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Subject[PATCH 32/40] KVM: use SRCU for dirty log
Date
From: Marcelo Tosatti <mtosatti@redhat.com>

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---
arch/x86/kvm/x86.c | 49 +++++++++++++++++++++++++++++++++++++++++--------
1 files changed, 41 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6a795be..2d7c040 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2416,27 +2416,60 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm,
int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
struct kvm_dirty_log *log)
{
- int r;
- int n;
+ int r, n, i;
struct kvm_memory_slot *memslot;
- int is_dirty = 0;
+ unsigned long is_dirty = 0;
+ unsigned long *dirty_bitmap = NULL;

down_write(&kvm->slots_lock);

- r = kvm_get_dirty_log(kvm, log, &is_dirty);
- if (r)
+ r = -EINVAL;
+ if (log->slot >= KVM_MEMORY_SLOTS)
+ goto out;
+
+ memslot = &kvm->memslots->memslots[log->slot];
+ r = -ENOENT;
+ if (!memslot->dirty_bitmap)
+ goto out;
+
+ n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+
+ r = -ENOMEM;
+ dirty_bitmap = vmalloc(n);
+ if (!dirty_bitmap)
goto out;
+ memset(dirty_bitmap, 0, n);
+
+ for (i = 0; !is_dirty && i < n/sizeof(long); i++)
+ is_dirty = memslot->dirty_bitmap[i];

/* If nothing is dirty, don't bother messing with page tables. */
if (is_dirty) {
+ struct kvm_memslots *slots, *old_slots;
+
spin_lock(&kvm->mmu_lock);
kvm_mmu_slot_remove_write_access(kvm, log->slot);
spin_unlock(&kvm->mmu_lock);
- memslot = &kvm->memslots->memslots[log->slot];
- n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
- memset(memslot->dirty_bitmap, 0, n);
+
+ slots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
+ if (!slots)
+ goto out_free;
+
+ memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
+ slots->memslots[log->slot].dirty_bitmap = dirty_bitmap;
+
+ old_slots = kvm->memslots;
+ rcu_assign_pointer(kvm->memslots, slots);
+ synchronize_srcu_expedited(&kvm->srcu);
+ dirty_bitmap = old_slots->memslots[log->slot].dirty_bitmap;
+ kfree(old_slots);
}
+
r = 0;
+ if (copy_to_user(log->dirty_bitmap, dirty_bitmap, n))
+ r = -EFAULT;
+out_free:
+ vfree(dirty_bitmap);
out:
up_write(&kvm->slots_lock);
return r;
--
1.6.5.3


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