brain-hackers_pepepper-mirror
/
linux-brain
mirror of https://github.com/brain-hackers/linux-brain.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

[PATCH] KVM: MMU: Shadow page table caching 

Define a hashtable for caching shadow page tables. Look up the cache on
context switch (cr3 change) or during page faults.

The key to the cache is a combination of
- the guest page table frame number
- the number of paging levels in the guest
   * we can cache real mode, 32-bit mode, pae, and long mode page
     tables simultaneously.  this is useful for smp bootup.
- the guest page table table
   * some kernels use a page as both a page table and a page directory.  this
     allows multiple shadow pages to exist for that page, one per level
- the "quadrant"
   * 32-bit mode page tables span 4MB, whereas a shadow page table spans
     2MB.  similarly, a 32-bit page directory spans 4GB, while a shadow
     page directory spans 1GB.  the quadrant allows caching up to 4 shadow page
     tables for one guest page in one level.
- a "metaphysical" bit
   * for real mode, and for pse pages, there is no guest page table, so set
     the bit to avoid write protecting the page.

Signed-off-by: Avi Kivity <avi@qumranet.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Avi Kivity 2007-01-05 16:36:43 -08:00 committed by Linus Torvalds
parent 25c0de2cc6
commit cea0f0e7ea
3 changed files with 280 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
drivers/kvm/kvm.h
View File

@ -89,14 +89,53 @@ typedef unsigned long hva_t;
typedef u64 hpa_t;
typedef unsigned long hfn_t;
#define NR_PTE_CHAIN_ENTRIES 5
struct kvm_pte_chain {
u64 *parent_ptes[NR_PTE_CHAIN_ENTRIES];
struct hlist_node link;
};
/*
* kvm_mmu_page_role, below, is defined as:
*
* bits 0:3 - total guest paging levels (2-4, or zero for real mode)
* bits 4:7 - page table level for this shadow (1-4)
* bits 8:9 - page table quadrant for 2-level guests
* bit 16 - "metaphysical" - gfn is not a real page (huge page/real mode)
*/
union kvm_mmu_page_role {
unsigned word;
struct {
unsigned glevels : 4;
unsigned level : 4;
unsigned quadrant : 2;
unsigned pad_for_nice_hex_output : 6;
unsigned metaphysical : 1;
};
};
struct kvm_mmu_page {
struct list_head link;
struct hlist_node hash_link;
/*
* The following two entries are used to key the shadow page in the
* hash table.
*/
gfn_t gfn;
union kvm_mmu_page_role role;
hpa_t page_hpa;
unsigned long slot_bitmap; /* One bit set per slot which has memory
* in this shadow page.
*/
int global; /* Set if all ptes in this page are global */
u64 *parent_pte;
int multimapped; /* More than one parent_pte? */
union {
u64 *parent_pte; /* !multimapped */
struct hlist_head parent_ptes; /* multimapped, kvm_pte_chain */
};
};
struct vmcs {
@ -235,7 +274,11 @@ struct kvm {
spinlock_t lock; /* protects everything except vcpus */
int nmemslots;
struct kvm_memory_slot memslots[KVM_MEMORY_SLOTS];
/*
* Hash table of struct kvm_mmu_page.
*/
struct list_head active_mmu_pages;
struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES];
struct kvm_vcpu vcpus[KVM_MAX_VCPUS];
int memory_config_version;
int busy;

207
drivers/kvm/mmu.c
View File

@ -26,8 +26,8 @@
#include "vmx.h"
#include "kvm.h"
#define pgprintk(x...) do { } while (0)
#define rmap_printk(x...) do { } while (0)
#define pgprintk(x...) do { printk(x); } while (0)
#define rmap_printk(x...) do { printk(x); } while (0)
#define ASSERT(x) \
if (!(x)) { \
@ -35,8 +35,10 @@
__FILE__, __LINE__, #x); \
}
#define PT64_ENT_PER_PAGE 512
#define PT32_ENT_PER_PAGE 1024
#define PT64_PT_BITS 9
#define PT64_ENT_PER_PAGE (1 << PT64_PT_BITS)
#define PT32_PT_BITS 10
#define PT32_ENT_PER_PAGE (1 << PT32_PT_BITS)
#define PT_WRITABLE_SHIFT 1
@ -292,6 +294,11 @@ static int is_empty_shadow_page(hpa_t page_hpa)
return 1;
}
static unsigned kvm_page_table_hashfn(gfn_t gfn)
{
return gfn;
}
static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu,
u64 *parent_pte)
{
@ -306,10 +313,147 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu,
ASSERT(is_empty_shadow_page(page->page_hpa));
page->slot_bitmap = 0;
page->global = 1;
page->multimapped = 0;
page->parent_pte = parent_pte;
return page;
}
static void mmu_page_add_parent_pte(struct kvm_mmu_page *page, u64 *parent_pte)
{
struct kvm_pte_chain *pte_chain;
struct hlist_node *node;
int i;
if (!parent_pte)
return;
if (!page->multimapped) {
u64 *old = page->parent_pte;
if (!old) {
page->parent_pte = parent_pte;
return;
}
page->multimapped = 1;
pte_chain = kzalloc(sizeof(struct kvm_pte_chain), GFP_NOWAIT);
BUG_ON(!pte_chain);
INIT_HLIST_HEAD(&page->parent_ptes);
hlist_add_head(&pte_chain->link, &page->parent_ptes);
pte_chain->parent_ptes[0] = old;
}
hlist_for_each_entry(pte_chain, node, &page->parent_ptes, link) {
if (pte_chain->parent_ptes[NR_PTE_CHAIN_ENTRIES-1])
continue;
for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i)
if (!pte_chain->parent_ptes[i]) {
pte_chain->parent_ptes[i] = parent_pte;
return;
}
}
pte_chain = kzalloc(sizeof(struct kvm_pte_chain), GFP_NOWAIT);
BUG_ON(!pte_chain);
hlist_add_head(&pte_chain->link, &page->parent_ptes);
pte_chain->parent_ptes[0] = parent_pte;
}
static void mmu_page_remove_parent_pte(struct kvm_mmu_page *page,
u64 *parent_pte)
{
struct kvm_pte_chain *pte_chain;
struct hlist_node *node;
int i;
if (!page->multimapped) {
BUG_ON(page->parent_pte != parent_pte);
page->parent_pte = NULL;
return;
}
hlist_for_each_entry(pte_chain, node, &page->parent_ptes, link)
for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i) {
if (!pte_chain->parent_ptes[i])
break;
if (pte_chain->parent_ptes[i] != parent_pte)
continue;
while (i + 1 < NR_PTE_CHAIN_ENTRIES) {
pte_chain->parent_ptes[i]
= pte_chain->parent_ptes[i + 1];
++i;
}
pte_chain->parent_ptes[i] = NULL;
return;
}
BUG();
}
static struct kvm_mmu_page *kvm_mmu_lookup_page(struct kvm_vcpu *vcpu,
gfn_t gfn)
{
unsigned index;
struct hlist_head *bucket;
struct kvm_mmu_page *page;
struct hlist_node *node;
pgprintk("%s: looking for gfn %lx\n", __FUNCTION__, gfn);
index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
bucket = &vcpu->kvm->mmu_page_hash[index];
hlist_for_each_entry(page, node, bucket, hash_link)
if (page->gfn == gfn && !page->role.metaphysical) {
pgprintk("%s: found role %x\n",
__FUNCTION__, page->role.word);
return page;
}
return NULL;
}
static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
gfn_t gfn,
gva_t gaddr,
unsigned level,
int metaphysical,
u64 *parent_pte)
{
union kvm_mmu_page_role role;
unsigned index;
unsigned quadrant;
struct hlist_head *bucket;
struct kvm_mmu_page *page;
struct hlist_node *node;
role.word = 0;
role.glevels = vcpu->mmu.root_level;
role.level = level;
role.metaphysical = metaphysical;
if (vcpu->mmu.root_level <= PT32_ROOT_LEVEL) {
quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level));
quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
role.quadrant = quadrant;
}
pgprintk("%s: looking gfn %lx role %x\n", __FUNCTION__,
gfn, role.word);
index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
bucket = &vcpu->kvm->mmu_page_hash[index];
hlist_for_each_entry(page, node, bucket, hash_link)
if (page->gfn == gfn && page->role.word == role.word) {
mmu_page_add_parent_pte(page, parent_pte);
pgprintk("%s: found\n", __FUNCTION__);
return page;
}
page = kvm_mmu_alloc_page(vcpu, parent_pte);
if (!page)
return page;
pgprintk("%s: adding gfn %lx role %x\n", __FUNCTION__, gfn, role.word);
page->gfn = gfn;
page->role = role;
hlist_add_head(&page->hash_link, bucket);
return page;
}
static void kvm_mmu_put_page(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *page,
u64 *parent_pte)
{
mmu_page_remove_parent_pte(page, parent_pte);
}
static void page_header_update_slot(struct kvm *kvm, void *pte, gpa_t gpa)
{
int slot = memslot_id(kvm, gfn_to_memslot(kvm, gpa >> PAGE_SHIFT));
@ -389,11 +533,15 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, hpa_t p)
for (; ; level--) {
u32 index = PT64_INDEX(v, level);
u64 *table;
u64 pte;
ASSERT(VALID_PAGE(table_addr));
table = __va(table_addr);
if (level == 1) {
pte = table[index];
if (is_present_pte(pte) && is_writeble_pte(pte))
return 0;
mark_page_dirty(vcpu->kvm, v >> PAGE_SHIFT);
page_header_update_slot(vcpu->kvm, table, v);
table[index] = p | PT_PRESENT_MASK | PT_WRITABLE_MASK |
@ -404,8 +552,13 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, hpa_t p)
if (table[index] == 0) {
struct kvm_mmu_page *new_table;
gfn_t pseudo_gfn;
new_table = kvm_mmu_alloc_page(vcpu, &table[index]);
pseudo_gfn = (v & PT64_DIR_BASE_ADDR_MASK)
>> PAGE_SHIFT;
new_table = kvm_mmu_get_page(vcpu, pseudo_gfn,
v, level - 1,
1, &table[index]);
if (!new_table) {
pgprintk("nonpaging_map: ENOMEM\n");
return -ENOMEM;
@ -427,7 +580,6 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
hpa_t root = vcpu->mmu.root_hpa;
ASSERT(VALID_PAGE(root));
release_pt_page_64(vcpu, root, PT64_ROOT_LEVEL);
vcpu->mmu.root_hpa = INVALID_PAGE;
return;
}
@ -437,7 +589,6 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
ASSERT(VALID_PAGE(root));
root &= PT64_BASE_ADDR_MASK;
release_pt_page_64(vcpu, root, PT32E_ROOT_LEVEL - 1);
vcpu->mmu.pae_root[i] = INVALID_PAGE;
}
vcpu->mmu.root_hpa = INVALID_PAGE;
@ -446,13 +597,16 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
{
int i;
gfn_t root_gfn;
root_gfn = vcpu->cr3 >> PAGE_SHIFT;
#ifdef CONFIG_X86_64
if (vcpu->mmu.shadow_root_level == PT64_ROOT_LEVEL) {
hpa_t root = vcpu->mmu.root_hpa;
ASSERT(!VALID_PAGE(root));
root = kvm_mmu_alloc_page(vcpu, NULL)->page_hpa;
root = kvm_mmu_get_page(vcpu, root_gfn, 0,
PT64_ROOT_LEVEL, 0, NULL)->page_hpa;
vcpu->mmu.root_hpa = root;
return;
}
@ -461,7 +615,13 @@ static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
hpa_t root = vcpu->mmu.pae_root[i];
ASSERT(!VALID_PAGE(root));
root = kvm_mmu_alloc_page(vcpu, NULL)->page_hpa;
if (vcpu->mmu.root_level == PT32E_ROOT_LEVEL)
root_gfn = vcpu->pdptrs[i] >> PAGE_SHIFT;
else if (vcpu->mmu.root_level == 0)
root_gfn = 0;
root = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
PT32_ROOT_LEVEL, !is_paging(vcpu),
NULL)->page_hpa;
vcpu->mmu.pae_root[i] = root | PT_PRESENT_MASK;
}
vcpu->mmu.root_hpa = __pa(vcpu->mmu.pae_root);
@ -529,7 +689,7 @@ static int nonpaging_init_context(struct kvm_vcpu *vcpu)
context->inval_page = nonpaging_inval_page;
context->gva_to_gpa = nonpaging_gva_to_gpa;
context->free = nonpaging_free;
context->root_level = PT32E_ROOT_LEVEL;
context->root_level = 0;
context->shadow_root_level = PT32E_ROOT_LEVEL;
mmu_alloc_roots(vcpu);
ASSERT(VALID_PAGE(context->root_hpa));
@ -537,29 +697,18 @@ static int nonpaging_init_context(struct kvm_vcpu *vcpu)
return 0;
}
static void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu)
{
struct kvm_mmu_page *page, *npage;
list_for_each_entry_safe(page, npage, &vcpu->kvm->active_mmu_pages,
link) {
if (page->global)
continue;
if (!page->parent_pte)
continue;
*page->parent_pte = 0;
release_pt_page_64(vcpu, page->page_hpa, 1);
}
++kvm_stat.tlb_flush;
kvm_arch_ops->tlb_flush(vcpu);
}
static void paging_new_cr3(struct kvm_vcpu *vcpu)
{
mmu_free_roots(vcpu);
mmu_alloc_roots(vcpu);
kvm_mmu_flush_tlb(vcpu);
kvm_arch_ops->set_cr3(vcpu, vcpu->mmu.root_hpa);
}
static void mark_pagetable_nonglobal(void *shadow_pte)
@ -578,6 +727,16 @@ static inline void set_pte_common(struct kvm_vcpu *vcpu,
*shadow_pte |= access_bits << PT_SHADOW_BITS_OFFSET;
if (!dirty)
access_bits &= ~PT_WRITABLE_MASK;
if (access_bits & PT_WRITABLE_MASK) {
struct kvm_mmu_page *shadow;
shadow = kvm_mmu_lookup_page(vcpu, gaddr >> PAGE_SHIFT);
if (shadow)
pgprintk("%s: found shadow page for %lx, marking ro\n",
__FUNCTION__, (gfn_t)(gaddr >> PAGE_SHIFT));
if (shadow)
access_bits &= ~PT_WRITABLE_MASK;
}
if (access_bits & PT_WRITABLE_MASK)
mark_page_dirty(vcpu->kvm, gaddr >> PAGE_SHIFT);

