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KVM: introduce kvm->srcu and convert kvm_set_memory_region to SRCU up…
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…date

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 <[email protected]>
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@matosatti
matosatti committed Mar 1, 2010
1 parent 3ad26d8 commit bc6678a
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Showing 8 changed files with 136 additions and 64 deletions.
4 changes: 3 additions & 1 deletion arch/ia64/kvm/kvm-ia64.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand All @@ -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;
}
Expand Down
28 changes: 14 additions & 14 deletions arch/x86/kvm/mmu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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) {
Expand All @@ -3319,6 +3318,7 @@ static int count_rmaps(struct kvm_vcpu *vcpu)
}
}
}
srcu_read_unlock(&kvm->srcu, idx);
return nmaps;
}

Expand Down
6 changes: 5 additions & 1 deletion arch/x86/kvm/vmx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
}
Expand Down
2 changes: 1 addition & 1 deletion include/linux/kvm.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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 {
Expand Down
7 changes: 2 additions & 5 deletions include/linux/kvm_host.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;
Expand Down
8 changes: 4 additions & 4 deletions virt/kvm/assigned-dev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -504,12 +504,12 @@ static int kvm_vm_ioctl_deassign_dev_irq(struct kvm *kvm,
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);
Expand Down Expand Up @@ -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:
Expand All @@ -585,7 +585,7 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
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;
}
Expand Down
4 changes: 2 additions & 2 deletions virt/kvm/iommu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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]);
Expand Down Expand Up @@ -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,
Expand Down
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