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([2601:646:c200:1ef2:e92e:2d95:2c68:42e6]) by smtp.gmail.com with ESMTPSA id m1sm267870pjv.22.2019.06.12.13.27.05 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 12 Jun 2019 13:27:06 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (1.0) Subject: Re: [RFC 00/10] Process-local memory allocations for hiding KVM secrets From: Andy Lutomirski X-Mailer: iPhone Mail (16F203) In-Reply-To: Date: Wed, 12 Jun 2019 13:27:04 -0700 Cc: Marius Hillenbrand , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, Alexander Graf , David Woodhouse , the arch/x86 maintainers , Andy Lutomirski , Peter Zijlstra Content-Transfer-Encoding: quoted-printable Message-Id: References: <20190612170834.14855-1-mhillenb@amazon.de> To: Dave Hansen 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: > On Jun 12, 2019, at 12:55 PM, Dave Hansen wrote: >=20 >> On 6/12/19 10:08 AM, Marius Hillenbrand wrote: >> This patch series proposes to introduce a region for what we call >> process-local memory into the kernel's virtual address space.=20 >=20 > It might be fun to cc some x86 folks on this series. They might have > some relevant opinions. ;) >=20 > A few high-level questions: >=20 > Why go to all this trouble to hide guest state like registers if all the > guest data itself is still mapped? >=20 > Where's the context-switching code? Did I just miss it? >=20 > We've discussed having per-cpu page tables where a given PGD is only in > use from one CPU at a time. I *think* this scheme still works in such a > case, it just adds one more PGD entry that would have to context-switched.= Fair warning: Linus is on record as absolutely hating this idea. He might ch= ange his mind, but it=E2=80=99s an uphill battle.=