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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 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.ADD with tdh_mem_page_add() and TDH.MEM.PAGE.AUG with tdh_mem_page_aug() to add TD private pages and map them to the TD's private GPAs in the SEPT. Callers of tdh_mem_page_add() and tdh_mem_page_aug() allocate and provide normal pages to the wrappers, who further pass those pages to the TDX module. Before passing the pages to the TDX module, tdh_mem_page_add() and tdh_mem_page_aug() perform a CLFLUSH on the page mapped with keyID 0 to ensure that any dirty cache lines don't write back later and clobber TD memory or control structures. Don't worry about the other MK-TME keyIDs because the kernel doesn't use them. The TDX docs specify that this flush is not needed unless the TDX module exposes the CLFLUSH_BEFORE_ALLOC feature bit. Do the CLFLUSH unconditionally for two reasons: make the solution simpler by having a single path that can handle both !CLFLUSH_BEFORE_ALLOC and CLFLUSH_BEFORE_ALLOC cases. Avoid wading into any correctness uncertainty by going with a conservative solution to start. Call tdh_mem_page_add() to add a private page to a TD during the TD's build time (i.e., before TDH.MR.FINALIZE). Specify which GPA the 4K private page will map to. No need to specify level info since TDH.MEM.PAGE.ADD only adds pages at 4K level. To provide initial contents to TD, provide an additional source page residing in memory managed by the host kernel itself (encrypted with a shared keyID). The TDX module will copy the initial contents from the source page in shared memory into the private page after mapping the page in the SEPT to the specified private GPA. The TDX module allows the source page to be the same page as the private page to be added. In that case, the TDX module converts and encrypts the source page as a TD private page. Call tdh_mem_page_aug() to add a private page to a TD during the TD's runtime (i.e., after TDH.MR.FINALIZE). TDH.MEM.PAGE.AUG supports adding huge pages. Specify which GPA the private page will map to, along with level info embedded in the lower bits of the GPA. The TDX module will recognize the added page as the TD's private page after the TD's acceptance with TDCALL TDG.MEM.PAGE.ACCEPT. tdh_mem_page_add() and tdh_mem_page_aug() may fail. Callers can check function return value and retrieve extended error info from the function output parameters. The TDX module has many internal locks. To avoid staying in SEAM mode for too long, SEAMCALLs returns a BUSY error code to the kernel instead of spinning on the locks. Depending on the specific SEAMCALL, the caller may need to handle this error in specific ways (e.g., retry). Therefore, 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: <20241112073636.22129-1-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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| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
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| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
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| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
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| .mailmap | ||
| .rustfmt.toml | ||
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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.