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Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H . J . Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V . Shankar" , Weijiang Yang , "Kirill A . Shutemov" , joao.moreira@intel.com, John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com, Yu-cheng Yu Subject: Re: [PATCH v2 03/39] x86/cpufeatures: Add CPU feature flags for shadow stacks Message-ID: References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-4-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220929222936.14584-4-rick.p.edgecombe@intel.com> ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=temperror ("DNS error when getting key") header.d=alien8.de header.s=dkim header.b=ph9EsHV1; spf=temperror (imf15.hostedemail.com: error in processing during lookup of bp@alien8.de: DNS error) smtp.mailfrom=bp@alien8.de; dmarc=temperror reason="server fail" header.from=alien8.de (policy=temperror) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665764457; a=rsa-sha256; cv=none; b=E1P+CNmlqWU3zff8Myz4c5uq318BuhSJWTVoPT8b4uEyQSaEP1Pz+pi/WiQIKPgIukRBcu hUHGYp8HVeylSGFvq6w1NupYu0nAQJF65PYr/IZ8SlFhPF+5S0h8OXNACXxECLhax8eHyR C/2wr9YYv2MnlTM3PMZM+tR1m654B3Q= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1665764457; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=/Wh0zbFGTIbft2gDvKR16DzRYnJEB/RKZdQTzdqS+mY=; b=q19Ilfw04wD3OdiKvAvfONd88z+9ToIT+yZeLVtGZKGEx3xVUy62zjNF/MlNaw8VnjpY6O HjGx0gNb0ZADRJ4oHVLfHj25pn4z1ABp2vUIlM4DakodIU65nZpkUZvBZbZgr8Bz9R9rDQ DaGXzn+tpD1tKC22BF/12caHz+wvQ2o= X-Rspamd-Queue-Id: 1B943A002D X-Rspam-User: Authentication-Results: imf15.hostedemail.com; dkim=temperror ("DNS error when getting key") header.d=alien8.de header.s=dkim header.b=ph9EsHV1; spf=temperror (imf15.hostedemail.com: error in processing during lookup of bp@alien8.de: DNS error) smtp.mailfrom=bp@alien8.de; dmarc=temperror reason="server fail" header.from=alien8.de (policy=temperror) X-Rspamd-Server: rspam04 X-Stat-Signature: emrwe1j5c5eo8haa5iguuo3qwt9ewwr8 X-HE-Tag: 1665764449-351326 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 Thu, Sep 29, 2022 at 03:29:00PM -0700, Rick Edgecombe wrote: > From: Yu-cheng Yu > > The Control-Flow Enforcement Technology contains two related features, > one of which is Shadow Stacks. Future patches will utilize this feature > for shadow stack support in KVM, so add a CPU feature flags for Shadow > Stacks (CPUID.(EAX=7,ECX=0):ECX[bit 7]). > > To protect shadow stack state from malicious modification, the registers > are only accessible in supervisor mode. This implementation > context-switches the registers with XSAVES. Make X86_FEATURE_SHSTK depend > on XSAVES. > > Signed-off-by: Yu-cheng Yu > Co-developed-by: Rick Edgecombe > Signed-off-by: Rick Edgecombe > Cc: Kees Cook Reviewed-by: Borislav Petkov -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette