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>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Marc Zyngier" <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
Wanpeng Li <wanpengli@tencent.com>,
kvm@vger.kernel.org, David Hildenbrand <david@redhat.com>,
Joerg Roedel <joro@8bytes.org>, Cornelia Huck <cohuck@redhat.com>,
linux-mips@vger.kernel.org,
Sean Christopherson <sean.j.christopherson@intel.com>,
linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org,
Vitaly Kuznetsov <vkuznets@redhat.com>,
kvmarm@lists.cs.columbia.edu, Jim Mattson <jmattson@google.com>
Subject: [PATCH v3 09/15] KVM: Move memslot deletion to helper function
Date: Thu, 24 Oct 2019 16:07:38 -0700 [thread overview]
Message-ID: <20191024230744.14543-10-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20191024230744.14543-1-sean.j.christopherson@intel.com>
Move memslot deletion into its own routine so that the success path for
other memslot updates does not need to use kvm_free_memslot(), i.e. can
explicitly destroy the dirty bitmap when necessary. This paves the way
for dropping @dont from kvm_free_memslot(), i.e. all callers now pass
NULL for @dont.
Add a comment above the code to make a copy of the existing memslot
prior to deletion, it is not at all obvious that the pointer will become
stale during sorting and/or installation of new memslots.
Note, kvm_arch_commit_memory_region() allows an architecture to free
resources when moving a memslot or changing its flags, i.e. implement
logic similar to the dirty bitmap handling, if such functionality is
needed in the future.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Tested-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
virt/kvm/kvm_main.c | 73 +++++++++++++++++++++++++++------------------
1 file changed, 44 insertions(+), 29 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 860de4fadce6..2163a7157c63 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -980,6 +980,27 @@ static int kvm_set_memslot(struct kvm *kvm,
return r;
}
+static int kvm_delete_memslot(struct kvm *kvm,
+ const struct kvm_userspace_memory_region *mem,
+ struct kvm_memory_slot *old, int as_id)
+{
+ struct kvm_memory_slot new;
+ int r;
+
+ if (!old->npages)
+ return -EINVAL;
+
+ memset(&new, 0, sizeof(new));
+ new.id = old->id;
+
+ r = kvm_set_memslot(kvm, mem, old, &new, as_id, KVM_MR_DELETE);
+ if (r)
+ return r;
+
+ kvm_free_memslot(kvm, old, NULL);
+ return 0;
+}
+
/*
* Allocate some memory and give it an address in the guest physical address
* space.
@@ -1029,7 +1050,15 @@ int __kvm_set_memory_region(struct kvm *kvm,
if (npages > KVM_MEM_MAX_NR_PAGES)
return -EINVAL;
- new = old = *slot;
+ /*
+ * Make a full copy of the old memslot, the pointer will become stale
+ * when the memslots are re-sorted by update_memslots().
+ */
+ old = *slot;
+ if (!mem->memory_size)
+ return kvm_delete_memslot(kvm, mem, &old, as_id);
+
+ new = old;
new.id = id;
new.base_gfn = base_gfn;
@@ -1037,29 +1066,20 @@ int __kvm_set_memory_region(struct kvm *kvm,
new.flags = mem->flags;
new.userspace_addr = mem->userspace_addr;
- if (npages) {
- if (!old.npages)
- change = KVM_MR_CREATE;
- else { /* Modify an existing slot. */
- if ((new.userspace_addr != old.userspace_addr) ||
- (npages != old.npages) ||
- ((new.flags ^ old.flags) & KVM_MEM_READONLY))
- return -EINVAL;
-
- if (base_gfn != old.base_gfn)
- change = KVM_MR_MOVE;
- else if (new.flags != old.flags)
- change = KVM_MR_FLAGS_ONLY;
- else /* Nothing to change. */
- return 0;
- }
- } else {
- if (!old.npages)
+ if (!old.npages) {
+ change = KVM_MR_CREATE;
+ } else { /* Modify an existing slot. */
+ if ((new.userspace_addr != old.userspace_addr) ||
+ (npages != old.npages) ||
+ ((new.flags ^ old.flags) & KVM_MEM_READONLY))
return -EINVAL;
- change = KVM_MR_DELETE;
- new.base_gfn = 0;
- new.flags = 0;
+ if (base_gfn != old.base_gfn)
+ change = KVM_MR_MOVE;
+ else if (new.flags != old.flags)
+ change = KVM_MR_FLAGS_ONLY;
+ else /* Nothing to change. */
+ return 0;
}
if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
@@ -1082,17 +1102,12 @@ int __kvm_set_memory_region(struct kvm *kvm,
return r;
}
- /* actual memory is freed via old in kvm_free_memslot below */
- if (change == KVM_MR_DELETE) {
- new.dirty_bitmap = NULL;
- memset(&new.arch, 0, sizeof(new.arch));
- }
-
r = kvm_set_memslot(kvm, mem, &old, &new, as_id, change);
if (r)
goto out_bitmap;
- kvm_free_memslot(kvm, &old, &new);
+ if (old.dirty_bitmap && !new.dirty_bitmap)
+ kvm_destroy_dirty_bitmap(&old);
return 0;
out_bitmap:
--
2.22.0
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next prev parent reply other threads:[~2019-10-24 23:08 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-24 23:07 [PATCH v3 00/15] KVM: Dynamically size memslot arrays Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 01/15] KVM: Reinstall old memslots if arch preparation fails Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 02/15] KVM: Don't free new memslot if allocation of said memslot fails Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 03/15] KVM: PPC: Move memslot memory allocation into prepare_memory_region() Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 04/15] KVM: x86: Allocate memslot resources during prepare_memory_region() Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 05/15] KVM: Drop kvm_arch_create_memslot() Sean Christopherson
2019-12-16 8:04 ` Christian Borntraeger
2019-10-24 23:07 ` [PATCH v3 06/15] KVM: Explicitly free allocated-but-unused dirty bitmap Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 07/15] KVM: Refactor error handling for setting memory region Sean Christopherson
2019-12-05 9:49 ` Philippe Mathieu-Daudé
2019-10-24 23:07 ` [PATCH v3 08/15] KVM: Move setting of memslot into helper routine Sean Christopherson
2019-12-05 9:54 ` Philippe Mathieu-Daudé
2019-10-24 23:07 ` Sean Christopherson [this message]
2019-10-24 23:07 ` [PATCH v3 10/15] KVM: Simplify kvm_free_memslot() and all its descendents Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 11/15] KVM: Clean up local variable usage in __kvm_set_memory_region() Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 12/15] KVM: Provide common implementation for generic dirty log functions Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 13/15] KVM: Ensure validity of memslot with respect to kvm_get_dirty_log() Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 14/15] KVM: Terminate memslot walks via used_slots Sean Christopherson
2019-10-24 23:07 ` [PATCH v3 15/15] KVM: Dynamically size memslot array based on number of used slots Sean Christopherson
2019-10-25 13:28 ` [PATCH v3 00/15] KVM: Dynamically size memslot arrays Christoffer Dall
2019-10-25 16:30 ` Marc Zyngier
2019-12-03 22:14 ` Sean Christopherson
2019-12-13 20:01 ` Sean Christopherson
2019-12-16 8:25 ` Christian Borntraeger
2019-12-17 17:55 ` Sean Christopherson
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