From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BE04A35580A; Wed, 14 Jan 2026 10:30:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768386619; cv=none; b=pjI39sCC+fZQu/E6efagozeUUaWROVTK9xFh/CHpkPFy0ps628iKEI56lQh1BH3TeuV5ZtzhoYdpBwp2sTPk19BEIKRodEEAbUrBShymlHGc5UHJMwWPBWWbmxuwk9nzy3kv28McM8q9hHXbdnImov5g9qKSw1T/pQT3aF/JmJI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768386619; c=relaxed/simple; bh=77eN+I93e/xYMMtzRTv9G1YoYjUEH5vEbzp1mfa2DjI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=g4zB1X7OU4yWh6BwDiGnTxdAm+QY8zutFAcYgmsh1mySJ9rWtlOrpgW0b8CO+MI+LqvOuPg2Zs6I8P7sbpV8IEnt6jGydIUdfWSVHZGgV/7xmf30kGw/XpHMYrTmKY0s0Ijkn7Mms/ru+VgvZVz+JGwpLOMEFkJJvzM8F+EnN04= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DYfpyomb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DYfpyomb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BFE35C4CEF7; Wed, 14 Jan 2026 10:30:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768386619; bh=77eN+I93e/xYMMtzRTv9G1YoYjUEH5vEbzp1mfa2DjI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=DYfpyomb3EQk2nMVNlKn6qt/87F2u+pToxXfZxzOlMqt1ACFTaOF/IEsA0RV0VY6t ydoOkZBhkOW3zLWlGWxOVPy/IOJTlZoHr7CinQuPrYOnYWMrTBHFOR8S89l/G3zIZ0 XY9OkKqDpulpiqClfXz+HqUL6yu2/XzKZ+eE1Sd2KOcC0bhjUrEBkSfdL6T51u4DcO StZZxajFX0AiS0SO5spKL5MrJr2NIh91ihPGoqPTYxYafroL6lpa9FgG3gl1wfBB9B 6lxpMS1HMBojP8SJ9OUykFnKqRU3axu9Och9r34zxi+gub1WSbtF4Clv5X3QVMyleb tE5OZ0SRjjB2A== Message-ID: <4f2c6106-9cc1-4196-8b20-83b297ae7195@kernel.org> Date: Wed, 14 Jan 2026 11:30:13 +0100 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] mm/memory_hotplug: Add support to accept memory during hot-add To: "Pratik R. Sampat" , linux-mm@kvack.org, linux-coco@lists.linux.dev, x86@kernel.org, linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, kas@kernel.org, ardb@kernel.org, akpm@linux-foundation.org, osalvador@suse.de, thomas.lendacky@amd.com, michael.roth@amd.com References: <20260112202300.43546-1-prsampat@amd.com> <20260112202300.43546-2-prsampat@amd.com> From: "David Hildenbrand (Red Hat)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAa2VybmVsLm9yZz7CwY0EEwEIADcWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCaKYhwAIbAwUJJlgIpAILCQQVCgkIAhYCAh4FAheAAAoJEE3eEPcA/4Naa5EP/3a1 9sgS9m7oiR0uenlj+C6kkIKlpWKRfGH/WvtFaHr/y06TKnWn6cMOZzJQ+8S39GOteyCCGADh 6ceBx1KPf6/AvMktnGETDTqZ0N9roR4/aEPSMt8kHu/GKR3gtPwzfosX2NgqXNmA7ErU4puf zica1DAmTvx44LOYjvBV24JQG99bZ5Bm2gTDjGXV15/X159CpS6Tc2e3KvYfnfRvezD+alhF XIym8OvvGMeo97BCHpX88pHVIfBg2g2JogR6f0PAJtHGYz6M/9YMxyUShJfo0Df1SOMAbU1Q Op0Ij4PlFCC64rovjH38ly0xfRZH37DZs6kP0jOj4QdExdaXcTILKJFIB3wWXWsqLbtJVgjR YhOrPokd6mDA3gAque7481KkpKM4JraOEELg8pF6eRb3KcAwPRekvf/nYVIbOVyT9lXD5mJn IZUY0LwZsFN0YhGhQJ8xronZy0A59faGBMuVnVb3oy2S0fO1y/r53IeUDTF1wCYF+fM5zo14 5L8mE1GsDJ7FNLj5eSDu/qdZIKqzfY0/l0SAUAAt5yYYejKuii4kfTyLDF/j4LyYZD1QzxLC MjQl36IEcmDTMznLf0/JvCHlxTYZsF0OjWWj1ATRMk41/Q+PX07XQlRCRcE13a8neEz3F6we 08oWh2DnC4AXKbP+kuD9ZP6+5+x1H1zEzsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCgh Cj/CA/lc/LMthqQ773gauB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseB fDXHA6m4B3mUTWo13nid0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts 6TZ+IrPOwT1hfB4WNC+X2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiu Qmt3yqrmN63V9wzaPhC+xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKB Tccu2AXJXWAE1Xjh6GOC8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvF FFyAS0Nk1q/7EChPcbRbhJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh 2YmnmLRTro6eZ/qYwWkCu8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRk F3TwgucpyPtcpmQtTkWSgDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0L LH63+BrrHasfJzxKXzqgrW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4v q7oFCPsOgwARAQABwsF8BBgBCAAmAhsMFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAmic2qsF CSZYCKEACgkQTd4Q9wD/g1oq0xAAsAnw/OmsERdtdwRfAMpC74/++2wh9RvVQ0x8xXvoGJwZ rk0Jmck1ABIM//5sWDo7eDHk1uEcc95pbP9XGU6ZgeiQeh06+0vRYILwDk8Q/y06TrTb1n4n 7FRwyskKU1UWnNW86lvWUJuGPABXjrkfL41RJttSJHF3M1C0u2BnM5VnDuPFQKzhRRktBMK4 GkWBvXlsHFhn8Ev0xvPE/G99RAg9ufNAxyq2lSzbUIwrY918KHlziBKwNyLoPn9kgHD3hRBa Yakz87WKUZd17ZnPMZiXriCWZxwPx7zs6cSAqcfcVucmdPiIlyG1K/HIk2LX63T6oO2Libzz 7/0i4+oIpvpK2X6zZ2cu0k2uNcEYm2xAb+xGmqwnPnHX/ac8lJEyzH3lh+pt2slI4VcPNnz+ vzYeBAS1S+VJc1pcJr3l7PRSQ4bv5sObZvezRdqEFB4tUIfSbDdEBCCvvEMBgoisDB8ceYxO cFAM8nBWrEmNU2vvIGJzjJ/NVYYIY0TgOc5bS9wh6jKHL2+chrfDW5neLJjY2x3snF8q7U9G EIbBfNHDlOV8SyhEjtX0DyKxQKioTYPOHcW9gdV5fhSz5tEv+ipqt4kIgWqBgzK8ePtDTqRM qZq457g1/SXSoSQi4jN+gsneqvlTJdzaEu1bJP0iv6ViVf15+qHuY5iojCz8fa0= In-Reply-To: <20260112202300.43546-2-prsampat@amd.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/12/26 21:22, Pratik R. Sampat wrote: > Confidential computing guests require memory to be accepted before use. > The unaccepted memory bitmap maintained by firmware does not track > hotplugged memory ranges. > > Call arch_accept_memory() during the hot-add path to explicitly validate > and transition the newly added memory to a private state, making it > usable by the guest. > > Signed-off-by: Pratik R. Sampat > --- > mm/memory_hotplug.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index a63ec679d861..8cfbf0541430 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -38,6 +38,7 @@ > #include > > #include > +#include > > #include "internal.h" > #include "shuffle.h" > @@ -1567,6 +1568,9 @@ int add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags) > if (!strcmp(res->name, "System RAM")) > firmware_map_add_hotplug(start, start + size, "System RAM"); > > + if (IS_ENABLED(CONFIG_UNACCEPTED_MEMORY)) > + arch_accept_memory(start, start + size); > + > /* device_online() will take the lock when calling online_pages() */ > mem_hotplug_done(); > As discussed, for things like virtio-mem or the HV-balloon this might be the wrong thing to do, but I don't expect these mechanisms to be used in CoCo environments just yet (and doing so would require enabling work for them). So I'm fine with this for now. -- Cheers David