On Mon, Feb 26, 2024, Isaku Yamahata wrote:
> On Thu, Feb 01, 2024 at 03:06:46PM -0800,
> David Matlack <dmatlack@xxxxxxxxxx> wrote:
>
> > +Vipin Sharma
> >
> > On Wed, Jan 31, 2024 at 4:21 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote:
> > > On Mon, Jan 22, 2024, isaku.yamahata@xxxxxxxxx wrote:
> > >
> > > The real reason for this drive-by pseudo-review is that I am hoping/wishing we
> > > can turn this into a generic KVM ioctl() to allow userspace to pre-map guest
> > > memory[*].
> > >
> > > If we're going to carry non-trivial code, we might as well squeeze as much use
> > > out of it as we can.
> > >
> > > Beyond wanting to shove this into KVM_MEMORY_ENCRYPT_OP, is there any reason why
> > > this is a VM ioctl() and not a vCPU ioctl()? Very roughly, couldn't we use a
> > > struct like this as input to a vCPU ioctl() that maps memory, and optionally
> > > initializes memory from @source?
> > >
> > > struct kvm_memory_mapping {
> > > __u64 base_gfn;
> > > __u64 nr_pages;
> > > __u64 flags;
> > > __u64 source;
> > > }
> > >
> > > TDX would need to do special things for copying the source, but beyond that most
> > > of the code in this function is generic.
> > >
> > > [*] https://lore.kernel.org/all/65262e67-7885-971a-896d-ad9c0a760907@xxxxxxxxx
> >
> > We would also be interested in such an API to reduce the guest
> > performance impact of intra-host migration.
>
> I introduce KVM_MEMORY_MAPPING and KVM_CAP_MEMORY_MAPPING with v19.
KVM_MEMORY_MAPPING is not a good ioctl() name. There needs to be a verb in there
somewhere, e.g. KVM_MAP_MEMORY, KVM_FAULTIN_MEMORY, etc.
> We can continue the discussion there.
No, we absolutely cannot continue the conversation there. That is not how kernel
development works.
Enough is enough. I am archiving v19 and not touching it.
Please post an RFC for _just_ this functionality, and follow-up in existing,
pre-v19 conversations for anything else that changed between v18 and v19 and might
need additional input/discussion.
