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SubjectRe: [PATCH 08/26] x86/tdx: Handle in-kernel MMIO
On Fri, Jan 07, 2022 at 08:49:26PM +0300, Kirill A. Shutemov wrote:
> To emulate an instruction the emulator needs two things:
> - R/W access to the register file to read/modify instruction arguments
> and see RIP of the faulted instruction.
> - Read access to memory where instruction is placed to see what to
> emualte. In this case it is guest kernel text.
> Both of them are not available to VMM in TDX environment:
> - Register file is never exposed to VMM. When a TD exits to the module,
> it saves registers into the state-save area allocated for that TD.
> The module then scrubs these registers before returning execution
> control to the VMM, to help prevent leakage of TD state.
> - Memory is encrypted TD-private key. The CPU disallows software other
> than the TDX module and TDs from making memory accesses using the
> private key.

Thanks, that's very helpful info. It would be nice to have it in the
commit message.


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