On Wed, Jul 28 2021, Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx> wrote: > Improve make_secure_pte to avoid stalls when the system is heavily > overcommitted. This was especially problematic in kvm_s390_pv_unpack, > because of the loop over all pages that needed unpacking. > > Also fix kvm_s390_pv_init_vm to avoid stalls when the system is heavily > overcommitted. > > Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx> > --- > arch/s390/kernel/uv.c | 11 ++++++++--- > arch/s390/kvm/pv.c | 2 +- > 2 files changed, 9 insertions(+), 4 deletions(-) > > diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c > index aeb0a15bcbb7..fd0faa51c1bb 100644 > --- a/arch/s390/kernel/uv.c > +++ b/arch/s390/kernel/uv.c > @@ -196,11 +196,16 @@ static int make_secure_pte(pte_t *ptep, unsigned long addr, > if (!page_ref_freeze(page, expected)) > return -EBUSY; > set_bit(PG_arch_1, &page->flags); > - rc = uv_call(0, (u64)uvcb); > + rc = __uv_call(0, (u64)uvcb); > page_ref_unfreeze(page, expected); > - /* Return -ENXIO if the page was not mapped, -EINVAL otherwise */ > - if (rc) > + /* > + * Return -ENXIO if the page was not mapped, -EINVAL for other errors. > + * If busy or partially completed, return -EAGAIN. > + */ > + if (rc == 1) > rc = uvcb->rc == 0x10a ? -ENXIO : -EINVAL; > + else if (rc > 1) > + rc = -EAGAIN; > return rc; > } Possibly dumb question: when does the call return > 1? gmap_make_secure() will do a wait_on_page_writeback() for -EAGAIN, is that always the right thing to do?
