KVM: s390: CMMA tracking, ESSA emulation, migration mode
* Add a migration state bitmap to keep track of which pages have dirty
CMMA information.
* Disable CMMA by default, so we can track if it's used or not. Enable
it on first use like we do for storage keys (unless we are doing a
migration).
* Creates a VM attribute to enter and leave migration mode.
* In migration mode, CMMA is disabled in the SIE block, so ESSA is
always interpreted and emulated in software.
* Free the migration state on VM destroy.
Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index c03106c..a226c45 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -24,6 +24,7 @@
#include <asm/ebcdic.h>
#include <asm/sysinfo.h>
#include <asm/pgtable.h>
+#include <asm/page-states.h>
#include <asm/pgalloc.h>
#include <asm/gmap.h>
#include <asm/io.h>
@@ -949,13 +950,72 @@ static int handle_pfmf(struct kvm_vcpu *vcpu)
return 0;
}
+static inline int do_essa(struct kvm_vcpu *vcpu, const int orc)
+{
+ struct kvm_s390_migration_state *ms = vcpu->kvm->arch.migration_state;
+ int r1, r2, nappended, entries;
+ unsigned long gfn, hva, res, pgstev, ptev;
+ unsigned long *cbrlo;
+
+ /*
+ * We don't need to set SD.FPF.SK to 1 here, because if we have a
+ * machine check here we either handle it or crash
+ */
+
+ kvm_s390_get_regs_rre(vcpu, &r1, &r2);
+ gfn = vcpu->run->s.regs.gprs[r2] >> PAGE_SHIFT;
+ hva = gfn_to_hva(vcpu->kvm, gfn);
+ entries = (vcpu->arch.sie_block->cbrlo & ~PAGE_MASK) >> 3;
+
+ if (kvm_is_error_hva(hva))
+ return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
+
+ nappended = pgste_perform_essa(vcpu->kvm->mm, hva, orc, &ptev, &pgstev);
+ if (nappended < 0) {
+ res = orc ? 0x10 : 0;
+ vcpu->run->s.regs.gprs[r1] = res; /* Exception Indication */
+ return 0;
+ }
+ res = (pgstev & _PGSTE_GPS_USAGE_MASK) >> 22;
+ /*
+ * Set the block-content state part of the result. 0 means resident, so
+ * nothing to do if the page is valid. 2 is for preserved pages
+ * (non-present and non-zero), and 3 for zero pages (non-present and
+ * zero).
+ */
+ if (ptev & _PAGE_INVALID) {
+ res |= 2;
+ if (pgstev & _PGSTE_GPS_ZERO)
+ res |= 1;
+ }
+ vcpu->run->s.regs.gprs[r1] = res;
+ /*
+ * It is possible that all the normal 511 slots were full, in which case
+ * we will now write in the 512th slot, which is reserved for host use.
+ * In both cases we let the normal essa handling code process all the
+ * slots, including the reserved one, if needed.
+ */
+ if (nappended > 0) {
+ cbrlo = phys_to_virt(vcpu->arch.sie_block->cbrlo & PAGE_MASK);
+ cbrlo[entries] = gfn << PAGE_SHIFT;
+ }
+
+ if (orc) {
+ /* increment only if we are really flipping the bit to 1 */
+ if (!test_and_set_bit(gfn, ms->pgste_bitmap))
+ atomic64_inc(&ms->dirty_pages);
+ }
+
+ return nappended;
+}
+
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;
struct gmap *gmap;
- int i;
+ int i, orc;
VCPU_EVENT(vcpu, 4, "ESSA: release %d pages", entries);
gmap = vcpu->arch.gmap;
@@ -965,12 +1025,45 @@ static int handle_essa(struct kvm_vcpu *vcpu)
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)
+ /* Check for invalid operation request code */
+ orc = (vcpu->arch.sie_block->ipb & 0xf0000000) >> 28;
+ if (orc > ESSA_MAX)
return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
- /* Retry the ESSA instruction */
- kvm_s390_retry_instr(vcpu);
+ if (likely(!vcpu->kvm->arch.migration_state)) {
+ /*
+ * CMMA is enabled in the KVM settings, but is disabled in
+ * the SIE block and in the mm_context, and we are not doing
+ * a migration. Enable CMMA in the mm_context.
+ * Since we need to take a write lock to write to the context
+ * to avoid races with storage keys handling, we check if the
+ * value really needs to be written to; if the value is
+ * already correct, we do nothing and avoid the lock.
+ */
+ if (vcpu->kvm->mm->context.use_cmma == 0) {
+ down_write(&vcpu->kvm->mm->mmap_sem);
+ vcpu->kvm->mm->context.use_cmma = 1;
+ up_write(&vcpu->kvm->mm->mmap_sem);
+ }
+ /*
+ * If we are here, we are supposed to have CMMA enabled in
+ * the SIE block. Enabling CMMA works on a per-CPU basis,
+ * while the context use_cmma flag is per process.
+ * It's possible that the context flag is enabled and the
+ * SIE flag is not, so we set the flag always; if it was
+ * already set, nothing changes, otherwise we enable it
+ * on this CPU too.
+ */
+ vcpu->arch.sie_block->ecb2 |= ECB2_CMMA;
+ /* Retry the ESSA instruction */
+ kvm_s390_retry_instr(vcpu);
+ } else {
+ /* Account for the possible extra cbrl entry */
+ i = do_essa(vcpu, orc);
+ if (i < 0)
+ return i;
+ entries += i;
+ }
vcpu->arch.sie_block->cbrlo &= PAGE_MASK; /* reset nceo */
cbrlo = phys_to_virt(vcpu->arch.sie_block->cbrlo);
down_read(&gmap->mm->mmap_sem);