Re: [PATCH v3 02/41] KVM: PPC: Book3S HV: Prevent radix guests from setting LPCR[TC]
From: Fabiano Rosas <hidden>
Date: 2021-03-08 15:47:48
Nicholas Piggin [off-list ref] writes:
quoted hunk ↗ jump to hunk
This bit only applies to hash partitions. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- 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 *vcpu, 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 = LPCR_DPFD | LPCR_ILE | LPCR_TC; + mask = LPCR_DPFD | LPCR_ILE; + if (!kvm_is_radix(kvm)) + mask |= LPCR_TC;
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...
quoted hunk ↗ jump to hunk
if (cpu_has_feature(CPU_FTR_ARCH_207S)) { mask |= LPCR_AIL; /* LPCR[AIL]=1/2 is disallowed */diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_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 = LPCR_DPFD | LPCR_ILE | LPCR_TC | LPCR_LD | LPCR_LPES | LPCR_MER; + mask = LPCR_DPFD | LPCR_ILE | LPCR_LD | LPCR_LPES | LPCR_MER; /* LPCR[AIL]=1/2 is disallowed */ if ((hr->lpcr & LPCR_AIL) && (hr->lpcr & LPCR_AIL) != LPCR_AIL_3) hr->lpcr &= ~LPCR_AIL;