From: Suraj Jitindar Singh Date: Tue, 30 Apr 2019 00:41:23 +0000 (+1000) Subject: KVM: PPC: Book3S HV: Save/restore vrsave register in kvmhv_p9_guest_entry() X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=44b198aee1f2649534bdf08bfd7517c56da2ed7e;p=openwrt%2Fstaging%2Fblogic.git KVM: PPC: Book3S HV: Save/restore vrsave register in kvmhv_p9_guest_entry() On POWER9 and later processors where the host can schedule vcpus on a per thread basis, there is a streamlined entry path used when the guest is radix. This entry path saves/restores the fp and vr state in kvmhv_p9_guest_entry() by calling store_[fp/vr]_state() and load_[fp/vr]_state(). This is the same as the old entry path however the old entry path also saved/restored the VRSAVE register, which isn't done in the new entry path. This means that the vrsave register is now volatile across guest exit, which is an incorrect change in behaviour. Fix this by saving/restoring the vrsave register in kvmhv_p9_guest_entry(). This restores the old, correct, behaviour. Fixes: 95a6432ce9038 ("KVM: PPC: Book3S HV: Streamlined guest entry/exit path on P9 for radix guests") Signed-off-by: Suraj Jitindar Singh Signed-off-by: Paul Mackerras --- diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index d250a76b1153..e4c5a4c79629 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3549,6 +3549,7 @@ int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, #ifdef CONFIG_ALTIVEC load_vr_state(&vcpu->arch.vr); #endif + mtspr(SPRN_VRSAVE, vcpu->arch.vrsave); mtspr(SPRN_DSCR, vcpu->arch.dscr); mtspr(SPRN_IAMR, vcpu->arch.iamr); @@ -3640,6 +3641,7 @@ int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, #ifdef CONFIG_ALTIVEC store_vr_state(&vcpu->arch.vr); #endif + vcpu->arch.vrsave = mfspr(SPRN_VRSAVE); if (cpu_has_feature(CPU_FTR_TM) || cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST))