From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Gibson Subject: Re: [PATCH v4 25/32] KVM: PPC: Book3S HV: Invalidate TLB when nested vcpu moves physical cpu Date: Fri, 5 Oct 2018 14:09:08 +1000 Message-ID: <20181005040908.GK7004@umbus.fritz.box> References: <1538654169-15602-1-git-send-email-paulus@ozlabs.org> <1538654169-15602-26-git-send-email-paulus@ozlabs.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="sdEQJo40s7ofW8iR" Cc: linuxppc-dev@ozlabs.org, kvm-ppc@vger.kernel.org, kvm@vger.kernel.org To: Paul Mackerras Return-path: Content-Disposition: inline In-Reply-To: <1538654169-15602-26-git-send-email-paulus@ozlabs.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org Sender: "Linuxppc-dev" List-Id: kvm.vger.kernel.org --sdEQJo40s7ofW8iR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Oct 04, 2018 at 09:56:02PM +1000, Paul Mackerras wrote: > From: Suraj Jitindar Singh >=20 > This is only done at level 0, since only level 0 knows which physical > CPU a vcpu is running on. This does for nested guests what L0 already > did for its own guests, which is to flush the TLB on a pCPU when it > goes to run a vCPU there, and there is another vCPU in the same VM > which previously ran on this pCPU and has now started to run on another > pCPU. This is to handle the situation where the other vCPU touched > a mapping, moved to another pCPU and did a tlbiel (local-only tlbie) > on that new pCPU and thus left behind a stale TLB entry on this pCPU. >=20 > This introduces a limit on the the vcpu_token values used in the > H_ENTER_NESTED hcall -- they must now be less than NR_CPUS. This does make the vcpu tokens no longer entirely opaque to the L0. It works for now, because the only L1 is Linux and we know basically how it allocates those tokens. Eventually we probably want some way to either remove this restriction or to advertise the limit to the L1. > [paulus@ozlabs.org - made prev_cpu array be unsigned short[] to reduce > memory consumption.] >=20 > Signed-off-by: Suraj Jitindar Singh > Signed-off-by: Paul Mackerras Reviewed-by: David Gibson > --- > arch/powerpc/include/asm/kvm_book3s_64.h | 3 + > arch/powerpc/kvm/book3s_hv.c | 101 +++++++++++++++++++------= ------ > arch/powerpc/kvm/book3s_hv_nested.c | 5 ++ > 3 files changed, 71 insertions(+), 38 deletions(-) >=20 > diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/incl= ude/asm/kvm_book3s_64.h > index aa5bf85..1e96027 100644 > --- a/arch/powerpc/include/asm/kvm_book3s_64.h > +++ b/arch/powerpc/include/asm/kvm_book3s_64.h > @@ -52,6 +52,9 @@ struct kvm_nested_guest { > long refcnt; /* number of pointers to this struct */ > struct mutex tlb_lock; /* serialize page faults and tlbies */ > struct kvm_nested_guest *next; > + cpumask_t need_tlb_flush; > + cpumask_t cpu_in_guest; > + unsigned short prev_cpu[NR_CPUS]; > }; > =20 > /* > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index ba58883..53a967ea 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -2397,10 +2397,18 @@ static void kvmppc_release_hwthread(int cpu) > =20 > static