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KVM: introduce kvm->srcu and convert kvm_set_memory_region to SRCU update 

Use two steps for memslot deletion: mark the slot invalid (which stops
instantiation of new shadow pages for that slot, but allows destruction),
then instantiate the new empty slot.

Also simplifies kvm_handle_hva locking.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Marcelo Tosatti 2009-12-23 14:35:21 -02:00
parent 3ad26d8139
commit bc6678a33d
8 changed files with 136 additions and 64 deletions
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4
arch/ia64/kvm/kvm-ia64.c
View File

@ -1382,7 +1382,7 @@ static void kvm_release_vm_pages(struct kvm *kvm)
int i, j;
unsigned long base_gfn;
slots = kvm->memslots;
slots = rcu_dereference(kvm->memslots);
for (i = 0; i < slots->nmemslots; i++) {
memslot = &slots->memslots[i];
base_gfn = memslot->base_gfn;
@ -1837,6 +1837,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
struct kvm_memory_slot *memslot;
int is_dirty = 0;
down_write(&kvm->slots_lock);
spin_lock(&kvm->arch.dirty_log_lock);
r = kvm_ia64_sync_dirty_log(kvm, log);
@ -1856,6 +1857,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
}
r = 0;
out:
up_write(&kvm->slots_lock);
spin_unlock(&kvm->arch.dirty_log_lock);
return r;
}

28
arch/x86/kvm/mmu.c
View File

@ -29,6 +29,7 @@
#include <linux/swap.h>
#include <linux/hugetlb.h>
#include <linux/compiler.h>
#include <linux/srcu.h>
#include <asm/page.h>
#include <asm/cmpxchg.h>
@ -807,21 +808,15 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
{
int i, j;
int retval = 0;
struct kvm_memslots *slots = kvm->memslots;
struct kvm_memslots *slots;
slots = rcu_dereference(kvm->memslots);
/*
* If mmap_sem isn't taken, we can look the memslots with only
* the mmu_lock by skipping over the slots with userspace_addr == 0.
*/
for (i = 0; i < slots->nmemslots; i++) {
struct kvm_memory_slot *memslot = &slots->memslots[i];
unsigned long start = memslot->userspace_addr;
unsigned long end;
/* mmu_lock protects userspace_addr */
if (!start)
continue;
end = start + (memslot->npages << PAGE_SHIFT);
if (hva >= start && hva < end) {
gfn_t gfn_offset = (hva - start) >> PAGE_SHIFT;
@ -1617,7 +1612,7 @@ static void mmu_unshadow(struct kvm *kvm, gfn_t gfn)
static void page_header_update_slot(struct kvm *kvm, void *pte, gfn_t gfn)
{
int slot = memslot_id(kvm, gfn_to_memslot(kvm, gfn));
int slot = memslot_id(kvm, gfn);
struct kvm_mmu_page *sp = page_header(__pa(pte));
__set_bit(slot, sp->slot_bitmap);
@ -3021,9 +3016,11 @@ unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm)
int i;
unsigned int nr_mmu_pages;
unsigned int nr_pages = 0;
struct kvm_memslots *slots;
for (i = 0; i < kvm->memslots->nmemslots; i++)
nr_pages += kvm->memslots->memslots[i].npages;
slots = rcu_dereference(kvm->memslots);
for (i = 0; i < slots->nmemslots; i++)
nr_pages += slots->memslots[i].npages;
nr_mmu_pages = nr_pages * KVM_PERMILLE_MMU_PAGES / 1000;
nr_mmu_pages = max(nr_mmu_pages,
@ -3293,10 +3290,12 @@ static void audit_mappings(struct kvm_vcpu *vcpu)
static int count_rmaps(struct kvm_vcpu *vcpu)
{
int nmaps = 0;
int i, j, k;
int i, j, k, idx;
idx = srcu_read_lock(&kvm->srcu);
slots = rcu_dereference(kvm->memslots);
for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
struct kvm_memory_slot *m = &vcpu->kvm->memslots->memslots[i];
struct kvm_memory_slot *m = &slots->memslots[i];
struct kvm_rmap_desc *d;
for (j = 0; j < m->npages; ++j) {
@ -3319,6 +3318,7 @@ static int count_rmaps(struct kvm_vcpu *vcpu)
}
}
}
srcu_read_unlock(&kvm->srcu, idx);
return nmaps;
}

