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

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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: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211123095231.1036501-27-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2021-11-23 19:52:04 +10:00 committed by Michael Ellerman
parent 9a1e530bbb
commit 9dfe7aa7bc
1 changed files with 31 additions and 20 deletions
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51
arch/powerpc/kvm/book3s_hv.c
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@ -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);
mtspr(SPRN_AMR, vcpu->arch.amr);
mtspr(SPRN_UAMOR, vcpu->arch.uamor);
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);
mtspr(SPRN_IAMR, host_os_sprs->iamr);
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()) {
/*