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[35.247.111.240]) by smtp.gmail.com with ESMTPSA id w81sm14021632pfc.106.2021.05.11.11.55.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 11 May 2021 11:55:40 -0700 (PDT) Date: Tue, 11 May 2021 18:55:37 +0000 From: Sean Christopherson To: Ben Gardon Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Paolo Bonzini , Peter Xu , Peter Shier , Yulei Zhang , Wanpeng Li , Xiao Guangrong , Kai Huang , Keqian Zhu , David Hildenbrand Subject: Re: [PATCH v4 4/7] KVM: mmu: Add slots_arch_lock for memslot arch fields Message-ID: References: <20210511171610.170160-1-bgardon@google.com> <20210511171610.170160-5-bgardon@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210511171610.170160-5-bgardon@google.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, May 11, 2021, Ben Gardon wrote: > Add a new lock to protect the arch-specific fields of memslots if they > need to be modified in a kvm->srcu read critical section. A future > commit will use this lock to lazily allocate memslot rmaps for x86. > > Signed-off-by: Ben Gardon > --- > include/linux/kvm_host.h | 9 +++++++++ > virt/kvm/kvm_main.c | 31 ++++++++++++++++++++++++++----- > 2 files changed, 35 insertions(+), 5 deletions(-) > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 8895b95b6a22..2d5e797fbb08 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -472,6 +472,15 @@ struct kvm { > #endif /* KVM_HAVE_MMU_RWLOCK */ > > struct mutex slots_lock; > + > + /* > + * Protects the arch-specific fields of struct kvm_memory_slots in > + * use by the VM. To be used under the slots_lock (above) or in a > + * kvm->srcu read cirtical section where acquiring the slots_lock ^^^^^^^^ critical > + * would lead to deadlock with the synchronize_srcu in > + * install_new_memslots. > + */ > + struct mutex slots_arch_lock; > struct mm_struct *mm; /* userspace tied to this vm */ > struct kvm_memslots __rcu *memslots[KVM_ADDRESS_SPACE_NUM]; > struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];