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[192.55.52.120]) by mx.google.com with ESMTPS id f59si526317plb.107.2019.06.12.12.55.39 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 12 Jun 2019 12:55:39 -0700 (PDT) Received-SPF: pass (google.com: domain of dave.hansen@intel.com designates 192.55.52.120 as permitted sender) client-ip=192.55.52.120; Authentication-Results: mx.google.com; spf=pass (google.com: domain of dave.hansen@intel.com designates 192.55.52.120 as permitted sender) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Jun 2019 12:55:38 -0700 X-ExtLoop1: 1 Received: from ray.jf.intel.com (HELO [10.7.198.156]) ([10.7.198.156]) by orsmga007.jf.intel.com with ESMTP; 12 Jun 2019 12:55:38 -0700 Subject: Re: [RFC 00/10] Process-local memory allocations for hiding KVM secrets To: Marius Hillenbrand , kvm@vger.kernel.org Cc: 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 References: <20190612170834.14855-1-mhillenb@amazon.de> From: Dave Hansen Openpgp: preference=signencrypt Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190612170834.14855-1-mhillenb@amazon.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit 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 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. It might be fun to cc some x86 folks on this series. They might have some relevant opinions. ;) A few high-level questions: Why go to all this trouble to hide guest state like registers if all the guest data itself is still mapped? Where's the context-switching code? Did I just miss it? 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.