From d724c9e54939a597592de3659541da11fc7aa112 Mon Sep 17 00:00:00 2001 From: Suraj Jitindar Singh Date: Thu, 30 May 2019 12:17:18 +1000 Subject: [PATCH] KVM: PPC: Book3S HV: Restore SPRG3 in kvmhv_p9_guest_entry() The sprgs are a set of 4 general purpose sprs provided for software use. SPRG3 is special in that it can also be read from userspace. Thus it is used on linux to store the cpu and numa id of the process to speed up syscall access to this information. This register is overwritten with the guest value on kvm guest entry, and so needs to be restored on exit again. Thus restore the value on the guest exit path in kvmhv_p9_guest_entry(). Cc: stable@vger.kernel.org # v4.20+ 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 --- arch/powerpc/kvm/book3s_hv.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 9f49339c6d50..5e840113eda4 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3662,6 +3662,7 @@ int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, vc->in_guest = 0; mtspr(SPRN_DEC, local_paca->kvm_hstate.dec_expires - mftb()); + mtspr(SPRN_SPRG_VDSO_WRITE, local_paca->sprg_vdso); kvmhv_load_host_pmu(); -- 2.30.2