| Subject | Re: [RFC v2 15/32] x86/tdx: Handle in-kernel MMIO | From | Dave Hansen <> | Date | Fri, 7 May 2021 14:52:21 -0700 |
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On 4/26/21 11:01 AM, Kuppuswamy Sathyanarayanan wrote: > Handle #VE due to MMIO operations. MMIO triggers #VE with EPT_VIOLATION > exit reason.
This needs a bit of a history lesson. "In traditional VMs, MMIO tends to be implemented by giving a guest access to an mapping which will cause a VMEXIT on access. That's not possible in a TDX guest..."
> For now we only handle subset of instruction that kernel uses for MMIO > oerations. User-space access triggers SIGBUS.
I still don't think that TDX guests should be doing things that they *KNOW* will cause #VE, including MMIO. I really want to hear a more discrete story about why this is the *best* way to do this for Linux instead of just a hack from the Windows binary driver ecosystem that seemed expedient.
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