Commit 241d1f19 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
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KVM: PPC: Book3S HV P9: Optimise hash guest SLB saving 



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: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211123095231.1036501-47-npiggin@gmail.com
parent b49c65c5

arch/powerpc/kvm/book3s_hv_p9_entry.c

+18 −4
Original line number Diff line number Diff line
@@ -487,10 +487,22 @@ 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)
@@ -620,8 +632,10 @@ 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++;