On Tue, Jun 27, 2023 at 02:12:50AM +1200, Kai Huang wrote: > On the platform with the "partial write machine check" erratum, a kernel > partial write to TDX private memory may cause unexpected machine check. > It would be nice if the #MC handler could print additional information > to show the #MC was TDX private memory error due to possible kernel bug. > > To do that, the machine check handler needs to use SEAMCALL to query > page type of the error memory from the TDX module, because there's no > existing infrastructure to track TDX private pages. > > SEAMCALL instruction causes #UD if CPU isn't in VMX operation. In #MC > handler, it is legal that CPU isn't in VMX operation when making this > SEAMCALL. Extend the TDX_MODULE_CALL macro to handle #UD so the > SEAMCALL can return error code instead of Oops in the #MC handler. > Opportunistically handles #GP too since they share the same code. > > A bonus is when kernel mistakenly calls SEAMCALL when CPU isn't in VMX > operation, or when TDX isn't enabled by the BIOS, or when the BIOS is > buggy, the kernel can get a nicer error message rather than a less > understandable Oops. > > Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> -- Kiryl Shutsemau / Kirill A. Shutemov