void radix_flush_cpu(struct kvm *kvm, int cpu, struct kvm_vcpu *v= cpu) > { > + struct kvm_nested_guest *nested =3D vcpu->arch.nested; > + cpumask_t *cpu_in_guest; > int i; > =20 > cpu =3D cpu_first_thread_sibling(cpu); > - cpumask_set_cpu(cpu, &kvm->arch.need_tlb_flush); > + if (nested) { > + cpumask_set_cpu(cpu, &nested->need_tlb_flush); > + cpu_in_guest =3D &nested->cpu_in_guest; > + } else { > + cpumask_set_cpu(cpu, &kvm->arch.need_tlb_flush); > + cpu_in_guest =3D &kvm->arch.cpu_in_guest; > + } > /* > * Make sure setting of bit in need_tlb_flush precedes > * testing of cpu_in_guest bits. The matching barrier on > @@ -2408,13 +2416,23 @@ static void radix_flush_cpu(struct kvm *kvm, int = cpu, struct kvm_vcpu *vcpu) > */ > smp_mb(); > for (i =3D 0; i < threads_per_core; ++i) > - if (cpumask_test_cpu(cpu + i, &kvm->arch.cpu_in_guest)) > + if (cpumask_test_cpu(cpu + i, cpu_in_guest)) > smp_call_function_single(cpu + i, do_nothing, NULL, 1); > } > =20 > static void kvmppc_prepare_radix_vcpu(struct kvm_vcpu *vcpu, int pcpu) > { > + struct kvm_nested_guest *nested =3D vcpu->arch.nested; > struct kvm *kvm =3D vcpu->kvm; > + int prev_cpu; > + > + if (!cpu_has_feature(CPU_FTR_HVMODE)) > + return; > + > + if (nested) > + prev_cpu =3D nested->prev_cpu[vcpu->arch.nested_vcpu_id]; > + else > + prev_cpu =3D vcpu->arch.prev_cpu; > =20 > /* > * With radix, the guest can do TLB invalidations itself, > @@ -2428,12 +2446,46 @@ static void kvmppc_prepare_radix_vcpu(struct kvm_= vcpu *vcpu, int pcpu) > * ran to flush the TLB. The TLB is shared between threads, > * so we use a single bit in .need_tlb_flush for all 4 threads. > */ > - if (vcpu->arch.prev_cpu !=3D pcpu) { > - if (vcpu->arch.prev_cpu >=3D 0 && > - cpu_first_thread_sibling(vcpu->arch.prev_cpu) !=3D > + if (prev_cpu !=3D pcpu) { > + if (prev_cpu >=3D 0 && > + cpu_first_thread_sibling(prev_cpu) !=3D > cpu_first_thread_sibling(pcpu)) > - radix_flush_cpu(kvm, vcpu->arch.prev_cpu, vcpu); > - vcpu->arch.prev_cpu =3D pcpu; > + radix_flush_cpu(kvm, prev_cpu, vcpu); > + if (nested) > + nested->prev_cpu[vcpu->arch.nested_vcpu_id] =3D pcpu; > + else > + vcpu->arch.prev_cpu =3D pcpu; > + } > +} > + > +static void kvmppc_radix_check_need_tlb_flush(struct kvm *kvm, int pcpu, > + struct kvm_nested_guest *nested) > +{ > + cpumask_t *need_tlb_flush; > + int lpid; > + > + if (!cpu_has_feature(CPU_FTR_HVMODE)) > + return; > + > + if (cpu_has_feature(CPU_FTR_ARCH_300)) > + pcpu &=3D ~0x3UL; > + > + if (nested) { > + lpid =3D nested->shadow_lpid; > + need_tlb_flush =3D &nested->need_tlb_flush; > + } else { > + lpid =3D kvm->arch.lpid; > + need_tlb_flush =3D &kvm->arch.need_tlb_flush; > + } > + > + mtspr(SPRN_LPID, lpid); > + isync(); > + smp_mb(); > + > + if (cpumask_test_cpu(pcpu, need_tlb_flush)) { > + radix__local_flush_tlb_lpid_guest(lpid); > + /* Clear the bit after the TLB flush */ > + cpumask_clear_cpu(pcpu, need_tlb_flush); > } > } > =20 > @@ -3127,8 +3179,6 @@ static noinline void kvmppc_run_core(struct kvmppc_= vcore *vc) > spin_unlock(&core_info.vc[sub]->lock); > =20 > if (kvm_is_radix(vc->kvm)) { > - int tmp =3D pcpu; > - > /* > * Do we need to flush the process scoped TLB for the LPAR? > * > @@ -3139,17 +3189,7 @@ static noinline void kvmppc_run_core(struct kvmppc= _vcore *vc) > * > * Hash must be flushed in realmode in order to use tlbiel. > */ > - mtspr(SPRN_LPID, vc->kvm->arch.lpid); > - isync(); > - > - if (cpu_has_feature(CPU_FTR_ARCH_300)) > - tmp &=3D ~0x3UL; > - > - if (cpumask_test_cpu(tmp, &vc->kvm->arch.need_tlb_flush)) { > - radix__local_flush_tlb_lpid_guest(vc->kvm->arch.lpid); > - /* Clear the bit after the TLB flush */ > - cpumask_clear_cpu(tmp, &vc->kvm->arch.need_tlb_flush); > - } > + kvmppc_radix_check_need_tlb_flush(vc->kvm, pcpu, NULL); > } > =20 > /* > @@ -3868,11 +3908,10 @@ int kvmhv_run_single_vcpu(struct kvm_run *kvm_run, > struct kvm_vcpu *vcpu, u64 time_limit, > unsigned long lpcr) > { > - int trap, r, pcpu, pcpu0; > + int trap, r, pcpu; > int srcu_idx; > struct kvmppc_vcore *vc; > struct kvm_nested_guest *nested =3D vcpu->arch.nested; > - unsigned long lpid; > =20 > trace_kvmppc_run_vcpu_enter(vcpu); > =20 > @@ -3945,22 +3984,8 @@ int kvmhv_run_single_vcpu(struct kvm_run *kvm_run, > vc->vcore_state =3D VCORE_RUNNING; > trace_kvmppc_run_core(vc, 0); > =20 > - lpid =3D vc->kvm->arch.lpid; > - if (nested) > - lpid =3D nested->shadow_lpid; > - mtspr(SPRN_LPID, lpid); > - isync(); > - > - /* See comment above in kvmppc_run_core() about this */ > - pcpu0 =3D pcpu; > - if (cpu_has_feature(CPU_FTR_ARCH_300)) > - pcpu0 &=3D ~0x3UL; > - > - if (cpumask_test_cpu(pcpu0, &vc->kvm->arch.need_tlb_flush)) { > - radix__local_flush_tlb_lpid_guest(lpid); > - /* Clear the bit after the TLB flush */ > - cpumask_clear_cpu(pcpu0, &vc->kvm->arch.need_tlb_flush); > - } > + if (cpu_has_feature(CPU_FTR_HVMODE)) > + kvmppc_radix_check_need_tlb_flush(vc->kvm, pcpu, nested); > =20 > trace_hardirqs_on(); > guest_enter_irqoff(); > diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3= s_hv_nested.c > index 35f8111..1a8c40d 100644 > --- a/arch/powerpc/kvm/book3s_hv_nested.c > +++ b/arch/powerpc/kvm/book3s_hv_nested.c > @@ -167,6 +167,9 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu) > if (err) > return H_PARAMETER; > =20 > + if (l2_hv.vcpu_token >=3D NR_CPUS) > + return H_PARAMETER; > + > /* translate lpid */ > l2 =3D kvmhv_get_nested(vcpu->kvm, l2_hv.lpid, true); > if (!l2) > @@ -411,6 +414,8 @@ struct kvm_nested_guest *kvmhv_alloc_nested(struct kv= m *kvm, unsigned int lpid) > goto out_free2; > gp->shadow_lpid =3D shadow_lpid; > =20 > + memset(gp->prev_cpu, -1, sizeof(gp->prev_cpu)); > + > return gp; > =20 > out_free2: --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --sdEQJo40s7ofW8iR Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAlu24+EACgkQbDjKyiDZ s5I1XhAAr10Pm3cgEDm4Yr5N83SakRnlq0gTqkCfVOZ8xBzGhH0KMbTIuek3cV+F 5aBZ7LquNB+/EMz0LNdXKsNrd2vX4638bX2uRlnPPlA6OyJLQgmfyK+At3EYUMf+ QidAiFW1/MWfTrEOmmd77XeotzVL8zxoph7KtYtxy9bKcVAJyq+g7Hfya3nErweq 72knnL/O4H18m7vOtSTSBrbpccuBymSvd2sd9IHWBFPHZsrjeuqIZXizfxYtsxKK RN1ALH8wPsRjgh2cMfLsCK0tB5jszJUas+bB3CvRPbQewEcS3c5tAqJKJsGbC78r