Hi Maxim, On 11/14/2022 8:01 PM, Maxim Levitsky wrote: > On Mon, 2022-11-14 at 13:32 +0530, Santosh Shukla wrote: >> >> >> On 10/27/2022 2:08 PM, Santosh Shukla wrote: >>> VNMI Spec is at [1]. >>> >>> Change History: >>> >>> v5 (6.1-rc2) >>> 01,02,06 - Renamed s/X86_FEATURE_V_NMI/X86_FEATURE_AMD_VNMI (Jim Mattson) >>> >> >> Gentle reminder. >> >> Thanks, >> Santosh >> > > I started reviewing it today and I think there are still few issues, > and the biggest one is that if a NMI arrives while vNMI injection > is pending, current code just drops such NMI. > > We had a discussion about this, like forcing immeditate vm exit I believe, We discussed above case in [1] i.e.. HW can handle the second (/pending)virtual NMI while the guest processing first virtual NMI w/o vmexit. is it same scenario or different one that you are mentioning? [1] https://lore.kernel.org/lkml/1782cdbb-8274-8c3d-fa98-29147f1e5d1e@xxxxxxx/ Thanks, Santosh > in this case and such but I have a simplier idea: > > In this case we can just open the NMI window in the good old way > by intercepting IRET, STGI, and or RSM (which is intercepted anyway), > > and only if we already *just* intercepted IRET, only then just drop > the new NMI instead of single stepping over it based on reasoning that > its 3rd NMI (one is almost done the servicing (its IRET is executing), > one is pending injection, and we want to inject another one. > > Does this sound good to you? It won't work for SEV-ES as it looks > like it doesn't intercept IRET, but it might be a reasonable tradeof > for SEV-ES guests to accept that we can't inject a NMI if one is > already pending injection. > > Best regards, > Maxim Levitsky >