6
arch/x86/kvm/vmx.c
View File

@ -1503,7 +1503,11 @@ static void enter_pmode(struct kvm_vcpu *vcpu)
static gva_t rmode_tss_base(struct kvm *kvm)
{
if (!kvm->arch.tss_addr) {
gfn_t base_gfn = kvm->memslots->memslots[0].base_gfn +
struct kvm_memslots *slots;
gfn_t base_gfn;
slots = rcu_dereference(kvm->memslots);
base_gfn = kvm->memslots->memslots[0].base_gfn +
kvm->memslots->memslots[0].npages - 3;
return base_gfn << PAGE_SHIFT;
}

2
include/linux/kvm.h
View File

@ -103,7 +103,7 @@ struct kvm_userspace_memory_region {
/* for kvm_memory_region::flags */
#define KVM_MEM_LOG_DIRTY_PAGES 1UL
#define KVM_MEMSLOT_INVALID (1UL << 1)
/* for KVM_IRQ_LINE */
struct kvm_irq_level {

7
include/linux/kvm_host.h
View File

@ -162,6 +162,7 @@ struct kvm {
struct rw_semaphore slots_lock;
struct mm_struct *mm; /* userspace tied to this vm */
struct kvm_memslots *memslots;
struct srcu_struct srcu;
#ifdef CONFIG_KVM_APIC_ARCHITECTURE
u32 bsp_vcpu_id;
struct kvm_vcpu *bsp_vcpu;
@ -275,6 +276,7 @@ void kvm_set_page_accessed(struct page *page);
pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn);
pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
struct kvm_memory_slot *slot, gfn_t gfn);
int memslot_id(struct kvm *kvm, gfn_t gfn);
void kvm_release_pfn_dirty(pfn_t);
void kvm_release_pfn_clean(pfn_t pfn);
void kvm_set_pfn_dirty(pfn_t pfn);
@ -490,11 +492,6 @@ static inline void kvm_guest_exit(void)
current->flags &= ~PF_VCPU;
}
static inline int memslot_id(struct kvm *kvm, struct kvm_memory_slot *slot)
{
return slot - kvm->memslots->memslots;
}
static inline gpa_t gfn_to_gpa(gfn_t gfn)
{
return (gpa_t)gfn << PAGE_SHIFT;

8
virt/kvm/assigned-dev.c
View File

@ -504,12 +504,12 @@ out:
static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
struct kvm_assigned_pci_dev *assigned_dev)
{
int r = 0;
int r = 0, idx;
struct kvm_assigned_dev_kernel *match;
struct pci_dev *dev;
mutex_lock(&kvm->lock);
down_read(&kvm->slots_lock);
idx = srcu_read_lock(&kvm->srcu);
match = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head,
assigned_dev->assigned_dev_id);
@ -573,7 +573,7 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
}
out:
up_read(&kvm->slots_lock);
srcu_read_unlock(&kvm->srcu, idx);
mutex_unlock(&kvm->lock);
return r;
out_list_del:
@ -585,7 +585,7 @@ out_put:
pci_dev_put(dev);
out_free:
kfree(match);
up_read(&kvm->slots_lock);
srcu_read_unlock(&kvm->srcu, idx);
mutex_unlock(&kvm->lock);
return r;
}

4
virt/kvm/iommu.c
View File

@ -78,7 +78,7 @@ static int kvm_iommu_map_memslots(struct kvm *kvm)
int i, r = 0;
struct kvm_memslots *slots;
slots = kvm->memslots;
slots = rcu_dereference(kvm->memslots);
for (i = 0; i < slots->nmemslots; i++) {
r = kvm_iommu_map_pages(kvm, &slots->memslots[i]);
@ -214,7 +214,7 @@ static int kvm_iommu_unmap_memslots(struct kvm *kvm)
int i;
struct kvm_memslots *slots;
slots = kvm->memslots;
slots = rcu_dereference(kvm->memslots);
for (i = 0; i < slots->nmemslots; i++) {
kvm_iommu_put_pages(kvm, slots->memslots[i].base_gfn,

