slbmfee/slbmfev instructions are very expensive, moreso than a regular
mfspr instruction, so minimising them significantly improves hash guest
exit performance. The slbmfev is only required if slbmfee found a valid
SLB entry.
Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
---
arch/powerpc/kvm/book3s_hv_p9_entry.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv_p9_entry.c b/arch/powerpc/kvm/book3s_hv_p9_entry.c
index 3fffcec67ff8..5e9e9f809297 100644
--- a/arch/powerpc/kvm/book3s_hv_p9_entry.c
+++ b/arch/powerpc/kvm/book3s_hv_p9_entry.c
@@ -459,10 +459,22 @@ static void __accumulate_time(struct kvm_vcpu *vcpu, struct kvmhv_tb_accumulator
#define accumulate_time(vcpu, next) do {} while (0)
#endif
-static inline void mfslb(unsigned int idx, u64 *slbee, u64 *slbev)
+static inline u64 mfslbv(unsigned int idx)
{
- asm volatile("slbmfev %0,%1" : "=r" (*slbev) : "r" (idx));
- asm volatile("slbmfee %0,%1" : "=r" (*slbee) : "r" (idx));
+ u64 slbev;
+
+ asm volatile("slbmfev %0,%1" : "=r" (slbev) : "r" (idx));
+
+ return slbev;
+}
+
+static inline u64 mfslbe(unsigned int idx)
+{
+ u64 slbee;
+
+ asm volatile("slbmfee %0,%1" : "=r" (slbee) : "r" (idx));
+
+ return slbee;
}
static inline void mtslb(u64 slbee, u64 slbev)
@@ -592,8 +604,10 @@ static void save_clear_guest_mmu(struct kvm *kvm, struct kvm_vcpu *vcpu)
*/
for (i = 0; i < vcpu->arch.slb_nr; i++) {
u64 slbee, slbev;
- mfslb(i, &slbee, &slbev);
+
+ slbee = mfslbe(i);
if (slbee & SLB_ESID_V) {
+ slbev = mfslbv(i);
vcpu->arch.slb[nr].orige = slbee | i;
vcpu->arch.slb[nr].origv = slbev;
nr++;
--
2.23.0
