KVM: Remove the usage of paeg->private field by rmap
When kvm uses user-allocated pages in the future for the guest, we won't
be able to use page->private for rmap, since page->rmap is reserved for
the filesystem. So we move the rmap base pointers to the memory slot.
A side effect of this is that we need to store the gfn of each gpte in
the shadow pages, since the memory slot is addressed by gfn, instead of
hfn like struct page.
Signed-off-by: Izik Eidus <izik@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 051cdbe..8e58f3b 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -126,6 +126,8 @@
union kvm_mmu_page_role role;
u64 *spt;
+ /* hold the gfn of each spte inside spt */
+ gfn_t *gfns;
unsigned long slot_bitmap; /* One bit set per slot which has memory
* in this shadow page.
*/
@@ -159,7 +161,7 @@
u64 *pae_root;
};
-#define KVM_NR_MEM_OBJS 20
+#define KVM_NR_MEM_OBJS 40
struct kvm_mmu_memory_cache {
int nobjs;
@@ -402,6 +404,7 @@
unsigned long npages;
unsigned long flags;
struct page **phys_mem;
+ unsigned long *rmap;
unsigned long *dirty_bitmap;
};
@@ -554,6 +557,7 @@
extern hpa_t bad_page_address;
+gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn);
struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn);
struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn);
void mark_page_dirty(struct kvm *kvm, gfn_t gfn);
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 60798e3..2c3986f 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -329,6 +329,8 @@
__free_page(free->phys_mem[i]);
vfree(free->phys_mem);
}
+ if (!dont || free->rmap != dont->rmap)
+ vfree(free->rmap);
if (!dont || free->dirty_bitmap != dont->dirty_bitmap)
vfree(free->dirty_bitmap);
@@ -739,13 +741,18 @@
if (!new.phys_mem)
goto out_unlock;
+ new.rmap = vmalloc(npages * sizeof(struct page*));
+
+ if (!new.rmap)
+ goto out_unlock;
+
memset(new.phys_mem, 0, npages * sizeof(struct page *));
+ memset(new.rmap, 0, npages * sizeof(*new.rmap));
for (i = 0; i < npages; ++i) {
new.phys_mem[i] = alloc_page(GFP_HIGHUSER
| __GFP_ZERO);
if (!new.phys_mem[i])
goto out_unlock;
- set_page_private(new.phys_mem[i],0);
}
}
@@ -929,7 +936,7 @@
return r;
}
-static gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn)
+gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn)
{
int i;
struct kvm_mem_alias *alias;
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 17f5735..b294f89 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -276,7 +276,7 @@
rmap_desc_cache, 1);
if (r)
goto out;
- r = mmu_topup_memory_cache_page(&vcpu->mmu_page_cache, 4);
+ r = mmu_topup_memory_cache_page(&vcpu->mmu_page_cache, 8);
if (r)
goto out;
r = mmu_topup_memory_cache(&vcpu->mmu_page_header_cache,
@@ -327,35 +327,52 @@
}
/*
+ * Take gfn and return the reverse mapping to it.
+ * Note: gfn must be unaliased before this function get called
+ */
+
+static unsigned long *gfn_to_rmap(struct kvm *kvm, gfn_t gfn)
+{
+ struct kvm_memory_slot *slot;
+
+ slot = gfn_to_memslot(kvm, gfn);
+ return &slot->rmap[gfn - slot->base_gfn];
+}
+
+/*
* Reverse mapping data structures:
*
- * If page->private bit zero is zero, then page->private points to the
- * shadow page table entry that points to page_address(page).
+ * If rmapp bit zero is zero, then rmapp point to the shadw page table entry
+ * that points to page_address(page).
*
- * If page->private bit zero is one, (then page->private & ~1) points
- * to a struct kvm_rmap_desc containing more mappings.
+ * If rmapp bit zero is one, (then rmap & ~1) points to a struct kvm_rmap_desc
+ * containing more mappings.
