Re: [PATCH] x86/svm: retry after unhandled NPT fault if gfn was marked for recalculation

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 22/05/2020 14:04, Jan Beulich wrote:
> On 22.05.2020 13:11, Roger Pau Monné wrote:
>> That being said, I also don't like the fact that logdity is handled
>> differently between EPT and NPT, as on EPT it's handled as a
>> misconfig while on NPT it's handled as a violation.
> Because, well, there is no concept of misconfig in NPT.

Indeed.  Intel chose to split EPT errors into two - MISCONFIG for
structural errors (not present, or reserved bits set) and VIOLATION for
permissions errors.

AMD reused the same silicon pagewalker design, so have a single
NPT_FAULT vmexit which behaves much more like a regular pagefault,
encoding structural vs permission errors in the error code.

~Andrew