Try to make some code simplifications allowed by the use of a mutex instead of a
spinlock. As we can keep the lock longer, we don't have to release it and then
have to check if the environment has not been modified before re-taking it. We
can remove kvm->busy and kvm->memory_config_version.
Signed-off-by: Laurent Vivier <[EMAIL PROTECTED]>
Index: kvm/drivers/kvm/kvm.h
===================================================================
--- kvm.orig/drivers/kvm/kvm.h 2007-08-30 13:40:10.000000000 +0200
+++ kvm/drivers/kvm/kvm.h 2007-08-30 13:40:13.000000000 +0200
@@ -407,8 +407,6 @@ struct kvm {
int n_free_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;
unsigned long rmap_overflow;
struct list_head vm_list;
struct file *filp;
Index: kvm/drivers/kvm/kvm_main.c
===================================================================
--- kvm.orig/drivers/kvm/kvm_main.c 2007-08-30 13:40:10.000000000 +0200
+++ kvm/drivers/kvm/kvm_main.c 2007-08-30 13:40:35.000000000 +0200
@@ -615,7 +615,6 @@ static int kvm_vm_ioctl_set_memory_regio
unsigned long i;
struct kvm_memory_slot *memslot;
struct kvm_memory_slot old, new;
- int memory_config_version;
r = -EINVAL;
/* General sanity checks */
@@ -635,10 +634,8 @@ static int kvm_vm_ioctl_set_memory_regio
if (!npages)
mem->flags &= ~KVM_MEM_LOG_DIRTY_PAGES;
-raced:
mutex_lock(&kvm->lock);
- memory_config_version = kvm->memory_config_version;
new = old = *memslot;
new.base_gfn = base_gfn;
@@ -661,11 +658,6 @@ raced:
(base_gfn >= s->base_gfn + s->npages)))
goto out_unlock;
}
- /*
- * Do memory allocations outside lock. memory_config_version will
- * detect any races.
- */
- mutex_unlock(&kvm->lock);
/* Deallocate if slot is being removed */
if (!npages)
@@ -682,14 +674,14 @@ raced:
new.phys_mem = vmalloc(npages * sizeof(struct page *));
if (!new.phys_mem)
- goto out_free;
+ goto out_unlock;
memset(new.phys_mem, 0, npages * sizeof(struct page *));
for (i = 0; i < npages; ++i) {
new.phys_mem[i] = alloc_page(GFP_HIGHUSER
| __GFP_ZERO);
if (!new.phys_mem[i])
- goto out_free;
+ goto out_unlock;
set_page_private(new.phys_mem[i],0);
}
}
@@ -700,27 +692,14 @@ raced:
new.dirty_bitmap = vmalloc(dirty_bytes);
if (!new.dirty_bitmap)
- goto out_free;
+ goto out_unlock;
memset(new.dirty_bitmap, 0, dirty_bytes);
}
- mutex_lock(&kvm->lock);
-
- if (memory_config_version != kvm->memory_config_version) {
- mutex_unlock(&kvm->lock);
- kvm_free_physmem_slot(&new, &old);
- goto raced;
- }
-
- r = -EAGAIN;
- if (kvm->busy)
- goto out_unlock;
-
if (mem->slot >= kvm->nmemslots)
kvm->nmemslots = mem->slot + 1;
*memslot = new;
- ++kvm->memory_config_version;
kvm_mmu_slot_remove_write_access(kvm, mem->slot);
kvm_flush_remote_tlbs(kvm);
@@ -732,7 +711,6 @@ raced:
out_unlock:
mutex_unlock(&kvm->lock);
-out_free:
kvm_free_physmem_slot(&new, &old);
out:
return r;
@@ -751,12 +729,6 @@ static int kvm_vm_ioctl_get_dirty_log(st
mutex_lock(&kvm->lock);
- /*
- * Prevent changes to guest memory configuration even while the lock
- * is not taken.
- */
- ++kvm->busy;
- mutex_unlock(&kvm->lock);
r = -EINVAL;
if (log->slot >= KVM_MEMORY_SLOTS)
goto out;
@@ -777,18 +749,14 @@ static int kvm_vm_ioctl_get_dirty_log(st
/* If nothing is dirty, don't bother messing with page tables. */
if (any) {
- mutex_lock(&kvm->lock);
kvm_mmu_slot_remove_write_access(kvm, log->slot);
kvm_flush_remote_tlbs(kvm);
memset(memslot->dirty_bitmap, 0, n);
- mutex_unlock(&kvm->lock);
}
r = 0;
out:
- mutex_lock(&kvm->lock);
- --kvm->busy;
mutex_unlock(&kvm->lock);
return r;
}
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