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[2003:cb:c704:d800:887:cbec:f31f:a08]) by smtp.gmail.com with ESMTPSA id f13-20020a05600c4e8d00b003c6c182bef9sm11363749wmq.36.2022.11.25.01.28.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 25 Nov 2022 01:28:16 -0800 (PST) Message-ID: <361875cb-e4b3-a46f-b275-6d87a98ce966@redhat.com> Date: Fri, 25 Nov 2022 10:28:15 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.1 Subject: Re: [PATCH v7 10/20] x86/virt/tdx: Use all system memory when initializing TDX module as TDX memory Content-Language: en-US To: "Huang, Kai" , "Williams, Dan J" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" Cc: "Hansen, Dave" , "Luck, Tony" , "bagasdotme@gmail.com" , "ak@linux.intel.com" , "Wysocki, Rafael J" , "kirill.shutemov@linux.intel.com" , "Christopherson,, Sean" , "Chatre, Reinette" , "pbonzini@redhat.com" , "linux-mm@kvack.org" , "Yamahata, Isaku" , "peterz@infradead.org" , "Shahar, Sagi" , "imammedo@redhat.com" , "Gao, Chao" , "Brown, Len" , "sathyanarayanan.kuppuswamy@linux.intel.com" , "Huang, Ying" References: <9b545148275b14a8c7edef1157f8ec44dc8116ee.1668988357.git.kai.huang@intel.com> <637ecded7b0f9_160eb329418@dwillia2-xfh.jf.intel.com.notmuch> <8e8f72ad5d7a3d09be32bee54e4ebb9c280610a2.camel@intel.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <8e8f72ad5d7a3d09be32bee54e4ebb9c280610a2.camel@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24.11.22 10:06, Huang, Kai wrote: > On Wed, 2022-11-23 at 17:50 -0800, Dan Williams wrote: >>> >>> @@ -968,6 +969,15 @@ int arch_add_memory(int nid, u64 start, u64 size, >>>    unsigned long start_pfn = start >> PAGE_SHIFT; >>>    unsigned long nr_pages = size >> PAGE_SHIFT; >>> >>> + /* >>> + * For now if TDX is enabled, all pages in the page allocator >>> + * must be TDX memory, which is a fixed set of memory regions >>> + * that are passed to the TDX module.  Reject the new region >>> + * if it is not TDX memory to guarantee above is true. >>> + */ >>> + if (!tdx_cc_memory_compatible(start_pfn, start_pfn + nr_pages)) >>> + return -EINVAL; >> >> arch_add_memory() does not add memory to the page allocator.  For >> example, memremap_pages() uses arch_add_memory() and explicitly does not >> release the memory to the page allocator. > > Indeed. Sorry I missed this. > >> This check belongs in >> add_memory_resource() to prevent new memory that violates TDX from being >> onlined. > > This would require adding another 'arch_cc_memory_compatible()' to the common > add_memory_resource() (I actually long time ago had such patch to work with the > memremap_pages() you mentioned above). > > How about adding a memory_notifier to the TDX code, and reject online of TDX > incompatible memory (something like below)? The benefit is this is TDX code > self contained and won't pollute the common mm code: > > +static int tdx_memory_notifier(struct notifier_block *nb, > + unsigned long action, void *v) > +{ > + struct memory_notify *mn = v; > + > + if (action != MEM_GOING_ONLINE) > + return NOTIFY_OK; > + > + /* > + * Not all memory is compatible with TDX. Reject > + * online of any incompatible memory. > + */ > + return tdx_cc_memory_compatible(mn->start_pfn, > + mn->start_pfn + mn->nr_pages) ? NOTIFY_OK : NOTIFY_BAD; > +} > + > +static struct notifier_block tdx_memory_nb = { > + .notifier_call = tdx_memory_notifier, > +}; With mhp_memmap_on_memory() some memory might already be touched during add_memory() (because part of the hotplug memory is used for holding the memmap), not when actually onlining memory. So in that case, this would be too late. add_memory_resource() sounds better, even though I disgust such TDX special handling in common code. -- Thanks, David / dhildenb