> -----Original Message----- > From: Huang, Kai <[email protected]> > Sent: Thursday, July 24, 2025 2:13 PM > To: Reshetova, Elena <[email protected]>; Hansen, Dave > <[email protected]> > Cc: [email protected]; [email protected]; Scarlata, Vincent R > <[email protected]>; [email protected]; [email protected]; > Annapurve, Vishal <[email protected]>; [email protected]; > Mallick, Asit K <[email protected]>; Aktas, Erdem > <[email protected]>; Cai, Chong <[email protected]>; Bondarevska, > Nataliia <[email protected]>; [email protected]; Raynor, Scott > <[email protected]> > Subject: Re: [PATCH v9 6/6] x86/sgx: Enable automatic SVN updates for SGX > enclaves > > On Thu, 2025-07-24 at 11:02 +0300, Reshetova, Elena wrote: > > == Background == > > > > ENCLS[EUPDATESVN] is a new SGX instruction [1] which allows enclave > > attestation to include information about updated microcode SVN without a > > reboot. Before an EUPDATESVN operation can be successful, all SGX memory > > (aka. EPC) must be marked as “unused” in the SGX hardware metadata > > (aka.EPCM). This requirement ensures that no compromised enclave can > > survive the EUPDATESVN procedure and provides an opportunity to generate > > new cryptographic assets. > > > > == Patch Contents == > > Nit: you can use "Solution" instead of "Patch Contents".
Sure. > > > > > Attempt to execute ENCLS[EUPDATESVN] every time the first file descriptor > > is obtained via sgx_(vepc_)open(). In the most common case the microcode > > SVN is already up-to-date, and the operation succeeds without updating SVN. > > (Sorry I forgot to say this in the previous versions): > > If I read the pseudo code correctly, when the SVN is already up-to-date, > the EUPDATESVN doesn't update SVN but it re-generates crypto assets > anyway. > > This is no harm per the pseudo code, since the "crypto assets" is actually > the CR_BASE_KEY which is only used by EWB/ELDU flow per the SDM. > > In other words, it doesn't impact other enclave visible keys (those from > EGETKEY) such as sealing key. > > I think this is important. Because if enclave visible keys such as > sealing key are lost on EUPDATESVN when SVN is already up-to-date (which > is the most common case), it will bring significant visible impact to > enclave. E.g., one enclave could find its secret encrypted by sealing key > could never be retrieved after it restarts. > > Assuming I didn't miss anything, can we also mention this in the > changelog? Yes, you are right, anything like above behaviour would be a nightmare in practice. So would smth like this work as an additional text: "Note that in cases when SVN is already up-to-date and EUPDATESVN is executed, it does not affect enclaves' visible keys obtained via EGETKEY instruction." ? Best Regards, Elena.