141
virt/kvm/kvm_main.c
View File

@ -44,6 +44,7 @@
#include <linux/bitops.h>
#include <linux/spinlock.h>
#include <linux/compat.h>
#include <linux/srcu.h>
#include <asm/processor.h>
#include <asm/io.h>
@ -213,7 +214,7 @@ static void kvm_mmu_notifier_invalidate_page(struct mmu_notifier *mn,
unsigned long address)
{
struct kvm *kvm = mmu_notifier_to_kvm(mn);
int need_tlb_flush;
int need_tlb_flush, idx;
/*
* When ->invalidate_page runs, the linux pte has been zapped
@ -233,10 +234,12 @@ static void kvm_mmu_notifier_invalidate_page(struct mmu_notifier *mn,
* pte after kvm_unmap_hva returned, without noticing the page
* is going to be freed.
*/
idx = srcu_read_lock(&kvm->srcu);
spin_lock(&kvm->mmu_lock);
kvm->mmu_notifier_seq++;
need_tlb_flush = kvm_unmap_hva(kvm, address);
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);
/* we've to flush the tlb before the pages can be freed */
if (need_tlb_flush)
@ -250,11 +253,14 @@ static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn,
pte_t pte)
{
struct kvm *kvm = mmu_notifier_to_kvm(mn);
int idx;
idx = srcu_read_lock(&kvm->srcu);
spin_lock(&kvm->mmu_lock);
kvm->mmu_notifier_seq++;
kvm_set_spte_hva(kvm, address, pte);
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);
}
static void kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
@ -263,8 +269,9 @@ static void kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
unsigned long end)
{
struct kvm *kvm = mmu_notifier_to_kvm(mn);
int need_tlb_flush = 0;
int need_tlb_flush = 0, idx;
idx = srcu_read_lock(&kvm->srcu);
spin_lock(&kvm->mmu_lock);
/*
* The count increase must become visible at unlock time as no
@ -275,6 +282,7 @@ static void kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
for (; start < end; start += PAGE_SIZE)
need_tlb_flush |= kvm_unmap_hva(kvm, start);
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);
/* we've to flush the tlb before the pages can be freed */
if (need_tlb_flush)
@ -312,11 +320,13 @@ static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,
unsigned long address)
{
struct kvm *kvm = mmu_notifier_to_kvm(mn);
int young;
int young, idx;
idx = srcu_read_lock(&kvm->srcu);
spin_lock(&kvm->mmu_lock);
young = kvm_age_hva(kvm, address);
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);
if (young)
kvm_flush_remote_tlbs(kvm);
@ -379,11 +389,15 @@ static struct kvm *kvm_create_vm(void)
kvm->memslots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
if (!kvm->memslots)
goto out_err;
if (init_srcu_struct(&kvm->srcu))
goto out_err;
#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
page = alloc_page(GFP_KERNEL | __GFP_ZERO);
if (!page)
if (!page) {
cleanup_srcu_struct(&kvm->srcu);
goto out_err;
}
kvm->coalesced_mmio_ring =
(struct kvm_coalesced_mmio_ring *)page_address(page);
@ -391,6 +405,7 @@ static struct kvm *kvm_create_vm(void)
r = kvm_init_mmu_notifier(kvm);
if (r) {
cleanup_srcu_struct(&kvm->srcu);
#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
put_page(page);
#endif
@ -480,6 +495,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
#else
kvm_arch_flush_shadow(kvm);
#endif
cleanup_srcu_struct(&kvm->srcu);
kvm_arch_destroy_vm(kvm);
hardware_disable_all();
mmdrop(mm);
@ -521,12 +537,13 @@ int __kvm_set_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem,
int user_alloc)
{
int r;
int r, flush_shadow = 0;
gfn_t base_gfn;
unsigned long npages;
unsigned long i;
struct kvm_memory_slot *memslot;
struct kvm_memory_slot old, new;
struct kvm_memslots *slots, *old_memslots;
r = -EINVAL;
/* General sanity checks */
@ -588,15 +605,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
memset(new.rmap, 0, npages * sizeof(*new.rmap));
new.user_alloc = user_alloc;
/*
* hva_to_rmmap() serialzies with the mmu_lock and to be
* safe it has to ignore memslots with !user_alloc &&
* !userspace_addr.
*/
if (user_alloc)
new.userspace_addr = mem->userspace_addr;
else
new.userspace_addr = 0;
new.userspace_addr = mem->userspace_addr;
}
if (!npages)
goto skip_lpage;
@ -651,8 +660,9 @@ skip_lpage:
if (!new.dirty_bitmap)
goto out_free;
memset(new.dirty_bitmap, 0, dirty_bytes);