*/
-static void rmap_add(struct kvm_vcpu *vcpu, u64 *spte)
+static void rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
{
- struct page *page;
+ struct kvm_mmu_page *page;
struct kvm_rmap_desc *desc;
+ unsigned long *rmapp;
int i;
if (!is_rmap_pte(*spte))
return;
- page = pfn_to_page((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT);
- if (!page_private(page)) {
+ gfn = unalias_gfn(vcpu->kvm, gfn);
+ page = page_header(__pa(spte));
+ page->gfns[spte - page->spt] = gfn;
+ rmapp = gfn_to_rmap(vcpu->kvm, gfn);
+ if (!*rmapp) {
rmap_printk("rmap_add: %p %llx 0->1\n", spte, *spte);
- set_page_private(page,(unsigned long)spte);
- } else if (!(page_private(page) & 1)) {
+ *rmapp = (unsigned long)spte;
+ } else if (!(*rmapp & 1)) {
rmap_printk("rmap_add: %p %llx 1->many\n", spte, *spte);
desc = mmu_alloc_rmap_desc(vcpu);
- desc->shadow_ptes[0] = (u64 *)page_private(page);
+ desc->shadow_ptes[0] = (u64 *)*rmapp;
desc->shadow_ptes[1] = spte;
- set_page_private(page,(unsigned long)desc | 1);
+ *rmapp = (unsigned long)desc | 1;
} else {
rmap_printk("rmap_add: %p %llx many->many\n", spte, *spte);
- desc = (struct kvm_rmap_desc *)(page_private(page) & ~1ul);
+ desc = (struct kvm_rmap_desc *)(*rmapp & ~1ul);
while (desc->shadow_ptes[RMAP_EXT-1] && desc->more)
desc = desc->more;
if (desc->shadow_ptes[RMAP_EXT-1]) {
@@ -368,7 +385,7 @@
}
}
-static void rmap_desc_remove_entry(struct page *page,
+static void rmap_desc_remove_entry(unsigned long *rmapp,
struct kvm_rmap_desc *desc,
int i,
struct kvm_rmap_desc *prev_desc)
@@ -382,44 +399,46 @@
if (j != 0)
return;
if (!prev_desc && !desc->more)
- set_page_private(page,(unsigned long)desc->shadow_ptes[0]);
+ *rmapp = (unsigned long)desc->shadow_ptes[0];
else
if (prev_desc)
prev_desc->more = desc->more;
else
- set_page_private(page,(unsigned long)desc->more | 1);
+ *rmapp = (unsigned long)desc->more | 1;
mmu_free_rmap_desc(desc);
}
-static void rmap_remove(u64 *spte)
+static void rmap_remove(struct kvm *kvm, u64 *spte)
{
- struct page *page;
struct kvm_rmap_desc *desc;
struct kvm_rmap_desc *prev_desc;
+ struct kvm_mmu_page *page;
+ unsigned long *rmapp;
int i;
if (!is_rmap_pte(*spte))
return;
- page = pfn_to_page((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT);
- if (!page_private(page)) {
+ page = page_header(__pa(spte));
+ rmapp = gfn_to_rmap(kvm, page->gfns[spte - page->spt]);
+ if (!*rmapp) {
printk(KERN_ERR "rmap_remove: %p %llx 0->BUG\n", spte, *spte);
BUG();
- } else if (!(page_private(page) & 1)) {
+ } else if (!(*rmapp & 1)) {
rmap_printk("rmap_remove: %p %llx 1->0\n", spte, *spte);
- if ((u64 *)page_private(page) != spte) {
+ if ((u64 *)*rmapp != spte) {
printk(KERN_ERR "rmap_remove: %p %llx 1->BUG\n",
spte, *spte);
BUG();
}
- set_page_private(page,0);
+ *rmapp = 0;
} else {
rmap_printk("rmap_remove: %p %llx many->many\n", spte, *spte);
- desc = (struct kvm_rmap_desc *)(page_private(page) & ~1ul);
+ desc = (struct kvm_rmap_desc *)(*rmapp & ~1ul);
prev_desc = NULL;
while (desc) {
for (i = 0; i < RMAP_EXT && desc->shadow_ptes[i]; ++i)
if (desc->shadow_ptes[i] == spte) {
- rmap_desc_remove_entry(page,
+ rmap_desc_remove_entry(rmapp,
desc, i,
prev_desc);
return;
@@ -433,28 +452,25 @@
static void rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn)
{
- struct kvm *kvm = vcpu->kvm;
- struct page *page;
struct kvm_rmap_desc *desc;
+ unsigned long *rmapp;
u64 *spte;
- page = gfn_to_page(kvm, gfn);
- BUG_ON(!page);
+ gfn = unalias_gfn(vcpu->kvm, gfn);
+ rmapp = gfn_to_rmap(vcpu->kvm, gfn);
- while (page_private(page)) {
- if (!(page_private(page) & 1))
- spte = (u64 *)page_private(page);
+ while (*rmapp) {
+ if (!(*rmapp & 1))
+ spte = (u64 *)*rmapp;
else {
