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TDX architecture introduces the concept of private GPA vs shared GPA, depending on the GPA.SHARED bit. The TDX module maintains a single Secure EPT (S-EPT or SEPT) tree per TD to translate TD's private memory accessed using a private GPA. Wrap the SEAMCALL TDH.MEM.PAGE.REMOVE with tdh_mem_page_remove() and TDH_PHYMEM_PAGE_WBINVD with tdh_phymem_page_wbinvd_hkid() to unmap a TD private page from the SEPT, remove the TD private page from the TDX module and flush cache lines to memory after removal of the private page. Callers should specify "GPA" and "level" when calling tdh_mem_page_remove() to indicate to the TDX module which TD private page to unmap and remove. TDH.MEM.PAGE.REMOVE may fail, and the caller of tdh_mem_page_remove() can check the function return value and retrieve extended error information from the function output parameters. Follow the TLB tracking protocol before calling tdh_mem_page_remove() to remove a TD private page to avoid SEAMCALL failure. After removing a TD's private page, the TDX module does not write back and invalidate cache lines associated with the page and the page's keyID (i.e., the TD's guest keyID). Therefore, provide tdh_phymem_page_wbinvd_hkid() to allow the caller to pass in the TD's guest keyID and invoke TDH_PHYMEM_PAGE_WBINVD to perform this action. Before reusing the page, the host kernel needs to map the page with keyID 0 and invoke movdir64b() to convert the TD private page to a normal shared page. TDH.MEM.PAGE.REMOVE and TDH_PHYMEM_PAGE_WBINVD may meet contentions inside the TDX module for TDX's internal resources. To avoid staying in SEAM mode for too long, TDX module will return a BUSY error code to the kernel instead of spinning on the locks. The caller may need to handle this error in specific ways (e.g., retry). The wrappers return the SEAMCALL error code directly to the caller. Don't attempt to handle it in the core kernel. [Kai: Switched from generic seamcall export] [Yan: Re-wrote the changelog] Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com> Signed-off-by: Kai Huang <kai.huang@intel.com> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Signed-off-by: Yan Zhao <yan.y.zhao@intel.com> Message-ID: <20241112073658.22157-1-yan.y.zhao@intel.com> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.