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KVM: Use prepare/commit hooks to handle generic memslot metadata updates

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Handle the generic memslot metadata, a.k.a. dirty bitmap, updates at the
same time that arch handles it's own metadata updates, i.e. at memslot
prepare and commit.  This will simplify converting @new to a dynamically
allocated object, and more closely aligns common KVM with architecture
code.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <2ddd5446e3706fe3c1e52e3df279f04c458be830.1638817640.git.maciej.szmigiero@oracle.com>
This commit is contained in:
Sean Christopherson 2021-12-06 20:54:19 +01:00 committed by Paolo Bonzini
parent 6a99c6e3f5
commit 07921665a6
1 changed files with 66 additions and 43 deletions
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109
virt/kvm/kvm_main.c
View File

@ -1549,6 +1549,69 @@ static void kvm_copy_memslots_arch(struct kvm_memslots *to,
to->memslots[i].arch = from->memslots[i].arch;
}
static int kvm_prepare_memory_region(struct kvm *kvm,
const struct kvm_memory_slot *old,
struct kvm_memory_slot *new,
enum kvm_mr_change change)
{
int r;
/*
* If dirty logging is disabled, nullify the bitmap; the old bitmap
* will be freed on "commit". If logging is enabled in both old and
* new, reuse the existing bitmap. If logging is enabled only in the
* new and KVM isn't using a ring buffer, allocate and initialize a
* new bitmap.
*/
if (!(new->flags & KVM_MEM_LOG_DIRTY_PAGES))
new->dirty_bitmap = NULL;
else if (old->dirty_bitmap)
new->dirty_bitmap = old->dirty_bitmap;
else if (!kvm->dirty_ring_size) {
r = kvm_alloc_dirty_bitmap(new);
if (r)
return r;
if (kvm_dirty_log_manual_protect_and_init_set(kvm))
bitmap_set(new->dirty_bitmap, 0, new->npages);
}
r = kvm_arch_prepare_memory_region(kvm, old, new, change);
/* Free the bitmap on failure if it was allocated above. */
if (r && new->dirty_bitmap && !old->dirty_bitmap)
kvm_destroy_dirty_bitmap(new);
return r;
}
static void kvm_commit_memory_region(struct kvm *kvm,
struct kvm_memory_slot *old,
const struct kvm_memory_slot *new,
enum kvm_mr_change change)
{
/*
* Update the total number of memslot pages before calling the arch
* hook so that architectures can consume the result directly.
*/
if (change == KVM_MR_DELETE)
kvm->nr_memslot_pages -= old->npages;
else if (change == KVM_MR_CREATE)
kvm->nr_memslot_pages += new->npages;
kvm_arch_commit_memory_region(kvm, old, new, change);
/*
* Free the old memslot's metadata. On DELETE, free the whole thing,
* otherwise free the dirty bitmap as needed (the below effectively
* checks both the flags and whether a ring buffer is being used).
*/
if (change == KVM_MR_DELETE)
kvm_free_memslot(kvm, old);
else if (old->dirty_bitmap && !new->dirty_bitmap)
kvm_destroy_dirty_bitmap(old);
}
static int kvm_set_memslot(struct kvm *kvm,
struct kvm_memory_slot *new,
enum kvm_mr_change change)
@ -1635,27 +1698,14 @@ static int kvm_set_memslot(struct kvm *kvm,
old.as_id = new->as_id;
}
r = kvm_arch_prepare_memory_region(kvm, &old, new, change);
r = kvm_prepare_memory_region(kvm, &old, new, change);
if (r)
goto out_slots;
update_memslots(slots, new, change);
slots = install_new_memslots(kvm, new->as_id, slots);
/*
* Update the total number of memslot pages before calling the arch
* hook so that architectures can consume the result directly.
*/
if (change == KVM_MR_DELETE)
kvm->nr_memslot_pages -= old.npages;
else if (change == KVM_MR_CREATE)
kvm->nr_memslot_pages += new->npages;
kvm_arch_commit_memory_region(kvm, &old, new, change);
/* Free the old memslot's metadata. Note, this is the full copy!!! */
if (change == KVM_MR_DELETE)
kvm_free_memslot(kvm, &old);
kvm_commit_memory_region(kvm, &old, new, change);
kvfree(slots);
return 0;
@ -1751,7 +1801,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
if (!old.npages) {
change = KVM_MR_CREATE;
new.dirty_bitmap = NULL;
/*
* To simplify KVM internals, the total number of pages across
@ -1771,9 +1820,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
change = KVM_MR_FLAGS_ONLY;
else /* Nothing to change. */
return 0;
/* Copy dirty_bitmap from the current memslot. */
new.dirty_bitmap = old.dirty_bitmap;
}
if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
@ -1787,30 +1833,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
}
}
/* Allocate/free page dirty bitmap as needed */
if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES))
new.dirty_bitmap = NULL;
else if (!new.dirty_bitmap && !kvm->dirty_ring_size) {
r = kvm_alloc_dirty_bitmap(&new);
if (r)
return r;
if (kvm_dirty_log_manual_protect_and_init_set(kvm))
bitmap_set(new.dirty_bitmap, 0, new.npages);
}
r = kvm_set_memslot(kvm, &new, change);
if (r)
goto out_bitmap;
if (old.dirty_bitmap && !new.dirty_bitmap)
kvm_destroy_dirty_bitmap(&old);
return 0;
out_bitmap:
if (new.dirty_bitmap && !old.dirty_bitmap)
kvm_destroy_dirty_bitmap(&new);
return r;
return kvm_set_memslot(kvm, &new, change);
}
EXPORT_SYMBOL_GPL(__kvm_set_memory_region);