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Tue, 03 Jun 2025 04:22:22 -0700 (PDT) Message-ID: Date: Tue, 3 Jun 2025 14:22:20 +0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 03/20] x86/virt/seamldr: Introduce a wrapper for P-SEAMLDR SEAMCALLs To: Chao Gao , linux-coco@lists.linux.dev, x86@kernel.org, kvm@vger.kernel.org Cc: seanjc@google.com, pbonzini@redhat.com, eddie.dong@intel.com, kirill.shutemov@intel.com, dave.hansen@intel.com, dan.j.williams@intel.com, kai.huang@intel.com, isaku.yamahata@intel.com, elena.reshetova@intel.com, rick.p.edgecombe@intel.com, Farrah Chen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , "Kirill A. Shutemov" , linux-kernel@vger.kernel.org References: <20250523095322.88774-1-chao.gao@intel.com> <20250523095322.88774-4-chao.gao@intel.com> From: Nikolay Borisov Content-Language: en-US Autocrypt: addr=nik.borisov@suse.com; keydata= xsFNBGcrpvIBEAD5cAR5+qu30GnmPrK9veWX5RVzzbgtkk9C/EESHy9Yz0+HWgCVRoNyRQsZ 7DW7vE1KhioDLXjDmeu8/0A8u5nFMqv6d1Gt1lb7XzSAYw7uSWXLPEjFBtz9+fBJJLgbYU7G OpTKy6gRr6GaItZze+r04PGWjeyVUuHZuncTO7B2huxcwIk9tFtRX21gVSOOC96HcxSVVA7X N/LLM2EOL7kg4/yDWEhAdLQDChswhmdpHkp5g6ytj9TM8bNlq9I41hl/3cBEeAkxtb/eS5YR 88LBb/2FkcGnhxkGJPNB+4Siku7K8Mk2Y6elnkOctJcDvk29DajYbQnnW4nhfelZuLNupb1O M0912EvzOVI0dIVgR+xtosp66bYTOpX4Xb0fylED9kYGiuEAeoQZaDQ2eICDcHPiaLzh+6cc pkVTB0sXkWHUsPamtPum6/PgWLE9vGI5s+FaqBaqBYDKyvtJfLK4BdZng0Uc3ijycPs3bpbQ bOnK9LD8TYmYaeTenoNILQ7Ut54CCEXkP446skUMKrEo/HabvkykyWqWiIE/UlAYAx9+Ckho TT1d2QsmsAiYYWwjU8igXBecIbC0uRtF/cTfelNGrQwbICUT6kJjcOTpQDaVyIgRSlUMrlNZ XPVEQ6Zq3/aENA8ObhFxE5PLJPizJH6SC89BMKF3zg6SKx0qzQARAQABzSZOaWtvbGF5IEJv cmlzb3YgPG5pay5ib3Jpc292QHN1c2UuY29tPsLBkQQTAQoAOxYhBDuWB8EJLBUZCPjT3SRn XZEnyhfsBQJnK6byAhsDBQsJCAcCAiICBhUKCQgLAgQWAgMBAh4HAheAAAoJECRnXZEnyhfs XbIQAJxuUnelGdXbSbtovBNm+HF3LtT0XnZ0+DoR0DemUGuA1bZAlaOXGr5mvVbTgaoGUQIJ 3Ejx3UBEG7ZSJcfJobB34w1qHEDO0pN9orGIFT9Bic3lqhawD2r85QMcWwjsZH5FhyRx7P2o DTuUClLMO95GuHYQngBF2rHHl8QMJPVKsR18w4IWAhALpEApxa3luyV7pAAqKllfCNt7tmed uKmclf/Sz6qoP75CvEtRbfAOqYgG1Uk9A62C51iAPe35neMre3WGLsdgyMj4/15jPYi+tOUX Tc7AAWgc95LXyPJo8069MOU73htZmgH4OYy+S7f+ArXD7h8lTLT1niff2bCPi6eiAQq6b5CJ Ka4/27IiZo8tm1XjLYmoBmaCovqx5y5Xt2koibIWG3ZGD2I+qRwZ0UohKRH6kKVHGcrmCv0J YO8yIprxgoYmA7gq21BpTqw3D4+8xujn/6LgndLKmGESM1FuY3ymXgj5983eqaxicKpT9iq8 /a1j31tms4azR7+6Dt8H4SagfN6VbJ0luPzobrrNFxUgpjR4ZyQQ++G7oSRdwjfIh1wuCF6/ mDUNcb6/kA0JS9otiC3omfht47yQnvod+MxFk1lTNUu3hePJUwg1vT1te3vO5oln8lkUo9BU knlYpQ7QA2rDEKs+YWqUstr4pDtHzwQ6mo0rqP+zzsFNBGcrpvIBEADGYTFkNVttZkt6e7yA LNkv3Q39zQCt8qe7qkPdlj3CqygVXfw+h7GlcT9fuc4kd7YxFys4/Wd9icj9ZatGMwffONmi LnUotIq2N7+xvc4Xu76wv+QJpiuGEfCDB+VdZOmOzUPlmMkcJc/EDSH4qGogIYRu72uweKEq VfBI43PZIGpGJ7TjS3THX5WVI2YNSmuwqxnQF/iVqDtD2N72ObkBwIf9GnrOgxEyJ/SQq2R0 g7hd6IYk7SOKt1a8ZGCN6hXXKzmM6gHRC8fyWeTqJcK4BKSdX8PzEuYmAJjSfx4w6DoxdK5/ 9sVrNzaVgDHS0ThH/5kNkZ65KNR7K2nk45LT5Crjbg7w5/kKDY6/XiXDx7v/BOR/a+Ryo+lM MffN3XSnAex8cmIhNINl5Z8CAvDLUtItLcbDOv7hdXt6DSyb65CdyY8JwOt6CWno1tdjyDEG 5ANwVPYY878IFkOJLRTJuUd5ltybaSWjKIwjYJfIXuoyzE7OL63856MC/Os8PcLfY7vYY2LB cvKH1qOcs+an86DWX17+dkcKD/YLrpzwvRMur5+kTgVfXcC0TAl39N4YtaCKM/3ugAaVS1Mw MrbyGnGqVMqlCpjnpYREzapSk8XxbO2kYRsZQd8J9ei98OSqgPf8xM7NCULd/xaZLJUydql1 JdSREId2C15jut21aQARAQABwsF2BBgBCgAgFiEEO5YHwQksFRkI+NPdJGddkSfKF+wFAmcr pvICGwwACgkQJGddkSfKF+xuuxAA4F9iQc61wvAOAidktv4Rztn4QKy8TAyGN3M8zYf/A5Zx