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Message-Id: <2ddd5446e3706fe3c1e52e3df279f04c458be830.1638817640.git.maciej.szmigiero@oracle.com>
Date: Mon, 6 Dec 2021 20:54:19 +0100
From: "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
To: Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <seanjc@...gle.com>
Cc: Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>,
Igor Mammedov <imammedo@...hat.com>,
Marc Zyngier <maz@...nel.org>,
James Morse <james.morse@....com>,
Julien Thierry <julien.thierry.kdev@...il.com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Huacai Chen <chenhuacai@...nel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
Paul Mackerras <paulus@...abs.org>,
Christian Borntraeger <borntraeger@...ibm.com>,
Janosch Frank <frankja@...ux.ibm.com>,
David Hildenbrand <david@...hat.com>,
Cornelia Huck <cohuck@...hat.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
Anup Patel <anup.patel@....com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Alexandru Elisei <alexandru.elisei@....com>,
Ben Gardon <bgardon@...gle.com>, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v7 13/29] KVM: Use prepare/commit hooks to handle generic memslot metadata updates
From: Sean Christopherson <seanjc@...gle.com>
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@...gle.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@...cle.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@...cle.com>
---
virt/kvm/kvm_main.c | 109 +++++++++++++++++++++++++++-----------------
1 file changed, 66 insertions(+), 43 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index b778b8ab1885..1689f598fe9e 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1551,6 +1551,69 @@ 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)
@@ -1637,27 +1700,14 @@ 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;
@@ -1753,7 +1803,6 @@ 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
@@ -1773,9 +1822,6 @@ 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)) {
@@ -1789,30 +1835,7 @@ 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);
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