bW53Ut0JmNohaQV28/iKWMWSwbQ2aSAE4CdE+ZQrzhaQftIM8u5SnA+ACNzm98xn gjkBHzPSMZ98/1ClPdRlohRvB7YcqgqMB1ELJdPscXCL1yRlxrcYiwMh4wpx3qbb xTegPorjOFOxuXi7zrRGQ5wcO9RALkYwBqlBSEq2HwubAkPsNS2kpyn0y3Il82Lu G+I3XyUo56Aok+jOSf17MNTa1biTvS6LHCFUrI/006kP5btu0jidre+9VLV/J563 CokYPCGHBv+coz8ISa3httYv8TXCSw6XxxgBxsa3GAf975nZR6mc6q3TD0bRGMeG tRqSfsg5iNd2eoSbYDzjJC/Aeze0GGOUL77+qsVjy0n/mhMHh+0= =gTQn -----END PGP SIGNATURE----- --sdEQJo40s7ofW8iR-- From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Gibson Date: Fri, 05 Oct 2018 04:09:08 +0000 Subject: Re: [PATCH v4 25/32] KVM: PPC: Book3S HV: Invalidate TLB when nested vcpu moves physical cpu Message-Id: <20181005040908.GK7004@umbus.fritz.box> MIME-Version: 1 Content-Type: multipart/mixed; boundary="sdEQJo40s7ofW8iR" List-Id: References: <1538654169-15602-1-git-send-email-paulus@ozlabs.org> <1538654169-15602-26-git-send-email-paulus@ozlabs.org> In-Reply-To: <1538654169-15602-26-git-send-email-paulus@ozlabs.org> To: Paul Mackerras Cc: linuxppc-dev@ozlabs.org, kvm-ppc@vger.kernel.org, kvm@vger.kernel.org --sdEQJo40s7ofW8iR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Oct 04, 2018 at 09:56:02PM +1000, Paul Mackerras wrote: > From: Suraj Jitindar Singh >=20 > This is only done at level 0, since only level 0 knows which physical > CPU a vcpu is running on. This does for nested guests what L0 already > did for its own guests, which is to flush the TLB on a pCPU when it > goes to run a vCPU there, and there is another vCPU in the same VM > which previously ran on this pCPU and has now started to run on another > pCPU. This is to handle the situation where the other vCPU touched > a mapping, moved to another pCPU and did a tlbiel (local-only tlbie) > on that new pCPU and thus left behind a stale TLB entry on this pCPU. >=20 > This introduces a limit on the the vcpu_token values used in the > H_ENTER_NESTED hcall -- they must now be less than NR_CPUS. This does make the vcpu tokens no longer entirely opaque to the L0. It works for now, because the only L1 is Linux and we know basically how it allocates those tokens. Eventually we probably want some way to either remove this restriction or to advertise the limit to the L1. > [paulus@ozlabs.org - made prev_cpu array be unsigned short[] to reduce > memory consumption.] >=20 > Signed-off-by: Suraj Jitindar Singh > Signed-off-by: Paul Mackerras Reviewed-by: David Gibson > --- > arch/powerpc/include/asm/kvm_book3s_64.h | 3 + > arch/powerpc/kvm/book3s_hv.c | 101 +++++++++++++++++++------= ------ > arch/powerpc/kvm/book3s_hv_nested.c | 5 ++ > 3 files changed, 71 insertions(+), 38 deletions(-) >=20 > diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/incl= ude/asm/kvm_book3s_64.h > index aa5bf85..1e96027 100644 > --- a/arch/powerpc/include/asm/kvm_book3s_64.h > +++ b/arch/powerpc/include/asm/kvm_book3s_64.h > @@ -52,6 +52,9 @@ struct kvm_nested_guest { > long refcnt; /* number of pointers to this struct */ > struct mutex tlb_lock; /* serialize page faults and tlbies */ > struct kvm_nested_guest *next; > + cpumask_t need_tlb_flush; > + cpumask_t cpu_in_guest; > + unsigned short prev_cpu[NR_CPUS]; > }; > =20 > /* > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index ba58883..53a967ea 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -2397,10 +2397,18 @@ static void kvmppc_release_hwthread(int cpu) > =20 > static void radix_flush_cpu(struct kvm *kvm, int cpu, struct kvm_vcpu *v= cpu) > { > + struct kvm_nested_guest *nested =3D vcpu->arch.nested; > + cpumask_t *cpu_in_guest; > int i; > =20 > cpu =3D cpu_first_thread_sibling(cpu); > - cpumask_set_cpu(cpu, &kvm->arch.need_tlb_flush); > + if (nested) { > + cpumask_set_cpu(cpu, &nested->need_tlb_flush); > + cpu_in_guest =3D &nested->cpu_in_guest; > + } else { > + cpumask_set_cpu(cpu, &kvm->arch.need_tlb_flush); > + cpu_in_guest =3D &kvm->arch.cpu_in_guest; > + } > /* > * Make sure setting of bit in need_tlb_flush precedes > * testing of cpu_in_guest bits. The matching barrier on > @@ -2408,13 +2416,23 @@ static void radix_flush_cpu(struct kvm *kvm, int = cpu, struct kvm_vcpu *vcpu) > */ > smp_mb(); > for (i =3D 0; i < threads_per_core; ++i) > - if (cpumask_test_cpu(cpu + i, &kvm->arch.cpu_in_guest)) > + if (cpumask_test_cpu(cpu + i, cpu_in_guest)) > smp_call_function_single(cpu + i, do_nothing, NULL, 1); > } > =20 > static void kvmppc_prepare_radix_vcpu(struct kvm_vcpu *vcpu, int pcpu) > { > + struct kvm_nested_guest *nested =3D vcpu->arch.nested; > struct kvm *kvm =3D vcpu->kvm; > + int prev_cpu; > + > + if (!cpu_has_feature(CPU_FTR_HVMODE)) > + return; > + > + if (nested) > + prev_cpu =3D nested->prev_cpu[vcpu->arch.nested_vcpu_id]; > + else > + prev_cpu =3D vcpu->arch.prev_cpu; > =20 > /* > * With radix, the guest can do TLB invalidations itself, > @@ -2428,12 +2446,46 @@ static void kvmppc_prepare_radix_vcpu(struct kvm_= vcpu *vcpu, int pcpu) > * ran to flush the TLB. The TLB is shared between threads, > * so we use a single bit in .need_tlb_flush for all 4 threads. > */ > - if (vcpu->arch.prev_cpu !=3D pcpu) { > - if (vcpu->arch.prev_cpu >=3D 0 && > - cpu_first_thread_sibling(vcpu->arch.prev_cpu) !=3D > + if (prev_cpu !=3D pcpu) { > + if (prev_cpu >=3D 0 && > + cpu_first_thread_sibling(prev_cpu) !=3D > cpu_first_thread_sibling(pcpu)) > - radix_flush_cpu(kvm, vcpu->arch.prev_cpu, vcpu); > - vcpu->arch.prev_cpu =3D pcpu; > + radix_flush_cpu(kvm, prev_cpu, vcpu); > + if (nested) > + nested->prev_cpu[vcpu->arch.nested_vcpu_id] =3D pcpu; > + else > + vcpu->arch.prev_cpu =3D pcpu; > + } > +} > + > +static void kvmppc_radix_check_need_tlb_flush(struct kvm *kvm, int pcpu, > + struct kvm_nested_guest *nested) > +{ > + cpumask_t *need_tlb_flush; > + int lpid; > + > + if (!cpu_has_feature(CPU_FTR_HVMODE)) > + return; > + > + if (cpu_has_feature(CPU_FTR_ARCH_300)) > + pcpu &=3D ~0x3UL; > + > + if (nested) { > + lpid =3D nested->shadow_lpid; > + need_tlb_flush =3D &nested->need_tlb_flush; > + } else { > + lpid =3D kvm->arch.lpid; > + need_tlb_flush =3D &kvm->arch.need_tlb_flush; > + } > + > + mtspr(SPRN_LPID, lpid); > + isync(); > + smp_mb(); > + > + if (cpumask_test_cpu(pcpu, need_tlb_flush)) { > + radix__local_flush_tlb_lpid_guest(lpid); > + /* Clear the bit after the TLB flush */ > + cpumask_clear_cpu(pcpu, need_tlb_flush); > } > } > =20 > @@ -3127,8 +3179,6 @@ static noinline void kvmppc_run_core(struct kvmppc_= vcore *vc) > spin_unlock(&core_info.vc[sub]->lock); > =20 > if (kvm_is_radix(vc->kvm)) { > - int tmp =3D pcpu; > - > /* > * Do we need to flush the process scoped TLB for the LPAR? > * > @@ -3139,17 +3189,7 @@ static noinline void kvmppc_run_core(struct kvmppc= _vcore *vc) > * > * Hash must be flushed in realmode in order to use tlbiel. > */ > - mtspr(SPRN_LPID, vc->kvm->arch.lpid); > - isync(); > - > - if (cpu_has_feature(CPU_FTR_ARCH_300)) > - tmp &=3D ~0x3UL; > - > - if (cpumask_test_cpu(tmp, &vc->kvm->arch.need_tlb_flush)) { > - radix__local_flush_tlb_lpid_guest(vc->kvm->arch.lpid); > - /* Clear the bit after the TLB flush */ > - cpumask_clear_cpu(tmp, &vc->kvm->arch.need_tlb_flush); > - } > + kvmppc_radix_check_need_tlb_flush(vc->kvm, pcpu, NULL); > } > =20 > /* > @@ -3868,11 +3908,10 @@ int kvmhv_run_single_vcpu(struct kvm_run *kvm_run, > struct kvm_vcpu *vcpu, u64 time_limit, > unsigned long lpcr) > { > - int trap, r, pcpu, pcpu0; > + int trap, r, pcpu; > int srcu_idx; > struct kvmppc_vcore *vc; > struct kvm_nested_guest *nested =3D vcpu->arch.nested; > - unsigned long lpid; > =20 > trace_kvmppc_run_vcpu_enter(vcpu); > =20 > @@ -3945,22 +3984,8 @@ int kvmhv_run_single_vcpu(struct kvm_run *kvm_run, > vc->vcore_state =3D VCORE_RUNNING; > trace_kvmppc_run_core(vc, 0); > =20 > - lpid =3D vc->kvm->arch.lpid; > - if (nested) > - lpid =3D nested->shadow_lpid; > - mtspr(SPRN_LPID, lpid); > - isync(); > - > - /* See comment above in kvmppc_run_core() about this */ > - pcpu0 =3D pcpu; > - if (cpu_has_feature(CPU_FTR_ARCH_300)) > - pcpu0 &=3D ~0x3UL; > - > - if (cpumask_test_cpu(pcpu0, &vc->kvm->arch.need_tlb_flush)) { > - radix__local_flush_tlb_lpid_guest(lpid); > - /* Clear the bit after the TLB flush */ > - cpumask_clear_cpu(pcpu0, &vc->kvm->arch.need_tlb_flush); > - } > + if (cpu_has_feature(CPU_FTR_HVMODE)) > + kvmppc_radix_check_need_tlb_flush(vc->kvm, pcpu, nested); > =20 > trace_hardirqs_on(); > guest_enter_irqoff(); > diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3= s_hv_nested.c > index 35f8111..1a8c40d 100644 > --- a/arch/powerpc/kvm/book3s_hv_nested.c > +++ b/arch/powerpc/kvm/book3s_hv_nested.c > @@ -167,6 +167,9 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu) > if (err) > return H_PARAMETER; > =20 > + if (l2_hv.vcpu_token >=3D NR_CPUS) > + return H_PARAMETER; > + > /* translate lpid */ > l2 =3D kvmhv_get_nested(vcpu->kvm, l2_hv.lpid, true); > if (!l2) > @@ -411,6 +414,8 @@ struct kvm_nested_guest *kvmhv_alloc_nested(struct kv= m *kvm, unsigned int lpid) > goto out_free2; > gp->shadow_lpid =3D shadow_lpid; > =20 > + memset(gp->prev_cpu, -1, sizeof(gp->prev_cpu)); > + > return gp; > =20 > out_free2: --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. 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