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c641cfb5c1
Now the 'struct tdx_hypercall_args' and 'struct tdx_module_args' are almost the same, and the TDX_HYPERCALL and TDX_MODULE_CALL asm macro share similar code pattern too. The __tdx_hypercall() and __tdcall() should be unified to use the same assembly code. As a preparation to unify them, simplify the TDX_HYPERCALL to make it more like the TDX_MODULE_CALL. The TDX_HYPERCALL takes the pointer of 'struct tdx_hypercall_args' as function call argument, and does below extra things comparing to the TDX_MODULE_CALL: 1) It sets RAX to 0 (TDG.VP.VMCALL leaf) internally; 2) It sets RCX to the (fixed) bitmap of shared registers internally; 3) It calls __tdx_hypercall_failed() internally (and panics) when the TDCALL instruction itself fails; 4) After TDCALL, it moves R10 to RAX to return the return code of the VMCALL leaf, regardless the '\ret' asm macro argument; Firstly, change the TDX_HYPERCALL to take the same function call arguments as the TDX_MODULE_CALL does: TDCALL leaf ID, and the pointer to 'struct tdx_module_args'. Then 1) and 2) can be moved to the caller: - TDG.VP.VMCALL leaf ID can be passed via the function call argument; - 'struct tdx_module_args' is 'struct tdx_hypercall_args' + RCX, thus the bitmap of shared registers can be passed via RCX in the structure. Secondly, to move 3) and 4) out of assembly, make the TDX_HYPERCALL always save output registers to the structure. The caller then can: - Call __tdx_hypercall_failed() when TDX_HYPERCALL returns error; - Return R10 in the structure as the return code of the VMCALL leaf; With above changes, change the asm function from __tdx_hypercall() to __tdcall_hypercall(), and reimplement __tdx_hypercall() as the C wrapper of it. This avoids having to add another wrapper of __tdx_hypercall() (_tdx_hypercall() is already taken). The __tdcall_hypercall() will be replaced with a __tdcall() variant using TDX_MODULE_CALL in a later commit as the final goal is to have one assembly to handle both TDCALL and TDVMCALL. Currently, the __tdx_hypercall() asm is in '.noinstr.text'. To keep this unchanged, annotate __tdx_hypercall(), which is a C function now, as 'noinstr'. Remove the __tdx_hypercall_ret() as __tdx_hypercall() already does so. Implement __tdx_hypercall() in tdx-shared.c so it can be shared with the compressed code. Opportunistically fix a checkpatch error complaining using space around parenthesis '(' and ')' while moving the bitmap of shared registers to <asm/shared/tdx.h>. [ dhansen: quash new calls of __tdx_hypercall_ret() that showed up ] Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Kai Huang <kai.huang@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/all/0cbf25e7aee3256288045023a31f65f0cef90af4.1692096753.git.kai.huang%40intel.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 Restructured Text 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.