VcGgX4J4MhRUoPQNrzmVlrrtE2KILHxQZx5eQyPgixPXri42oG5ePEXZoLU5GFRYSPjjTYmP ypyTPN7uoWLfw4TxJqWCGRLsjnkwvyN3R4161Dty4Uhzqp1IkNhl3ifTDYEvbnmHaNvlvvna 7+9jjEBDEFYDMuO/CA8UtoVQXjy5gtOhZZkEsptfwQYc+E9U99yxGofDul7xH41VdXGpIhUj 4wjd3IbgaCiHxxj/M9eM99ybu5asvHyMo3EFPkyWxZsBlUN/riFXGspG4sT0cwOUhG2ZnExv XXhOGKs/y3VGhjZeCDWZ+0ZQHPCL3HUebLxW49wwLxvXU6sLNfYnTJxdqn58Aq4sBXW5Un0Q vfbd9VFV/bKFfvUscYk2UKPi9vgn1hY38IfmsnoS8b0uwDq75IBvup9pYFyNyPf5SutxhFfP JDjakbdjBoYDWVoaPbp5KAQ2VQRiR54lir/inyqGX+dwzPX/F4OHfB5RTiAFLJliCxniKFsM d8eHe88jWjm6/ilx4IlLl9/MdVUGjLpBi18X7ejLz3U2quYD8DBAGzCjy49wJ4Di4qQjblb2 pTXoEyM2L6E604NbDu0VDvHg7EXh1WwmijEu28c/hEB6DwtzslLpBSsJV0s1/jE= In-Reply-To: <20250523095322.88774-4-chao.gao@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 5/23/25 12:52, Chao Gao wrote: > P-SEAMLDR is another component alongside the TDX module within the > protected SEAM range. Software can invoke its functions by executing the > SEAMCALL instruction with the 63 bit of RAX set to 1. P-SEAMLDR SEAMCALLs > differ from those of the TDX module in terms of error codes and the > handling of the current VMCS. > > Add a wrapper for P-SEAMLDR SEAMCALLs based on the SEAMCALL infrastructure. > > Intel® Trust Domain CPU Architectural Extensions (May 2021 edition) > Chapter 2.3 states: > > SEAMRET from the P-SEAMLDR clears the current VMCS structure pointed to by > the current-VMCS pointer. A VMM that invokes the P-SEAMLDR using SEAMCALL > must reload the current-VMCS, if required, using the VMPTRLD instruction. > > So, save and restore the current-VMCS pointer using VMPTRST and VMPTRLD > instructions to avoid breaking KVM, which manages the current-VMCS. > > Disable interrupts to prevent KVM code from interfering with P-SEAMLDR > SEAMCALLs. For example, if a vCPU is scheduled before the current VMCS is > restored, it may encounter an invalid current VMCS, causing its VMX > instruction to fail. Additionally, if KVM sends IPIs to invalidate a > current VMCS and the invalidation occurs right after the current VMCS is > saved, that VMCS will be reloaded after P-SEAMLDR SEAMCALLs, leading to > unexpected behavior. > > NMIs are not a problem, as the only scenario where instructions relying on > the current-VMCS are used is during guest PMI handling in KVM. This occurs > immediately after VM exits with IRQ and NMI disabled, ensuring no > interference with P-SEAMLDR SEAMCALLs. > > Signed-off-by: Chao Gao > Tested-by: Farrah Chen > --- > arch/x86/Kconfig | 10 ++++++++ > arch/x86/virt/vmx/tdx/Makefile | 1 + > arch/x86/virt/vmx/tdx/seamldr.c | 44 +++++++++++++++++++++++++++++++++ > arch/x86/virt/vmx/vmx.h | 40 ++++++++++++++++++++++++++++++ > 4 files changed, 95 insertions(+) > create mode 100644 arch/x86/virt/vmx/tdx/seamldr.c > create mode 100644 arch/x86/virt/vmx/vmx.h > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 4b9f378e05f6..8b1e0986b7f8 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1932,6 +1932,16 @@ config INTEL_TDX_HOST > > If unsure, say N. > > +config INTEL_TDX_MODULE_UPDATE > + bool "Intel TDX module runtime update" > + depends on INTEL_TDX_HOST > + help > + This enables the kernel to support TDX module runtime update. This allows > + the admin to upgrade the TDX module to a newer one without the need to > + terminate running TDX guests. > + > + If unsure, say N. > + WHy should this be conditional?