linux-kernel - [PATCH v3 06/15] KVM: Explicitly free allocated-but-unused dirty bitmap

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Message-Id: <20191024230744.14543-7-sean.j.christopherson@intel.com>
Date:   Thu, 24 Oct 2019 16:07:35 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     James Hogan <jhogan@...nel.org>,
        Paul Mackerras <paulus@...abs.org>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Marc Zyngier <maz@...nel.org>
Cc:     David Hildenbrand <david@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        linux-mips@...r.kernel.org, kvm-ppc@...r.kernel.org,
        kvm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu, linux-kernel@...r.kernel.org,
        Christoffer Dall <christoffer.dall@....com>
Subject: [PATCH v3 06/15] KVM: Explicitly free allocated-but-unused dirty bitmap

Explicitly free an allocated-but-unused dirty bitmap instead of relying
on kvm_free_memslot() if an error occurs in __kvm_set_memory_region().
There is no longer a need to abuse kvm_free_memslot() to free arch
specific resources as arch specific code is now called only after the
common flow is guaranteed to succeed.  Arch code can still fail, but
it's responsible for its own cleanup in that case.

Eliminating the error path's abuse of kvm_free_memslot() paves the way
for simplifying kvm_free_memslot(), i.e. dropping its @dont param.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 virt/kvm/kvm_main.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9d6af9044304..a43902d9036d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1030,7 +1030,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 
 	slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
 	if (!slots)
-		goto out_free;
+		goto out_bitmap;
 	memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));
 
 	if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) {
@@ -1078,8 +1078,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)
 		slots = install_new_memslots(kvm, as_id, slots);
 	kvfree(slots);
-out_free:
-	kvm_free_memslot(kvm, &new, &old);
+out_bitmap:
+	if (new.dirty_bitmap && !old.dirty_bitmap)
+		kvm_destroy_dirty_bitmap(&new);
 out:
 	return r;
 }
-- 
2.22.0