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Wed, 01 Oct 2025 00:12:37 -0700 (PDT) MIME-Version: 1.0 References: <20250924-b4-asi-page-alloc-v1-0-2d861768041f@google.com> In-Reply-To: From: Brendan Jackman Date: Wed, 1 Oct 2025 09:12:25 +0200 X-Gm-Features: AS18NWAifHOvvZfxOYNmfg733w5HRL1kfD7yDfmp_AAQDacXW-pG953lY3cbh20 Message-ID: Subject: Re: [PATCH 00/21] mm: ASI direct map management To: Konrad Rzeszutek Wilk Cc: Andy Lutomirski , Lorenzo Stoakes , "Liam R. Howlett" , Suren Baghdasaryan , Michal Hocko , Johannes Weiner , Zi Yan , Axel Rasmussen , Yuanchu Xie , Roman Gushchin , peterz@infradead.org, bp@alien8.de, dave.hansen@linux.intel.com, mingo@redhat.com, tglx@linutronix.de, akpm@linux-foundation.org, david@redhat.com, derkling@google.com, junaids@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, reijiw@google.com, rientjes@google.com, rppt@kernel.org, vbabka@suse.cz, x86@kernel.org, Yosry Ahmed Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 62AF2C000C X-Rspamd-Server: rspam05 X-Stat-Signature: tqbteaex57bpa3idbnjcf6o5by77wp7r X-Rspam-User: X-HE-Tag: 1759302759-481468 X-HE-Meta: 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 OvTSsbM8 6RQk8Z/KSUCadl8lKCSbqNI67lrbe+GIVyw/R1YNw3R06zVbcDWihT01mK6ROv/oGCHv5qnN14bG2+Do2EenJzIdnwJJVXrR1H3PsQzr33aYiwBKMVjFyuVMV2lYzbPlTTooX27FhN+Tfd3VLKWx1CNwBx6FRuKOVWeLlub1ZAGifOlgBNVca3r7JFVEigGkhmEm6iU6O2oQ01n4S/w6jBRBjEa51vB5wUkwBxNQNN0bgh109mgb25+b9B6pZS8bd/8gTWhtP5f0sexI= 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 Tue, 30 Sept 2025 at 21:51, Konrad Rzeszutek Wilk wrote: > > On Wed, Sep 24, 2025 at 02:59:35PM +0000, Brendan Jackman wrote: > > As per [0] I think ASI is ready to start merging. This is the first > > step. The scope of this series is: everything needed to set up the > > direct map in the restricted address spaces. > > There looks to be a different approach taken by other folks to > yank the guest pages from the hypervisor: > > https://lore.kernel.org/kvm/20250912091708.17502-1-roypat@amazon.co.uk/ > > That looks to have a very similar end result with less changes? Hey Konrad, Yeah if you only care about the security boundary around VM guests, and you're able to rework your hypervisor stack appropriately (I don't know too much about this but presumably it's just a subset of what's needed to support confidential computing usecases?), that approach seems good to me. But that isn't true for most of Linux's users. We still need to support systems where there is a meaningful security boundary around native processes. Also, unless I'm mistaken Patrick's approach will always require changes to the VMM, I don't think the kernel can just tell all users to go and make those changes. Basically: I support that approach, it's a good idea. It just solves a different set of problems. (I haven't thought about it carefully but I guess it solves some problems that ASI doesn't, since I guess it prevents some set of software exploits too, while ASI only helps with HW vulns). Cheers, Brendan