On 12/6/22 12:13 PM, Michael Kelley (LINUX) wrote: > From: Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> >> >> >> >> On 12/1/22 7:30 PM, Michael Kelley wrote: >>> Full Hyper-V initialization, including support for hypercalls, is done >>> as an apic_post_init callback via late_time_init(). mem_encrypt_init() >>> needs to make hypercalls when it marks swiotlb memory as decrypted. >>> But mem_encrypt_init() is currently called a few lines before >>> late_time_init(), so the hypercalls don't work. >> >> Did you consider moving hyper-v hypercall initialization before >> mem_encrypt_init(). Is there any dependency issue? > > Hyper-V initialization has historically been done using the callbacks > that exist in the x86 initialization paths, rather than adding explicit > Hyper-V init calls. As noted above, the full Hyper-V init is done on > the apic_post_init callback via late_time_init(). Conceivably we could > add an explicit call to do the Hyper-V init, but I think there's still a > problem in putting that Hyper-V init prior to the current location of > mem_encrypt_init(). I'd have to go check the history, but I think the > Hyper-V init needs to happen after the APIC is initialized. Ok. If there is a dependency or complexity issue, I recommend adding that detail in the commit log. > > It seems like moving mem_encrypt_init() slightly later is the cleaner > long-term solution. Are you aware of a likely problem arising in the > future with moving mem_encrypt_init()? I did not investigate in depth, but there appears to be no problem with moving mem_encrypt_init(). But my point is, if it is possible to fix this easily by changing Hyper-v specific initialization, we should consider it first before considering moving the common mem_encrypt_init() function. > > Michael > >> >>> >>> Fix this by moving mem_encrypt_init() after late_time_init() and >>> related clock initializations. The intervening initializations don't >>> do any I/O that requires the swiotlb, so moving mem_encrypt_init() >>> slightly later has no impact. >>> -- Sathyanarayanan Kuppuswamy Linux Kernel Developer
