Re: [PATCH v1 7/9] memory: introduce RAM_NORESERVE and wire it up in qemu_ram_mmap()

[Cornelia Huck]

On Tue, 2 Mar 2021 20:02:34 +0100
David Hildenbrand <david@redhat.com> wrote:

> On 02.03.21 18:32, Peter Xu wrote:
> > On Tue, Feb 09, 2021 at 02:49:37PM +0100, David Hildenbrand wrote:  
> >> @@ -899,13 +899,17 @@ int kvm_s390_mem_op_pv(S390CPU *cpu, uint64_t 
> >> offset, void *hostbuf,
> >>    * to grow. We also have to use MAP parameters that avoid
> >>    * read-only mapping of guest pages.
> >>    */
> >> -static void *legacy_s390_alloc(size_t size, uint64_t *align, bool shared)
> >> +static void *legacy_s390_alloc(size_t size, uint64_t *align, bool shared,
> >> +                               bool noreserve)
> >>   {
> >>       static void *mem;
> >>   
> >>       if (mem) {
> >>           /* we only support one allocation, which is enough for initial 
> >> ram */
> >>           return NULL;
> >> +    } else if (noreserve) {
> >> +        error_report("Skipping reservation of swap space is not 
> >> supported.");
> >> +        return NULL  
> > 
> > Semicolon missing.  
> 
> Thanks for catching that!

Regardless of that (and this patch set), can we finally get rid of
legacy_s390_alloc? We already fence off running with a kernel prior to
3.15, and KVM_CAP_S390_COW depends on ESOP -- are non-ESOP kvm hosts
still relevant? This seems to be a generation 10 feature; do we
realistically expect anyone running this on e.g. a z/VM host that
doesn't provide ESOP?