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Tue, 13 Jan 2026 05:28:55 -0500 (EST) Date: Tue, 13 Jan 2026 10:28:50 +0000 From: Kiryl Shutsemau To: "Pratik R. 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, ardb@kernel.org, akpm@linux-foundation.org, david@kernel.org, osalvador@suse.de, thomas.lendacky@amd.com, michael.roth@amd.com Subject: Re: [PATCH v2 2/2] mm/memory_hotplug: Add support to unaccept memory after hot-remove Message-ID: References: <20260112202300.43546-1-prsampat@amd.com> <20260112202300.43546-3-prsampat@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260112202300.43546-3-prsampat@amd.com> X-Stat-Signature: cfe3wzrb3np7jyqswramqmfuw14scw9t X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 1B401100008 X-Rspam-User: X-HE-Tag: 1768300138-165943 X-HE-Meta: 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 4swnQXLT 021IT9/+tdE3iTyFAMArbGgCdIbuvkopUo0+QSGJy953LgD6VskHHSdYwU7miFRBC2qVQ6v40zfIlU1qLNhTgaYPZE95ecMBZfn6uvI9B5lNinnwak1Ehah7lmZkO3xir5Jb21pOzIbhe7l1kBDJVVD0pX+poGFXdQb3WazIx4JsfElP7ywxmx+bCfVEvopUrNQzszC26IoNAEb06NW2hA7iwxu7i41vdRAcKha2uHZFEZAyIfjeI70U6MSOIZSbemm77Mf7aSxdZIL+d06mwIq42v3AQMvck0ZYqgMBTdrEAfenKrvo5ZXiM1RVKAo/flCM0 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, Jan 12, 2026 at 02:23:00PM -0600, Pratik R. Sampat wrote: > Transition memory to the shared state during a hot-remove operation so > that it can be re-used by the hypervisor. This also applies when memory > is intended to be hotplugged back in later, as those pages will need to > be re-accepted after crossing the trust boundary. Hm. What happens when we hot-remove memory that was there at the boot and there's bitmap space for it? Also, I'm not sure why it is needed. At least in TDX case, VMM can pull the memory from under guest at any time without a warning. Coverting memory to shared shouldn't make a difference as along as re-adding the same GPA range triggers accept. -- Kiryl Shutsemau / Kirill A. Shutemov