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Tsirkin" To: Andi Kleen Cc: Kuppuswamy Sathyanarayanan , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Peter Zijlstra , Andy Lutomirski , Bjorn Helgaas , Richard Henderson , Thomas Bogendoerfer , James E J Bottomley , Helge Deller , "David S . Miller" , Arnd Bergmann , Jonathan Corbet , Paolo Bonzini , David Hildenbrand , Andrea Arcangeli , Josh Poimboeuf , Peter H Anvin , Dave Hansen , Tony Luck , Dan Williams , Kirill Shutemov , Sean Christopherson , Kuppuswamy Sathyanarayanan , x86@kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-alpha@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH v5 16/16] x86/tdx: Add cmdline option to force use of ioremap_host_shared Message-ID: <20211011142330-mutt-send-email-mst@kernel.org> References: <20211009003711.1390019-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20211009003711.1390019-17-sathyanarayanan.kuppuswamy@linux.intel.com> <20211009070132-mutt-send-email-mst@kernel.org> <8c906de6-5efa-b87a-c800-6f07b98339d0@linux.intel.com> <20211011075945-mutt-send-email-mst@kernel.org> <9d0ac556-6a06-0f2e-c4ff-0c3ce742a382@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9d0ac556-6a06-0f2e-c4ff-0c3ce742a382@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 11, 2021 at 10:35:18AM -0700, Andi Kleen wrote: > > > Presumably bios code is in arch/x86 and drivers/acpi, right? > > Up to 200 calls the majority of which is likely private ... > > Yes. > > > I don't have better ideas but the current setup will just > > result in people making their guests vulnerable whenever they > > want to allow device pass-through. > > > Yes that's true. For current TDX our target is virtual devices only. But if > pass through usage will be really wide spread we may need to revisit. > > > -Andi I mean ... it's already wide spread. If we support it with TDX it will be used with TDX. If we don't then I guess it won't, exposing this kind of limitation in a userspace visible way isn't great though. I guess it boils down to the fact that ioremap_host_shared is just not a great interface, users simply have no idea whether a given driver uses ioremap. -- MST