine(pfn, mfn);
+
if (!early_alloc_p2m_middle(pfn, false /* boundary crossover OK!*/))
return false;
@@ -739,9 +828,6 @@ int m2p_add_override(unsigned long mfn, struct page *page,
xen_mc_issue(PARAVIRT_LAZY_MMU);
}
- /* let's use dev_bus_addr to record the old mfn instead */
- kmap_op->dev_bus_addr = page->index;
- page->index = (unsigned long) kmap_op;
}
spin_lock_irqsave(&m2p_override_lock, flags);
list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]);
@@ -768,7 +854,8 @@ int m2p_add_override(unsigned long mfn, struct page *page,
return 0;
}
EXPORT_SYMBOL_GPL(m2p_add_override);
-int m2p_remove_override(struct page *page, bool clear_pte)
+int m2p_remove_override(struct page *page,
+ struct gnttab_map_grant_ref *kmap_op)
{
unsigned long flags;
unsigned long mfn;
@@ -798,10 +885,8 @@ int m2p_remove_override(struct page *page, bool clear_pte)
WARN_ON(!PagePrivate(page));
ClearPagePrivate(page);
- if (clear_pte) {
- struct gnttab_map_grant_ref *map_op =
- (struct gnttab_map_grant_ref *) page->index;
- set_phys_to_machine(pfn, map_op->dev_bus_addr);
+ set_phys_to_machine(pfn, page->index);
+ if (kmap_op != NULL) {
if (!PageHighMem(page)) {
struct multicall_space mcs;
struct gnttab_unmap_grant_ref *unmap_op;
@@ -813,13 +898,13 @@ int m2p_remove_override(struct page *page, bool clear_pte)
* issued. In this case handle is going to -1 because
* it hasn't been modified yet.
*/
- if (map_op->handle == -1)
+ if (kmap_op->handle == -1)
xen_mc_flush();
/*
- * Now if map_op->handle is negative it means that the
+ * Now if kmap_op->handle is negative it means that the
* hypercall actually returned an error.
*/
- if (map_op->handle == GNTST_general_error) {
+ if (kmap_op->handle == GNTST_general_error) {
printk(KERN_WARNING "m2p_remove_override: "
"pfn %lx mfn %lx, failed to modify kernel mappings",
pfn, mfn);
@@ -829,8 +914,8 @@ int m2p_remove_override(struct page *page, bool clear_pte)
mcs = xen_mc_entry(
sizeof(struct gnttab_unmap_grant_ref));
unmap_op = mcs.args;
- unmap_op->host_addr = map_op->host_addr;
- unmap_op->handle = map_op->handle;
+ unmap_op->host_addr = kmap_op->host_addr;
+ unmap_op->handle = kmap_op->handle;
unmap_op->dev_bus_addr = 0;
MULTI_grant_table_op(mcs.mc,
@@ -841,10 +926,9 @@ int m2p_remove_override(struct page *page, bool clear_pte)
set_pte_at(&init_mm, address, ptep,
pfn_pte(pfn, PAGE_KERNEL));
__flush_tlb_single(address);
- map_op->host_addr = 0;
+ kmap_op->host_addr = 0;
}
- } else
- set_phys_to_machine(pfn, page->index);
+ }
/* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present
* somewhere in this domain, even before being added to the