From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Paul Mackerras" <paulus@ozlabs.org>,
"Christian Borntraeger" <borntraeger@de.ibm.com>,
"Janosch Frank" <frankja@linux.ibm.com>,
"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>, "Marc Zyngier" <maz@kernel.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@vger.kernel.org,
kvm-ppc@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>,
"Peter Xu" <peterx@redhat.com>,
"Philippe Mathieu-Daudé" <f4bug@amsat.org>
Subject: [PATCH v6 12/22] KVM: Move memslot deletion to helper function
Date: Tue, 18 Feb 2020 13:07:26 -0800 [thread overview]
Message-ID: <20200218210736.16432-13-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20200218210736.16432-1-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, e.g. x86 frees
its arch specific memslot metadata during commit_memory_region().
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Tested-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
virt/kvm/kvm_main.c | 75 +++++++++++++++++++++++++++------------------
1 file changed, 46 insertions(+), 29 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f84bb0442a1b..1f56a0d042a0 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1043,6 +1043,27 @@ 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.
@@ -1092,7 +1113,17 @@ 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(), and the old
+ * memslot needs to be referenced after calling update_memslots(), e.g.
+ * to free its resources and for arch specific behavior.
+ */
+ 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;
@@ -1100,29 +1131,20 @@ 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)) {
@@ -1145,17 +1167,12 @@ 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:
--
2.24.1
next prev parent reply other threads:[~2020-02-18 21:08 UTC|newest]
Thread overview: 28+ 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 ` Sean Christopherson [this message]
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 ` [PATCH v6 18/22] KVM: Dynamically size memslot array based on number of used slots Sean Christopherson
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
2020-02-19 9:22 ` Sergei Shtylyov
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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