KVM: Simplify memory allocation
The mutex->splinlock convertion alllows us to make some code simplifications.
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 <Laurent.Vivier@bull.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 9dffbbe..8da13a4 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -679,7 +679,6 @@
unsigned long i;
struct kvm_memory_slot *memslot;
struct kvm_memory_slot old, new;
- int memory_config_version;
r = -EINVAL;
/* General sanity checks */
@@ -699,10 +698,8 @@
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;
@@ -725,11 +722,6 @@
(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)
@@ -746,14 +738,14 @@
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);
}
}
@@ -764,27 +756,14 @@
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);
@@ -796,7 +775,6 @@
out_unlock:
mutex_unlock(&kvm->lock);
-out_free:
kvm_free_physmem_slot(&new, &old);
out:
return r;
@@ -815,12 +793,6 @@
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;
@@ -841,18 +813,14 @@
/* 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;
}