- desc = (struct kvm_rmap_desc *)(page_private(page) & ~1ul);
+ desc = (struct kvm_rmap_desc *)(*rmapp & ~1ul);
spte = desc->shadow_ptes[0];
}
BUG_ON(!spte);
- BUG_ON((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT
- != page_to_pfn(page));
BUG_ON(!(*spte & PT_PRESENT_MASK));
BUG_ON(!(*spte & PT_WRITABLE_MASK));
rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
- rmap_remove(spte);
+ rmap_remove(vcpu->kvm, spte);
set_shadow_pte(spte, *spte & ~PT_WRITABLE_MASK);
kvm_flush_remote_tlbs(vcpu->kvm);
}
@@ -482,6 +498,7 @@
ASSERT(is_empty_shadow_page(page_head->spt));
list_del(&page_head->link);
__free_page(virt_to_page(page_head->spt));
+ __free_page(virt_to_page(page_head->gfns));
kfree(page_head);
++kvm->n_free_mmu_pages;
}
@@ -502,6 +519,7 @@
page = mmu_memory_cache_alloc(&vcpu->mmu_page_header_cache,
sizeof *page);
page->spt = mmu_memory_cache_alloc(&vcpu->mmu_page_cache, PAGE_SIZE);
+ page->gfns = mmu_memory_cache_alloc(&vcpu->mmu_page_cache, PAGE_SIZE);
set_page_private(virt_to_page(page->spt), (unsigned long)page);
list_add(&page->link, &vcpu->kvm->active_mmu_pages);
ASSERT(is_empty_shadow_page(page->spt));
@@ -667,7 +685,7 @@
if (page->role.level == PT_PAGE_TABLE_LEVEL) {
for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
if (is_shadow_present_pte(pt[i]))
- rmap_remove(&pt[i]);
+ rmap_remove(kvm, &pt[i]);
pt[i] = shadow_trap_nonpresent_pte;
}
kvm_flush_remote_tlbs(kvm);
@@ -832,7 +850,7 @@
page_header_update_slot(vcpu->kvm, table, v);
table[index] = p | PT_PRESENT_MASK | PT_WRITABLE_MASK |
PT_USER_MASK;
- rmap_add(vcpu, &table[index]);
+ rmap_add(vcpu, &table[index], v >> PAGE_SHIFT);
return 0;
}
@@ -1122,7 +1140,7 @@
pte = *spte;
if (is_shadow_present_pte(pte)) {
if (page->role.level == PT_PAGE_TABLE_LEVEL)
- rmap_remove(spte);
+ rmap_remove(vcpu->kvm, spte);
else {
child = page_header(pte & PT64_BASE_ADDR_MASK);
mmu_page_remove_parent_pte(child, spte);
@@ -1339,7 +1357,7 @@
for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
/* avoid RMW */
if (pt[i] & PT_WRITABLE_MASK) {
- rmap_remove(&pt[i]);
+ rmap_remove(kvm, &pt[i]);
pt[i] &= ~PT_WRITABLE_MASK;
}
}
@@ -1469,15 +1487,15 @@
struct kvm_rmap_desc *d;
for (j = 0; j < m->npages; ++j) {
- struct page *page = m->phys_mem[j];
+ unsigned long *rmapp = &m->rmap[j];
- if (!page->private)
+ if (!*rmapp)
continue;
- if (!(page->private & 1)) {
+ if (!(*rmapp & 1)) {
++nmaps;
continue;
}
- d = (struct kvm_rmap_desc *)(page->private & ~1ul);
+ d = (struct kvm_rmap_desc *)(*rmapp & ~1ul);
while (d) {
for (k = 0; k < RMAP_EXT; ++k)
if (d->shadow_ptes[k])
@@ -1529,18 +1547,18 @@
static void audit_write_protection(struct kvm_vcpu *vcpu)
{
struct kvm_mmu_page *page;
+ struct kvm_memory_slot *slot;
+ unsigned long *rmapp;
+ gfn_t gfn;
list_for_each_entry(page, &vcpu->kvm->active_mmu_pages, link) {
- hfn_t hfn;
- struct page *pg;
-
if (page->role.metaphysical)
continue;
- hfn = gpa_to_hpa(vcpu, (gpa_t)page->gfn << PAGE_SHIFT)
- >> PAGE_SHIFT;
- pg = pfn_to_page(hfn);
- if (pg->private)
+ slot = gfn_to_memslot(vcpu->kvm, page->gfn);
+ gfn = unalias_gfn(vcpu->kvm, page->gfn);
+ rmapp = &slot->rmap[gfn - slot->base_gfn];
+ if (*rmapp)
printk(KERN_ERR "%s: (%s) shadow page has writable"
" mappings: gfn %lx role %x\n",
__FUNCTION__, audit_msg, page->gfn,
diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index be0f852..fbe595f 100644
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -295,7 +295,8 @@
set_shadow_pte(shadow_pte, spte);
page_header_update_slot(vcpu->kvm, shadow_pte, gaddr);
if (!was_rmapped)
- rmap_add(vcpu, shadow_pte);
+ rmap_add(vcpu, shadow_pte, (gaddr & PT64_BASE_ADDR_MASK)
+ >> PAGE_SHIFT);
if (!ptwrite || !*ptwrite)
vcpu->last_pte_updated = shadow_pte;
}
