Re: [PATCH 08/10] KVM: SEV: define VM types for SEV and SEV-ES

[Paolo Bonzini]

On 2/15/24 02:19, Michael Roth wrote:
> >   #define KVM_X86_DEFAULT_VM	0
> >   #define KVM_X86_SW_PROTECTED_VM	(KVM_X86_DEFAULT_VM | __KVM_X86_PRIVATE_MEM_TYPE)
> > +#define KVM_X86_SEV_VM		8
> Hmm... would it make sense to decouple the VM types and their associated
> capabilities? Only bit 2 is left in the lower range after this, and using any
> bits beyond TDX's bit 4 risks overflowing check_extension ioctl's 32-bit return
> value.

Yes, the idea was to leave 0..7 for vendor independent types (with 0 and 
1 in use), 8..15 for AMD (3 of them being reserved already for 
SEV/SEV-ES/SEV-SNP), 16..23 for Intel.

> Maybe a separate lookup table instead?

The mask was nice because it can be used in relatively hot paths... 
I'll keep them but move the constants away from uapi/ headers.

Paolo