From: Sean Christopherson <sean.j.christopherson@intel.com>
To: James Hogan <jhogan@kernel.org>,
Paul Mackerras <paulus@ozlabs.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Marc Zyngier <maz@kernel.org>
Cc: "David Hildenbrand" <david@redhat.com>,
"Cornelia Huck" <cohuck@redhat.com>,
"Sean Christopherson" <sean.j.christopherson@intel.com>,
"Vitaly Kuznetsov" <vkuznets@redhat.com>,
"Wanpeng Li" <wanpengli@tencent.com>,
"Jim Mattson" <jmattson@google.com>,
"Joerg Roedel" <joro@8bytes.org>,
"James Morse" <james.morse@arm.com>,
"Julien Thierry" <julien.thierry.kdev@gmail.com>,
"Suzuki K Poulose" <suzuki.poulose@arm.com>,
linux-mips@vger.kernel.org, kvm-ppc@vger.kernel.org,
kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
"Christoffer Dall" <christoffer.dall@arm.com>,
"Philippe Mathieu-Daudé" <f4bug@amsat.org>
Subject: [PATCH v4 18/19] KVM: Dynamically size memslot array based on number of used slots
Date: Tue, 17 Dec 2019 12:40:40 -0800 [thread overview]
Message-ID: <20191217204041.10815-19-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20191217204041.10815-1-sean.j.christopherson@intel.com>
Now that the memslot logic doesn't assume memslots are always non-NULL,
dynamically size the array of memslots instead of unconditionally
allocating memory for the maximum number of memslots.
Note, because a to-be-deleted memslot must first be invalidated, the
array size cannot be immediately reduced when deleting a memslot.
However, consecutive deletions will realize the memory savings, i.e.
a second deletion will trim the entry.
Tested-by: Christoffer Dall <christoffer.dall@arm.com>
Tested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
include/linux/kvm_host.h | 2 +-
virt/kvm/kvm_main.c | 31 ++++++++++++++++++++++++++++---
2 files changed, 29 insertions(+), 4 deletions(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 49b6b457a157..eecfa1fe0fc7 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -433,11 +433,11 @@ static inline int kvm_arch_vcpu_memslots_id(struct kvm_vcpu *vcpu)
*/
struct kvm_memslots {
u64 generation;
- struct kvm_memory_slot memslots[KVM_MEM_SLOTS_NUM];
/* The mapping table from slot id to the index in memslots[]. */
short id_to_index[KVM_MEM_SLOTS_NUM];
atomic_t lru_slot;
int used_slots;
+ struct kvm_memory_slot memslots[];
};
struct kvm {
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a1566c5cee26..57926579551b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -569,7 +569,7 @@ static struct kvm_memslots *kvm_alloc_memslots(void)
return NULL;
for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)
- slots->id_to_index[i] = slots->memslots[i].id = -1;
+ slots->id_to_index[i] = -1;
return slots;
}
@@ -1081,6 +1081,32 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
return old_memslots;
}
+/*
+ * Note, at a minimum, the current number of used slots must be allocated, even
+ * when deleting a memslot, as we need a complete duplicate of the memslots for
+ * use when invalidating a memslot prior to deleting/moving the memslot.
+ */
+static struct kvm_memslots *kvm_dup_memslots(struct kvm_memslots *old,
+ enum kvm_mr_change change)
+{
+ struct kvm_memslots *slots;
+ size_t old_size, new_size;
+
+ old_size = sizeof(struct kvm_memslots) +
+ (sizeof(struct kvm_memory_slot) * old->used_slots);
+
+ if (change == KVM_MR_CREATE)
+ new_size = old_size + sizeof(struct kvm_memory_slot);
+ else
+ new_size = old_size;
+
+ slots = kvzalloc(new_size, GFP_KERNEL_ACCOUNT);
+ if (likely(slots))
+ memcpy(slots, old, old_size);
+
+ return slots;
+}
+
static int kvm_set_memslot(struct kvm *kvm,
const struct kvm_userspace_memory_region *mem,
struct kvm_memory_slot *old,
@@ -1091,10 +1117,9 @@ static int kvm_set_memslot(struct kvm *kvm,
struct kvm_memslots *slots;
int r;
- slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
+ slots = kvm_dup_memslots(__kvm_memslots(kvm, as_id), change);
if (!slots)
return -ENOMEM;
- memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));
if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
/*
--
2.24.1
next prev parent reply other threads:[~2019-12-17 20:41 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot Sean Christopherson
2019-12-17 20:48 ` Sean Christopherson
2019-12-17 20:50 ` Sean Christopherson
2019-12-17 21:56 ` Peter Xu
2019-12-17 22:20 ` Sean Christopherson
2019-12-17 22:37 ` Peter Xu
2019-12-17 20:40 ` [PATCH v4 02/19] KVM: Reinstall old memslots if arch preparation fails Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 03/19] KVM: Don't free new memslot if allocation of said memslot fails Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 04/19] KVM: PPC: Move memslot memory allocation into prepare_memory_region() Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 05/19] KVM: x86: Allocate memslot resources during prepare_memory_region() Sean Christopherson
2019-12-17 22:07 ` Peter Xu
2019-12-17 20:40 ` [PATCH v4 06/19] KVM: Drop kvm_arch_create_memslot() Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 07/19] KVM: Explicitly free allocated-but-unused dirty bitmap Sean Christopherson
2019-12-17 22:24 ` Peter Xu
2019-12-17 22:51 ` Sean Christopherson
2019-12-18 16:17 ` Peter Xu
2019-12-17 20:40 ` [PATCH v4 08/19] KVM: Refactor error handling for setting memory region Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 09/19] KVM: Move setting of memslot into helper routine Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 10/19] KVM: Drop "const" attribute from old memslot in commit_memory_region() Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 11/19] KVM: x86: Free arrays for old memslot when moving memslot's base gfn Sean Christopherson
2019-12-17 22:48 ` Peter Xu
2019-12-17 20:40 ` [PATCH v4 12/19] KVM: Move memslot deletion to helper function Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 13/19] KVM: Simplify kvm_free_memslot() and all its descendents Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 14/19] KVM: Clean up local variable usage in __kvm_set_memory_region() Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 15/19] KVM: Provide common implementation for generic dirty log functions Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 16/19] KVM: Ensure validity of memslot with respect to kvm_get_dirty_log() Sean Christopherson
2019-12-24 18:19 ` Peter Xu
2020-01-14 18:25 ` Sean Christopherson
2020-02-06 22:03 ` Peter Xu
2020-02-07 18:52 ` Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 17/19] KVM: Terminate memslot walks via used_slots Sean Christopherson
2019-12-17 20:40 ` Sean Christopherson [this message]
2019-12-17 20:40 ` [PATCH v4 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION Sean Christopherson
2019-12-18 11:29 ` Christian Borntraeger
2019-12-18 11:39 ` Christian Borntraeger
2019-12-18 16:39 ` Sean Christopherson
2020-03-24 9:43 ` Christian Borntraeger
2020-03-24 18:20 ` Sean Christopherson
2019-12-18 11:40 ` [PATCH v4 00/19] KVM: Dynamically size memslot arrays Christian Borntraeger
2019-12-18 18:10 ` Marc Zyngier
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