From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Wanpeng Li" <wanpengli@tencent.com>,
kvm@vger.kernel.org, "David Hildenbrand" <david@redhat.com>,
linux-mips@vger.kernel.org, "Paul Mackerras" <paulus@ozlabs.org>,
kvmarm@lists.cs.columbia.edu,
"Janosch Frank" <frankja@linux.ibm.com>,
"Marc Zyngier" <maz@kernel.org>, "Joerg Roedel" <joro@8bytes.org>,
"Christian Borntraeger" <borntraeger@de.ibm.com>,
kvm-ppc@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
"Jim Mattson" <jmattson@google.com>,
"Cornelia Huck" <cohuck@redhat.com>,
"Sean Christopherson" <sean.j.christopherson@intel.com>,
linux-kernel@vger.kernel.org,
"Vitaly Kuznetsov" <vkuznets@redhat.com>,
"Philippe Mathieu-Daudé" <f4bug@amsat.org>
Subject: [PATCH v6 18/22] KVM: Dynamically size memslot array based on number of used slots
Date: Tue, 18 Feb 2020 13:07:32 -0800 [thread overview]
Message-ID: <20200218210736.16432-19-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20200218210736.16432-1-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>
Reviewed-by: Peter Xu <peterx@redhat.com>
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 72b46d6f7f4a..f85cc9771ade 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -431,11 +431,11 @@ 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 2f2c434ab2c9..0583143aca90 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -566,7 +566,7 @@ 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;
}
@@ -1078,6 +1078,32 @@ 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,
@@ -1088,10 +1114,9 @@ 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
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next prev parent reply other threads:[~2020-02-18 21:08 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 21:07 [PATCH v6 00/22] KVM: Dynamically size memslot arrays Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 01/22] KVM: x86: Allocate new rmap and large page tracking when moving memslot Sean Christopherson
2020-02-19 19:10 ` Peter Xu
2020-02-18 21:07 ` [PATCH v6 02/22] KVM: Reinstall old memslots if arch preparation fails Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 03/22] KVM: Don't free new memslot if allocation of said memslot fails Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 04/22] KVM: PPC: Move memslot memory allocation into prepare_memory_region() Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 05/22] KVM: x86: Allocate memslot resources during prepare_memory_region() Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 06/22] KVM: Drop kvm_arch_create_memslot() Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 07/22] KVM: Explicitly free allocated-but-unused dirty bitmap Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 08/22] KVM: Refactor error handling for setting memory region Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 09/22] KVM: Move setting of memslot into helper routine Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 10/22] KVM: Drop "const" attribute from old memslot in commit_memory_region() Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 11/22] KVM: x86: Free arrays for old memslot when moving memslot's base gfn Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 12/22] KVM: Move memslot deletion to helper function Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 13/22] KVM: Simplify kvm_free_memslot() and all its descendents Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 14/22] KVM: Clean up local variable usage in __kvm_set_memory_region() Sean Christopherson
2020-02-21 17:43 ` Paolo Bonzini
2020-02-18 21:07 ` [PATCH v6 15/22] KVM: Provide common implementation for generic dirty log functions Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 16/22] KVM: Ensure validity of memslot with respect to kvm_get_dirty_log() Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 17/22] KVM: Terminate memslot walks via used_slots Sean Christopherson
2020-02-21 17:47 ` Paolo Bonzini
2020-02-18 21:07 ` Sean Christopherson [this message]
2020-02-18 21:07 ` [PATCH v6 19/22] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 20/22] KVM: x86/mmu: Move kvm_arch_flush_remote_tlbs_memslot() to mmu.c Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 21/22] KVM: x86/mmu: Use ranged-based TLB flush for dirty log memslot flush Sean Christopherson
[not found] ` <fdb72ab9-18d4-5719-2863-78cde4e97fae@cogentembedded.com>
2020-02-19 15:18 ` Sean Christopherson
2020-02-18 21:07 ` [PATCH v6 22/22] KVM: x86/mmu: Consolidate open coded variants of memslot TLB flushes Sean Christopherson
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