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From: Erdem Aktas To: dave.hansen@intel.com Cc: almasrymina@google.com, dave.hansen@linux.intel.com, gthelen@google.com, jiaqiyan@google.com, juew@google.com, linux-mm@kvack.org, naoya.horiguchi@nec.com, seanjc@google.com, tony.luck@intel.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 03A1A40061 X-Stat-Signature: exj57w3dd99p7m8msgc7ompwzui1fcmr X-Rspam-User: Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=f88IeMvp; spf=pass (imf11.hostedemail.com: domain of 3uL1qYgoKCPcdqcdlZjsZrfnnfkd.bnlkhmtw-lljuZbj.nqf@flex--erdemaktas.bounces.google.com designates 209.85.210.201 as permitted sender) smtp.mailfrom=3uL1qYgoKCPcdqcdlZjsZrfnnfkd.bnlkhmtw-lljuZbj.nqf@flex--erdemaktas.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com X-HE-Tag: 1651162550-899876 X-Bogosity: Ham, tests=bogofilter, spamicity=0.089958, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > On 4/26/22 12:23, Jue Wang wrote: > > On Tue, Apr 26, 2022 at 11:18 AM Dave Hansen wrote: > I shouldn't speak for Intel as a whole, but I'll give you my personal > perspective. > > Right now, hosts can't scan TDX private memory, period. If you wanted > to do scanning, the guest has to do it or you have to kill the guest and > make the memory non-private. Actually, afaiu, the host can read tdx private memory. This should NOT generate #MC due to integrity/TD ownership but return a fixed value of "0"s. I do not know if this will also trigger #MCs due to memory errors. > > Going forward, guest memory scanning could be accomplished by allowing > the VMM to migrate guest pages. Let's say you want to scan page "A", > you could move A->B and B->A. That would certainly touch the page. > This would need to be implemented in the TDX module. TDH.MEM.PAGE.RELOCATE should be able to migrate guest pages but I am not sure if this would be feasible depending on how often we keep relocating pages.