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Thu, 06 Feb 2020 12:02:04 -0800 (PST) Received: from xz-x1 ([2607:9880:19c8:32::2]) by smtp.gmail.com with ESMTPSA id k50sm163595qtc.90.2020.02.06.12.02.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Feb 2020 12:02:03 -0800 (PST) Date: Thu, 6 Feb 2020 15:02:00 -0500 From: Peter Xu To: Sean Christopherson Subject: Re: [PATCH v5 15/19] KVM: Provide common implementation for generic dirty log functions Message-ID: <20200206200200.GC700495@xz-x1> References: <20200121223157.15263-1-sean.j.christopherson@intel.com> <20200121223157.15263-16-sean.j.christopherson@intel.com> MIME-Version: 1.0 In-Reply-To: <20200121223157.15263-16-sean.j.christopherson@intel.com> X-MC-Unique: tYV4k9XsNASDRioDuPbvcA-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Cc: Wanpeng Li , kvm@vger.kernel.org, David Hildenbrand , linux-mips@vger.kernel.org, Paul Mackerras , kvmarm@lists.cs.columbia.edu, Janosch Frank , Marc Zyngier , Joerg Roedel , Christian Borntraeger , kvm-ppc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jim Mattson , Cornelia Huck , linux-kernel@vger.kernel.org, Paolo Bonzini , Vitaly Kuznetsov , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Tue, Jan 21, 2020 at 02:31:53PM -0800, Sean Christopherson wrote: [...] > -int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm, struct kvm_clear_dirty_log *log) > +void kvm_arch_dirty_log_tlb_flush(struct kvm *kvm, > + struct kvm_memory_slot *memslot) If it's to flush TLB for a memslot, shall we remove the "dirty_log" in the name of the function, because it has nothing to do with dirty logging any more? And... > { > - struct kvm_memslots *slots; > - struct kvm_memory_slot *memslot; > - bool flush = false; > - int r; > - > - mutex_lock(&kvm->slots_lock); > - > - r = kvm_clear_dirty_log_protect(kvm, log, &flush); > - > - if (flush) { > - slots = kvm_memslots(kvm); > - memslot = id_to_memslot(slots, log->slot); > - > - /* Let implementation handle TLB/GVA invalidation */ > - kvm_mips_callbacks->flush_shadow_memslot(kvm, memslot); > - } > - > - mutex_unlock(&kvm->slots_lock); > - return r; > + /* Let implementation handle TLB/GVA invalidation */ > + kvm_mips_callbacks->flush_shadow_memslot(kvm, memslot); ... This may not directly related to the current patch, but I'm confused on why MIPS cannot use kvm_flush_remote_tlbs() to flush TLBs. I know nothing about MIPS code, but IIUC here flush_shadow_memslot() is a heavier operation that will also invalidate the shadow pages. Seems to be an overkill here when we only changed write permission of the PTEs? I tried to check the first occurance (2a31b9db15353) but I didn't find out any clue of it so far. But that matters to this patch because if MIPS can use kvm_flush_remote_tlbs(), then we probably don't need this arch-specific hook any more and we can directly call kvm_flush_remote_tlbs() after sync dirty log when flush==true. > } > > long kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) > diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c > index 97ce6c4f7b48..0adaf4791a6d 100644 > --- a/arch/powerpc/kvm/book3s.c > +++ b/arch/powerpc/kvm/book3s.c > @@ -799,6 +799,11 @@ int kvmppc_core_check_requests(struct kvm_vcpu *vcpu) > return vcpu->kvm->arch.kvm_ops->check_requests(vcpu); > } > > +void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) Since at it, maybe we can start to use __weak attribute for new hooks especially when it's empty for most archs? E.g., define: void __weak kvm_arch_sync_dirty_log(...) {} In the common code, then only define it again in arch that has non-empty implementation of this method? -- Peter Xu _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm