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Sampat" Cc: linux-mm@kvack.org, linux-coco@lists.linux.dev, x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, kas@kernel.org, ardb@kernel.org, david@kernel.org, osalvador@suse.de, thomas.lendacky@amd.com, michael.roth@amd.com Subject: Re: [PATCH v2 1/2] mm/memory_hotplug: Add support to accept memory during hot-add Message-Id: <20260112144314.69b850afad9ee67143f30a85@linux-foundation.org> In-Reply-To: <2f9b180b-c221-4631-93d0-c131332ef178@amd.com> References: <20260112202300.43546-1-prsampat@amd.com> <20260112202300.43546-2-prsampat@amd.com> <20260112130401.a857fac6abcf104ea9bb5c68@linux-foundation.org> <2f9b180b-c221-4631-93d0-c131332ef178@amd.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: fjr5huoyxsb6318bxemjym9ijo4cypc4 X-Rspamd-Queue-Id: B1C8D20008 X-Rspamd-Server: rspam04 X-HE-Tag: 1768257796-195818 X-HE-Meta: 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 3lUbFEqk kuaE7EGgegk8zquQnHmogBG75sKfMF6Rehj+qTmrBMgKelugOioX69WScmqtog6xUjdBsXN+RXURMCmOT4oK2oT6z5LeJNp6rWirWIfWkwVXj7VDtS05V7q8P11vwVPuRWYbMZFvy6ddj17g18/V0kScCYWJGEujhHbyuaF6d5JauG1hNkRZ1tJF//UYsvAaoTd/QmqNx6wveSIBs3LYMW9LRie38nc+/0gt0RI229IFy7MnCvtuxpX3AifzRhmbCkGRO3PhKkpNHJcBHzBT9R2GvdzUsxOSxsw3OSliydrOAZku4lS/HbjLuAgHBWvfcWZofUo4IxAYrBYO5Y3FT1rZXueOUnyQ2971S 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: List-Subscribe: List-Unsubscribe: On Mon, 12 Jan 2026 16:23:37 -0600 "Pratik R. Sampat" wrote: > > > On 1/12/26 3:04 PM, Andrew Morton wrote: > > On Mon, 12 Jan 2026 14:22:59 -0600 "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 > > > > This only exists for x86! > > Ah, I missed that entirely. Thanks for catching that. > > Probably not the best option to have a generic unaccepted_memory.h as well. > Maybe, I should have arch_[un]accept_memory() definitions within mm.h wrapped > within CONFIG_UNACCEPTED_MEMORY instead so that its cleaner. Something like that. The idiomatic Linus way is to use #ifndef arch_accept_memory #define arch_accept_memory ... #endif Lots of prior art here: grep -r include/linux "ifndef arch_" Oh, arch_get_idle_state_flags() got it all wrong. #ifdef CONFIG_ACPI_PROCESSOR_IDLE #ifndef arch_get_idle_state_flags static inline unsigned int arch_get_idle_state_flags(u32 arch_flags) { return 0; } #endif #endif /* CONFIG_ACPI_PROCESSOR_IDLE */ - shouldn't have needed "ifdef CONFIG_ACPI_PROCESSOR_IDLE" - should have appended #define arch_get_idle_state_flags arch_get_idle_state_flags in case cpp hit the same lines a second time.