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[174.95.215.133]) by smtp.gmail.com with ESMTPSA id u11sm1490407qtk.61.2020.10.23.11.34.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Oct 2020 11:34:09 -0700 (PDT) From: Peter Xu To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Sean Christopherson , peterx@redhat.com, Andrew Jones , "Dr . David Alan Gilbert" , Paolo Bonzini Subject: [PATCH v15 06/14] KVM: Make dirty ring exclusive to dirty bitmap log Date: Fri, 23 Oct 2020 14:33:50 -0400 Message-Id: <20201023183358.50607-7-peterx@redhat.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201023183358.50607-1-peterx@redhat.com> References: <20201023183358.50607-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There's no good reason to use both the dirty bitmap logging and the new dirty ring buffer to track dirty bits. We should be able to even support both of them at the same time, but it could complicate things which could actually help little. Let's simply make it the rule before we enable dirty ring on any arch, that we don't allow these two interfaces to be used together. The big world switch would be KVM_CAP_DIRTY_LOG_RING capability enablement. That's where we'll switch from the default dirty logging way to the dirty ring way. As long as kvm->dirty_ring_size is setup correctly, we'll once and for all switch to the dirty ring buffer mode for the current virtual machine. Signed-off-by: Peter Xu --- Documentation/virt/kvm/api.rst | 7 +++++++ virt/kvm/kvm_main.c | 12 ++++++++++++ 2 files changed, 19 insertions(+) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 00da3f01d632..33e393759444 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6507,3 +6507,10 @@ make sure all the existing dirty gfns are flushed to the dirty rings. The dirty ring can gets full. When it happens, the KVM_RUN of the vcpu will return with exit reason KVM_EXIT_DIRTY_LOG_FULL. + +NOTE: the capability KVM_CAP_DIRTY_LOG_RING and the corresponding +ioctl KVM_RESET_DIRTY_RINGS are mutual exclusive to the existing ioctl +KVM_GET_DIRTY_LOG. After enabling KVM_CAP_DIRTY_LOG_RING with an +acceptable dirty ring size, the virtual machine will switch to the +dirty ring tracking mode. Further ioctls to either KVM_GET_DIRTY_LOG +or KVM_CLEAR_DIRTY_LOG will fail. diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 357b3f7b1127..c05b94696b21 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1426,6 +1426,10 @@ int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log, unsigned long n; unsigned long any = 0; + /* Dirty ring tracking is exclusive to dirty log tracking */ + if (kvm->dirty_ring_size) + return -EINVAL; + *memslot = NULL; *is_dirty = 0; @@ -1487,6 +1491,10 @@ static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log) unsigned long *dirty_bitmap_buffer; bool flush; + /* Dirty ring tracking is exclusive to dirty log tracking */ + if (kvm->dirty_ring_size) + return -EINVAL; + as_id = log->slot >> 16; id = (u16)log->slot; if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS) @@ -1595,6 +1603,10 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm, unsigned long *dirty_bitmap_buffer; bool flush; + /* Dirty ring tracking is exclusive to dirty log tracking */ + if (kvm->dirty_ring_size) + return -EINVAL; + as_id = log->slot >> 16; id = (u16)log->slot; if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS) -- 2.26.2