> On 11/30/22 00:34, Huang, Kai wrote: > > On Wed, 2022-11-30 at 11:35 +0800, Binbin Wu wrote: > >> On 11/21/2022 8:26 AM, Kai Huang wrote: > >>> After the array of TDMRs and the global KeyID are configured to the > >>> TDX module, use TDH.SYS.KEY.CONFIG to configure the key of the > >>> global KeyID on all packages. > >>> > >>> TDH.SYS.KEY.CONFIG must be done on one (any) cpu for each package. > >>> And it cannot run concurrently on different CPUs. Implement a > >>> helper to run SEAMCALL on one cpu for each package one by one, and > >>> use it to configure the global KeyID on all packages. > >>> > >>> Intel hardware doesn't guarantee cache coherency across different > >>> KeyIDs. The kernel needs to flush PAMT's dirty cachelines > >>> (associated with KeyID 0) before the TDX module uses the global > >>> KeyID to access the PAMT. Following the TDX module specification, > >>> flush cache before configuring the global KeyID on all packages. > >>> > >>> Given the PAMT size can be large (~1/256th of system RAM), just use > >>> WBINVD on all CPUs to flush. > >>> > >>> Note if any TDH.SYS.KEY.CONFIG fails, the TDX module may already > >>> have used the global KeyID to write any PAMT. Therefore, need to > >>> use WBINVD to flush cache before freeing the PAMTs back to the > >>> kernel. Note using MOVDIR64B (which changes the page's associated > >>> KeyID from the old TDX private KeyID back to KeyID 0, which is used > >>> by the kernel) > >> > >> It seems not accurate to say MOVDIR64B changes the page's associated > KeyID. > >> It just uses the current KeyID for memory operations. > > > > The "write" to the memory changes the page's associated KeyID to the > > KeyID that does the "write". A more accurate expression perhaps > > should be MOVDIR64B + MFENSE, but I think it doesn't matter in changelog. > > Just delete it from the changelog. It's a distraction. I'm not even sure it's > *necessary* to do any memory content conversion after the TDX module has > written gunk. > > There won't be any integrity issues because integrity errors don't do anything for > KeyID-0 (no #MC). > > I _think_ the reads of the page using KeyID-0 will see abort page semantics. > That's *FINE*. I'll remove this from the changelog. Thanks!
