On 7/28/21 4:26 PM, Claudio Imbrenda 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. Fixes tag? > > 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); We should exchange rc with cc since that's what we get back from __uv_call(). Technically we always get a cc but for the other functions it's only ever 0/1 which translates to success/error so rc is ok. > 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; Could you define the CCs in uv.h and check against the constants here so it's easier to understand that the rc > 1 checks against a "UV was busy please re-issue the call again" cc? Maybe also make it explicit for cc 2 and 3 instead of cc > 1 > } > > diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c > index c8841f476e91..e007df11a2fe 100644 > --- a/arch/s390/kvm/pv.c > +++ b/arch/s390/kvm/pv.c > @@ -196,7 +196,7 @@ int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc) > uvcb.conf_base_stor_origin = (u64)kvm->arch.pv.stor_base; > uvcb.conf_virt_stor_origin = (u64)kvm->arch.pv.stor_var; > > - cc = uv_call(0, (u64)&uvcb); > + cc = uv_call_sched(0, (u64)&uvcb); > *rc = uvcb.header.rc; > *rrc = uvcb.header.rrc; > KVM_UV_EVENT(kvm, 3, "PROTVIRT CREATE VM: handle %llx len %llx rc %x rrc %x", >
