Commit 9dfe7aa7 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

KVM: PPC: Book3S HV P9: Only execute mtSPR if the value changed 



Keep better track of the current SPR value in places where
they are to be loaded with a new context, to reduce expensive
mtSPR operations.

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/20211123095231.1036501-27-npiggin@gmail.com
parent 9a1e530b

arch/powerpc/kvm/book3s_hv.c

+31 −20
Original line number Diff line number Diff line
@@ -4055,20 +4055,28 @@ static void switch_pmu_to_host(struct kvm_vcpu *vcpu, 
	}

}



static void load_spr_state(struct kvm_vcpu *vcpu)

static void load_spr_state(struct kvm_vcpu *vcpu,

				struct p9_host_os_sprs *host_os_sprs)

{

	mtspr(SPRN_DSCR, vcpu->arch.dscr);

	mtspr(SPRN_IAMR, vcpu->arch.iamr);

	mtspr(SPRN_PSPB, vcpu->arch.pspb);

	mtspr(SPRN_FSCR, vcpu->arch.fscr);

	mtspr(SPRN_TAR, vcpu->arch.tar);

	mtspr(SPRN_EBBHR, vcpu->arch.ebbhr);

	mtspr(SPRN_EBBRR, vcpu->arch.ebbrr);

	mtspr(SPRN_BESCR, vcpu->arch.bescr);



	if (cpu_has_feature(CPU_FTR_P9_TIDR))

		mtspr(SPRN_TIDR, vcpu->arch.tid);

	if (host_os_sprs->iamr != vcpu->arch.iamr)

		mtspr(SPRN_IAMR, vcpu->arch.iamr);

	if (host_os_sprs->amr != vcpu->arch.amr)

		mtspr(SPRN_AMR, vcpu->arch.amr);

	if (vcpu->arch.uamor != 0)

		mtspr(SPRN_UAMOR, vcpu->arch.uamor);

	if (host_os_sprs->fscr != vcpu->arch.fscr)

		mtspr(SPRN_FSCR, vcpu->arch.fscr);

	if (host_os_sprs->dscr != vcpu->arch.dscr)

		mtspr(SPRN_DSCR, vcpu->arch.dscr);

	if (vcpu->arch.pspb != 0)

		mtspr(SPRN_PSPB, vcpu->arch.pspb);



	/*

	 * DAR, DSISR, and for nested HV, SPRGs must be set with MSR[RI]
@@ -4083,20 +4091,21 @@ static void load_spr_state(struct kvm_vcpu *vcpu) 


static void store_spr_state(struct kvm_vcpu *vcpu)

{

	vcpu->arch.ctrl = mfspr(SPRN_CTRLF);



	vcpu->arch.iamr = mfspr(SPRN_IAMR);

	vcpu->arch.pspb = mfspr(SPRN_PSPB);

	vcpu->arch.fscr = mfspr(SPRN_FSCR);

	vcpu->arch.tar = mfspr(SPRN_TAR);

	vcpu->arch.ebbhr = mfspr(SPRN_EBBHR);

	vcpu->arch.ebbrr = mfspr(SPRN_EBBRR);

	vcpu->arch.bescr = mfspr(SPRN_BESCR);



	if (cpu_has_feature(CPU_FTR_P9_TIDR))

		vcpu->arch.tid = mfspr(SPRN_TIDR);

	vcpu->arch.iamr = mfspr(SPRN_IAMR);

	vcpu->arch.amr = mfspr(SPRN_AMR);

	vcpu->arch.uamor = mfspr(SPRN_UAMOR);

	vcpu->arch.fscr = mfspr(SPRN_FSCR);

	vcpu->arch.dscr = mfspr(SPRN_DSCR);

	vcpu->arch.pspb = mfspr(SPRN_PSPB);



	vcpu->arch.ctrl = mfspr(SPRN_CTRLF);

}



static void save_p9_host_os_sprs(struct p9_host_os_sprs *host_os_sprs)
@@ -4107,6 +4116,7 @@ static void save_p9_host_os_sprs(struct p9_host_os_sprs *host_os_sprs) 
	host_os_sprs->iamr = mfspr(SPRN_IAMR);

	host_os_sprs->amr = mfspr(SPRN_AMR);

	host_os_sprs->fscr = mfspr(SPRN_FSCR);

	host_os_sprs->dscr = mfspr(SPRN_DSCR);

}



/* vcpu guest regs must already be saved */
@@ -4115,19 +4125,20 @@ static void restore_p9_host_os_sprs(struct kvm_vcpu *vcpu, 
{

	mtspr(SPRN_SPRG_VDSO_WRITE, local_paca->sprg_vdso);



	mtspr(SPRN_PSPB, 0);

	mtspr(SPRN_UAMOR, 0);



	mtspr(SPRN_DSCR, host_os_sprs->dscr);

	if (cpu_has_feature(CPU_FTR_P9_TIDR))

		mtspr(SPRN_TIDR, host_os_sprs->tidr);

	if (host_os_sprs->iamr != vcpu->arch.iamr)

		mtspr(SPRN_IAMR, host_os_sprs->iamr);



	if (vcpu->arch.uamor != 0)

		mtspr(SPRN_UAMOR, 0);

	if (host_os_sprs->amr != vcpu->arch.amr)

		mtspr(SPRN_AMR, host_os_sprs->amr);



	if (host_os_sprs->fscr != vcpu->arch.fscr)

		mtspr(SPRN_FSCR, host_os_sprs->fscr);

	if (host_os_sprs->dscr != vcpu->arch.dscr)

		mtspr(SPRN_DSCR, host_os_sprs->dscr);

	if (vcpu->arch.pspb != 0)

		mtspr(SPRN_PSPB, 0);



	/* Save guest CTRL register, set runlatch to 1 */

	if (!(vcpu->arch.ctrl & 1))
@@ -4219,7 +4230,7 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, 
#endif

	mtspr(SPRN_VRSAVE, vcpu->arch.vrsave);



	load_spr_state(vcpu);

	load_spr_state(vcpu, &host_os_sprs);



	if (kvmhv_on_pseries()) {

		/*