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[58.6.239.121]) by smtp.gmail.com with ESMTPSA id jt21sm497062pjb.51.2021.03.08.17.14.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Mar 2021 17:14:15 -0800 (PST) Date: Tue, 09 Mar 2021 11:14:10 +1000 From: Nicholas Piggin Subject: Re: [PATCH v3 02/41] KVM: PPC: Book3S HV: Prevent radix guests from setting LPCR[TC] To: Fabiano Rosas , kvm-ppc@vger.kernel.org References: <20210305150638.2675513-1-npiggin@gmail.com> <20210305150638.2675513-3-npiggin@gmail.com> <878s6xmyv4.fsf@linux.ibm.com> In-Reply-To: <878s6xmyv4.fsf@linux.ibm.com> MIME-Version: 1.0 Message-Id: <1615252361.wjh446wma8.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Excerpts from Fabiano Rosas's message of March 9, 2021 1:47 am: > Nicholas Piggin writes: >=20 >> This bit only applies to hash partitions. >> >> Signed-off-by: Nicholas Piggin >> --- >> arch/powerpc/kvm/book3s_hv.c | 6 ++++-- >> arch/powerpc/kvm/book3s_hv_nested.c | 2 +- >> 2 files changed, 5 insertions(+), 3 deletions(-) >> >> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c >> index c40eeb20be39..2e29b96ef775 100644 >> --- a/arch/powerpc/kvm/book3s_hv.c >> +++ b/arch/powerpc/kvm/book3s_hv.c >> @@ -1666,10 +1666,12 @@ static void kvmppc_set_lpcr(struct kvm_vcpu *vcp= u, u64 new_lpcr, >> >> /* >> * Userspace can only modify DPFD (default prefetch depth), >> - * ILE (interrupt little-endian) and TC (translation control). >> + * ILE (interrupt little-endian) and TC (translation control) if HPT. >> * On POWER8 and POWER9 userspace can also modify AIL (alt. interrupt = loc.). >> */ >> - mask =3D LPCR_DPFD | LPCR_ILE | LPCR_TC; >> + mask =3D LPCR_DPFD | LPCR_ILE; >> + if (!kvm_is_radix(kvm)) >> + mask |=3D LPCR_TC; >=20 > I think in theory there is a possibility that userspace sets the LPCR > while we running Radix and then calls the KVM_PPC_CONFIGURE_V3_MMU ioctl > right after to switch to HPT. I'm not sure if that would make sense but > maybe it's something to consider... Oh actually it is an issue for the later AIL patch I think. So LPCR will have to be filtered again when switching MMU mode. Good catch, I'll add something for that. Thanks, Nick >=20 >> if (cpu_has_feature(CPU_FTR_ARCH_207S)) { >> mask |=3D LPCR_AIL; >> /* LPCR[AIL]=3D1/2 is disallowed */ >> diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book= 3s_hv_nested.c >> index b496079e02f7..0e6cf650cbfe 100644 >> --- a/arch/powerpc/kvm/book3s_hv_nested.c >> +++ b/arch/powerpc/kvm/book3s_hv_nested.c >> @@ -141,7 +141,7 @@ static void sanitise_hv_regs(struct kvm_vcpu *vcpu, = struct hv_guest_state *hr) >> * Don't let L1 change LPCR bits for the L2 except these: >> * Keep this in sync with kvmppc_set_lpcr. >> */ >> - mask =3D LPCR_DPFD | LPCR_ILE | LPCR_TC | LPCR_LD | LPCR_LPES | LPCR_M= ER; >> + mask =3D LPCR_DPFD | LPCR_ILE | LPCR_LD | LPCR_LPES | LPCR_MER; >> /* LPCR[AIL]=3D1/2 is disallowed */ >> if ((hr->lpcr & LPCR_AIL) && (hr->lpcr & LPCR_AIL) !=3D LPCR_AIL_3) >> hr->lpcr &=3D ~LPCR_AIL; >=20