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[213.95.11.211]) by mx.google.com with ESMTPS id j18si9671933wrb.415.2019.08.10.03.58.22 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 10 Aug 2019 03:58:22 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of hch@lst.de designates 213.95.11.211 as permitted sender) client-ip=213.95.11.211; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of hch@lst.de designates 213.95.11.211 as permitted sender) smtp.mailfrom=hch@lst.de Received: by verein.lst.de (Postfix, from userid 2407) id D73C868BFE; Sat, 10 Aug 2019 12:58:19 +0200 (CEST) Date: Sat, 10 Aug 2019 12:58:19 +0200 From: Christoph Hellwig To: Bharata B Rao Cc: linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org, linux-mm@kvack.org, paulus@au1.ibm.com, aneesh.kumar@linux.vnet.ibm.com, jglisse@redhat.com, linuxram@us.ibm.com, sukadev@linux.vnet.ibm.com, cclaudio@linux.ibm.com, hch@lst.de Subject: Re: [PATCH v6 1/7] kvmppc: Driver to manage pages of secure guest Message-ID: <20190810105819.GA26030@lst.de> References: <20190809084108.30343-1-bharata@linux.ibm.com> <20190809084108.30343-2-bharata@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190809084108.30343-2-bharata@linux.ibm.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > +#ifdef CONFIG_PPC_UV > +extern unsigned long kvmppc_h_svm_page_in(struct kvm *kvm, > + unsigned long gra, > + unsigned long flags, > + unsigned long page_shift); > +extern unsigned long kvmppc_h_svm_page_out(struct kvm *kvm, > + unsigned long gra, > + unsigned long flags, > + unsigned long page_shift); No need for externs on function declarations. > +struct kvmppc_devm_device { > + struct device dev; > + dev_t devt; > + struct dev_pagemap pagemap; > + unsigned long pfn_first, pfn_last; > + unsigned long *pfn_bitmap; > +}; We shouldn't really need this conaining structucture given that there is only a single global instance of it anyway. > +struct kvmppc_devm_copy_args { > + unsigned long *rmap; > + unsigned int lpid; > + unsigned long gpa; > + unsigned long page_shift; > +}; Do we really need this args structure? It is just used in a single function call where passing the arguments might be cleaner. > +static void kvmppc_devm_put_page(struct page *page) > +{ > + unsigned long pfn = page_to_pfn(page); > + unsigned long flags; > + struct kvmppc_devm_page_pvt *pvt; > + > + spin_lock_irqsave(&kvmppc_devm_lock, flags); > + pvt = (struct kvmppc_devm_page_pvt *)page->zone_device_data; No need for the cast. > + page->zone_device_data = 0; This should be NULL. > + > + bitmap_clear(kvmppc_devm.pfn_bitmap, > + pfn - kvmppc_devm.pfn_first, 1); > + *(pvt->rmap) = 0; No need for the braces. > + dpage = alloc_page_vma(GFP_HIGHUSER, mig->vma, mig->start); > + if (!dpage) > + return -EINVAL; > + lock_page(dpage); > + pvt = (struct kvmppc_devm_page_pvt *)spage->zone_device_data; No need for the cast here. > +static void kvmppc_devm_page_free(struct page *page) > +{ > + kvmppc_devm_put_page(page); > +} This seems to be the only caller of kvmppc_devm_put_page, any reason not to just merge the two functions? > +static int kvmppc_devm_pages_init(void) > +{ > + unsigned long nr_pfns = kvmppc_devm.pfn_last - > + kvmppc_devm.pfn_first; > + > + kvmppc_devm.pfn_bitmap = kcalloc(BITS_TO_LONGS(nr_pfns), > + sizeof(unsigned long), GFP_KERNEL); > + if (!kvmppc_devm.pfn_bitmap) > + return -ENOMEM; > + > + spin_lock_init(&kvmppc_devm_lock); Just initialize the spinlock using DEFINE_SPINLOCK() at compile time. The rest of the function is so trivial that it can be inlined into the caller. Also is kvmppc_devm_lock such a good name? This mostly just protects the allocation bitmap, so reflecting that in the name might be a good idea. > +int kvmppc_devm_init(void) > +{ > + int ret = 0; > + unsigned long size; > + struct resource *res; > + void *addr; > + > + size = kvmppc_get_secmem_size(); > + if (!size) { > + ret = -ENODEV; > + goto out; > + } > + > + ret = alloc_chrdev_region(&kvmppc_devm.devt, 0, 1, > + "kvmppc-devm"); > + if (ret) > + goto out; > + > + dev_set_name(&kvmppc_devm.dev, "kvmppc_devm_device%d", 0); > + kvmppc_devm.dev.release = kvmppc_devm_release; > + device_initialize(&kvmppc_devm.dev); > + res = devm_request_free_mem_region(&kvmppc_devm.dev, > + &iomem_resource, size); > + if (IS_ERR(res)) { > + ret = PTR_ERR(res); > + goto out_unregister; > + } > + > + kvmppc_devm.pagemap.type = MEMORY_DEVICE_PRIVATE; > + kvmppc_devm.pagemap.res = *res; > + kvmppc_devm.pagemap.ops = &kvmppc_devm_ops; > + addr = devm_memremap_pages(&kvmppc_devm.dev, &kvmppc_devm.pagemap); > + if (IS_ERR(addr)) { > + ret = PTR_ERR(addr); > + goto out_unregister; > + } It seems a little silly to allocate a struct device just so that we can pass it to devm_request_free_mem_region and devm_memremap_pages. I think we should just create non-dev_ versions of those as well. > + > + kvmppc_devm.pfn_first = res->start >> PAGE_SHIFT; > + kvmppc_devm.pfn_last = kvmppc_devm.pfn_first + > + (resource_size(res) >> PAGE_SHIFT); pfn_last is only used to calculat a size. Also I think we could just use kvmppc_devm.pagemap.res directly instead of copying these values out. the ">> PAGE_SHIFT" is cheap enough.