/* destroy any largepage mappings for dirty tracking */
if (old.npages)
kvm_arch_flush_shadow(kvm);
flush_shadow = 1;
}
#else /* not defined CONFIG_S390 */
new.user_alloc = user_alloc;
@ -660,34 +670,72 @@ skip_lpage:
new.userspace_addr = mem->userspace_addr;
#endif /* not defined CONFIG_S390 */
if (!npages)
if (!npages) {
r = -ENOMEM;
slots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
if (!slots)
goto out_free;
memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
if (mem->slot >= slots->nmemslots)
slots->nmemslots = mem->slot + 1;
slots->memslots[mem->slot].flags |= KVM_MEMSLOT_INVALID;
old_memslots = kvm->memslots;
rcu_assign_pointer(kvm->memslots, slots);
synchronize_srcu_expedited(&kvm->srcu);
/* From this point no new shadow pages pointing to a deleted
* memslot will be created.
*
* validation of sp->gfn happens in:
* - gfn_to_hva (kvm_read_guest, gfn_to_pfn)
* - kvm_is_visible_gfn (mmu_check_roots)
*/
kvm_arch_flush_shadow(kvm);
kfree(old_memslots);
}
r = kvm_arch_prepare_memory_region(kvm, &new, old, mem, user_alloc);
if (r)
goto out_free;
spin_lock(&kvm->mmu_lock);
if (mem->slot >= kvm->memslots->nmemslots)
kvm->memslots->nmemslots = mem->slot + 1;
#ifdef CONFIG_DMAR
/* map the pages in iommu page table */
if (npages) {
r = kvm_iommu_map_pages(kvm, &new);
if (r)
goto out_free;
}
#endif
*memslot = new;
spin_unlock(&kvm->mmu_lock);
r = -ENOMEM;
slots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
if (!slots)
goto out_free;
memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
if (mem->slot >= slots->nmemslots)
slots->nmemslots = mem->slot + 1;
/* actual memory is freed via old in kvm_free_physmem_slot below */
if (!npages) {
new.rmap = NULL;
new.dirty_bitmap = NULL;
for (i = 0; i < KVM_NR_PAGE_SIZES - 1; ++i)
new.lpage_info[i] = NULL;
}
slots->memslots[mem->slot] = new;
old_memslots = kvm->memslots;
rcu_assign_pointer(kvm->memslots, slots);
synchronize_srcu_expedited(&kvm->srcu);
kvm_arch_commit_memory_region(kvm, mem, old, user_alloc);
kvm_free_physmem_slot(&old, npages ? &new : NULL);
/* Slot deletion case: we have to update the current slot */
spin_lock(&kvm->mmu_lock);
if (!npages)
*memslot = old;
spin_unlock(&kvm->mmu_lock);
#ifdef CONFIG_DMAR
/* map the pages in iommu page table */
r = kvm_iommu_map_pages(kvm, memslot);
if (r)
goto out;
#endif
kvm_free_physmem_slot(&old, &new);
kfree(old_memslots);
if (flush_shadow)
kvm_arch_flush_shadow(kvm);
return 0;
out_free:
@ -787,7 +835,7 @@ EXPORT_SYMBOL_GPL(kvm_is_error_hva);
struct kvm_memory_slot *gfn_to_memslot_unaliased(struct kvm *kvm, gfn_t gfn)
{
int i;
struct kvm_memslots *slots = kvm->memslots;
struct kvm_memslots *slots = rcu_dereference(kvm->memslots);
for (i = 0; i < slots->nmemslots; ++i) {
struct kvm_memory_slot *memslot = &slots->memslots[i];
@ -809,12 +857,15 @@ struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
{
int i;
struct kvm_memslots *slots = kvm->memslots;
struct kvm_memslots *slots = rcu_dereference(kvm->memslots);
gfn = unalias_gfn(kvm, gfn);
for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
struct kvm_memory_slot *memslot = &slots->memslots[i];
if (memslot->flags & KVM_MEMSLOT_INVALID)
continue;
if (gfn >= memslot->base_gfn
&& gfn < memslot->base_gfn + memslot->npages)
return 1;
@ -823,13 +874,31 @@ int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
}
EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);
int memslot_id(struct kvm *kvm, gfn_t gfn)
{
int i;
struct kvm_memslots *slots = rcu_dereference(kvm->memslots);
struct kvm_memory_slot *memslot = NULL;
gfn = unalias_gfn(kvm, gfn);
for (i = 0; i < slots->nmemslots; ++i) {
memslot = &slots->memslots[i];
if (gfn >= memslot->base_gfn
&& gfn < memslot->base_gfn + memslot->npages)
break;
}
return memslot - slots->memslots;
}
unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
{
struct kvm_memory_slot *slot;
gfn = unalias_gfn(kvm, gfn);
slot = gfn_to_memslot_unaliased(kvm, gfn);
if (!slot)
if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
return bad_hva();
return (slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE);
}