62
drivers/kvm/paging_tmpl.h
View File

@ -32,6 +32,11 @@
#define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
#define PT_LEVEL_MASK(level) PT64_LEVEL_MASK(level)
#define PT_PTE_COPY_MASK PT64_PTE_COPY_MASK
#ifdef CONFIG_X86_64
#define PT_MAX_FULL_LEVELS 4
#else
#define PT_MAX_FULL_LEVELS 2
#endif
#elif PTTYPE == 32
#define pt_element_t u32
#define guest_walker guest_walker32
@ -42,6 +47,7 @@
#define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
#define PT_LEVEL_MASK(level) PT32_LEVEL_MASK(level)
#define PT_PTE_COPY_MASK PT32_PTE_COPY_MASK
#define PT_MAX_FULL_LEVELS 2
#else
#error Invalid PTTYPE value
#endif
@ -52,7 +58,7 @@
*/
struct guest_walker {
int level;
gfn_t table_gfn;
gfn_t table_gfn[PT_MAX_FULL_LEVELS];
pt_element_t *table;
pt_element_t *ptep;
pt_element_t inherited_ar;
@ -68,7 +74,9 @@ static void FNAME(walk_addr)(struct guest_walker *walker,
struct kvm_memory_slot *slot;
pt_element_t *ptep;
pt_element_t root;
gfn_t table_gfn;
pgprintk("%s: addr %lx\n", __FUNCTION__, addr);
walker->level = vcpu->mmu.root_level;
walker->table = NULL;
root = vcpu->cr3;
@ -81,8 +89,11 @@ static void FNAME(walk_addr)(struct guest_walker *walker,
--walker->level;
}
#endif
walker->table_gfn = (root & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
slot = gfn_to_memslot(vcpu->kvm, walker->table_gfn);
table_gfn = (root & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
walker->table_gfn[walker->level - 1] = table_gfn;
pgprintk("%s: table_gfn[%d] %lx\n", __FUNCTION__,
walker->level - 1, table_gfn);
slot = gfn_to_memslot(vcpu->kvm, table_gfn);
hpa = safe_gpa_to_hpa(vcpu, root & PT64_BASE_ADDR_MASK);
walker->table = kmap_atomic(pfn_to_page(hpa >> PAGE_SHIFT), KM_USER0);
@ -111,12 +122,15 @@ static void FNAME(walk_addr)(struct guest_walker *walker,
if (walker->level != 3 || is_long_mode(vcpu))
walker->inherited_ar &= walker->table[index];
walker->table_gfn = (*ptep & PT_BASE_ADDR_MASK) >> PAGE_SHIFT;
table_gfn = (*ptep & PT_BASE_ADDR_MASK) >> PAGE_SHIFT;
paddr = safe_gpa_to_hpa(vcpu, *ptep & PT_BASE_ADDR_MASK);
kunmap_atomic(walker->table, KM_USER0);
walker->table = kmap_atomic(pfn_to_page(paddr >> PAGE_SHIFT),
KM_USER0);
--walker->level;
walker->table_gfn[walker->level - 1 ] = table_gfn;
pgprintk("%s: table_gfn[%d] %lx\n", __FUNCTION__,
walker->level - 1, table_gfn);
}
walker->ptep = ptep;
}
@ -181,6 +195,8 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
u64 *shadow_ent = ((u64 *)__va(shadow_addr)) + index;
struct kvm_mmu_page *shadow_page;
u64 shadow_pte;
int metaphysical;
gfn_t table_gfn;
if (is_present_pte(*shadow_ent) || is_io_pte(*shadow_ent)) {
if (level == PT_PAGE_TABLE_LEVEL)
@ -205,7 +221,17 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
return shadow_ent;
}
shadow_page = kvm_mmu_alloc_page(vcpu, shadow_ent);
if (level - 1 == PT_PAGE_TABLE_LEVEL
&& walker->level == PT_DIRECTORY_LEVEL) {
metaphysical = 1;
table_gfn = (*guest_ent & PT_BASE_ADDR_MASK)
>> PAGE_SHIFT;
} else {
metaphysical = 0;
table_gfn = walker->table_gfn[level - 2];
}
shadow_page = kvm_mmu_get_page(vcpu, table_gfn, addr, level-1,
metaphysical, shadow_ent);
if (!shadow_page)
return ERR_PTR(-ENOMEM);
shadow_addr = shadow_page->page_hpa;
@ -227,7 +253,8 @@ static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu,
u64 *shadow_ent,
struct guest_walker *walker,
gva_t addr,
int user)
int user,
int *write_pt)
{
pt_element_t *guest_ent;
int writable_shadow;
@ -264,6 +291,12 @@ static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu,
}
gfn = (*guest_ent & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
if (kvm_mmu_lookup_page(vcpu, gfn)) {
pgprintk("%s: found shadow page for %lx, marking ro\n",
__FUNCTION__, gfn);
*write_pt = 1;
return 0;
}
mark_page_dirty(vcpu->kvm, gfn);
*shadow_ent |= PT_WRITABLE_MASK;
*guest_ent |= PT_DIRTY_MASK;
@ -294,7 +327,9 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
struct guest_walker walker;
u64 *shadow_pte;
int fixed;
int write_pt = 0;
pgprintk("%s: addr %lx err %x\n", __FUNCTION__, addr, error_code);
/*
* Look up the shadow pte for the faulting address.
*/
@ -302,6 +337,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
FNAME(walk_addr)(&walker, vcpu, addr);
shadow_pte = FNAME(fetch)(vcpu, addr, &walker);
if (IS_ERR(shadow_pte)) { /* must be -ENOMEM */
printk("%s: oom\n", __FUNCTION__);
nonpaging_flush(vcpu);
FNAME(release_walker)(&walker);
continue;
@ -313,20 +349,27 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
* The page is not mapped by the guest. Let the guest handle it.
*/
if (!shadow_pte) {
pgprintk("%s: not mapped\n", __FUNCTION__);
inject_page_fault(vcpu, addr, error_code);
FNAME(release_walker)(&walker);
return 0;
}
pgprintk("%s: shadow pte %p %llx\n", __FUNCTION__,
shadow_pte, *shadow_pte);
/*
* Update the shadow pte.
*/
if (write_fault)
fixed = FNAME(fix_write_pf)(vcpu, shadow_pte, &walker, addr,
user_fault);
user_fault, &write_pt);
else
fixed = fix_read_pf(shadow_pte);
pgprintk("%s: updated shadow pte %p %llx\n", __FUNCTION__,
shadow_pte, *shadow_pte);
FNAME(release_walker)(&walker);
/*
@ -344,14 +387,14 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
/*
* pte not present, guest page fault.
*/
if (pte_present && !fixed) {
if (pte_present && !fixed && !write_pt) {
inject_page_fault(vcpu, addr, error_code);
return 0;
}
++kvm_stat.pf_fixed;
return 0;
return write_pt;
}
static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)
@ -395,3 +438,4 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)
#undef PT_PTE_COPY_MASK
#undef PT_NON_PTE_COPY_MASK
#undef PT_DIR_BASE_ADDR_MASK
#undef PT_MAX_FULL_LEVELS