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Tsirkin" To: Kuppuswamy Sathyanarayanan Subject: Re: [PATCH v5 16/16] x86/tdx: Add cmdline option to force use of ioremap_host_shared Message-ID: <20211009070132-mutt-send-email-mst@kernel.org> References: <20211009003711.1390019-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20211009003711.1390019-17-sathyanarayanan.kuppuswamy@linux.intel.com> MIME-Version: 1.0 In-Reply-To: <20211009003711.1390019-17-sathyanarayanan.kuppuswamy@linux.intel.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Cc: Kuppuswamy Sathyanarayanan , Peter Zijlstra , linux-pci@vger.kernel.org, linux-mips@vger.kernel.org, James E J Bottomley , Dave Hansen , Peter H Anvin , sparclinux@vger.kernel.org, Thomas Gleixner , Andrea Arcangeli , Andi Kleen , Jonathan Corbet , Helge Deller , x86@kernel.org, Ingo Molnar , linux-arch@vger.kernel.org, Arnd Bergmann , Tony Luck , Borislav Petkov , Andy Lutomirski , Josh Poimboeuf , Bjorn Helgaas , Dan Williams , virtualization@lists.linux-foundation.org, Richard Henderson , Thomas Bogendoerfer , linux-parisc@vger.kernel.org, Sean Christopherson , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, Paolo Bonzini , "David S . Miller" , Kirill Shutemov X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On Fri, Oct 08, 2021 at 05:37:11PM -0700, Kuppuswamy Sathyanarayanan wrote: > + ioremap_force_shared= [X86_64, CCG] > + Force the kernel to use shared memory mappings which do > + not use ioremap_host_shared/pcimap_host_shared to opt-in > + to shared mappings with the host. This feature is mainly > + used by a confidential guest when enabling new drivers > + without proper shared memory related changes. Please note > + that this option might also allow other non explicitly > + enabled drivers to interact with the host in confidential > + guest, which could cause other security risks. This option > + will also cause BIOS data structures to be shared with the > + host, which might open security holes. > + > io7= [HW] IO7 for Marvel-based Alpha systems > See comment before marvel_specify_io7 in > arch/alpha/kernel/core_marvel.c. The connection is quite unfortunate IMHO. Can't there be an option that unbreaks drivers *without* opening up security holes by making BIOS shared? -- MST _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization