s390/kvm: support collaborative memory management
This patch enables Collaborative Memory Management (CMM) for kvm
on s390. CMM allows the guest to inform the host about page usage
(see arch/s390/mm/cmm.c). The host uses this information to avoid
swapping in unused pages in the page fault handler. Further, a CPU
provided list of unused invalid pages is processed to reclaim swap
space of not yet accessed unused pages.
[ Martin Schwidefsky: patch reordering and cleanup ]
Signed-off-by: Konstantin Weitz <konstantin.weitz@gmail.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 75beea6..aacb6b1 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -636,8 +636,49 @@
return 0;
}
+static int handle_essa(struct kvm_vcpu *vcpu)
+{
+ /* entries expected to be 1FF */
+ int entries = (vcpu->arch.sie_block->cbrlo & ~PAGE_MASK) >> 3;
+ unsigned long *cbrlo, cbrle;
+ struct gmap *gmap;
+ int i;
+
+ VCPU_EVENT(vcpu, 5, "cmma release %d pages", entries);
+ gmap = vcpu->arch.gmap;
+ vcpu->stat.instruction_essa++;
+ if (!kvm_enabled_cmma() || !vcpu->arch.sie_block->cbrlo)
+ return kvm_s390_inject_program_int(vcpu, PGM_OPERATION);
+
+ if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
+ return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
+
+ if (((vcpu->arch.sie_block->ipb & 0xf0000000) >> 28) > 6)
+ return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
+
+ /* Rewind PSW to repeat the ESSA instruction */
+ vcpu->arch.sie_block->gpsw.addr =
+ __rewind_psw(vcpu->arch.sie_block->gpsw, 4);
+ vcpu->arch.sie_block->cbrlo &= PAGE_MASK; /* reset nceo */
+ cbrlo = phys_to_virt(vcpu->arch.sie_block->cbrlo);
+ down_read(&gmap->mm->mmap_sem);
+ for (i = 0; i < entries; ++i) {
+ cbrle = cbrlo[i];
+ if (unlikely(cbrle & ~PAGE_MASK || cbrle < 2 * PAGE_SIZE))
+ /* invalid entry */
+ break;
+ /* try to free backing */
+ __gmap_zap(cbrle, gmap);
+ }
+ up_read(&gmap->mm->mmap_sem);
+ if (i < entries)
+ return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
+ return 0;
+}
+
static const intercept_handler_t b9_handlers[256] = {
[0x8d] = handle_epsw,
+ [0xab] = handle_essa,
[0xaf] = handle_pfmf,
};