From afe75049303f75c73a97d635a4d353c7d571d1a3 Mon Sep 17 00:00:00 2001 From: Ravi Bangoria Date: Wed, 16 Dec 2020 16:12:16 +0530 Subject: [PATCH] KVM: PPC: Book3S HV: Allow nested guest creation when L0 hv_guest_state > L1 On powerpc, L1 hypervisor takes help of L0 using H_ENTER_NESTED hcall to load L2 guest state in cpu. L1 hypervisor prepares the L2 state in struct hv_guest_state and passes a pointer to it via hcall. Using that pointer, L0 reads/writes that state directly from/to L1 memory. Thus L0 must be aware of hv_guest_state layout of L1. Currently it uses version field to achieve this. i.e. If L0 hv_guest_state.version != L1 hv_guest_state.version, L0 won't allow nested kvm guest. This restriction can be loosened up a bit. L0 can be taught to understand older layout of hv_guest_state, if we restrict the new members to be added only at the end, i.e. we can allow nested guest even when L0 hv_guest_state.version > L1 hv_guest_state.version. Though, the other way around is not possible. Signed-off-by: Ravi Bangoria Reviewed-by: Fabiano Rosas Signed-off-by: Paul Mackerras --- arch/powerpc/include/asm/hvcall.h | 17 ++++++++++-- arch/powerpc/kvm/book3s_hv_nested.c | 55 ++++++++++++++++++++++++++++++------- 2 files changed, 60 insertions(+), 12 deletions(-) diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h index c98f514..cb4d07e 100644 --- a/arch/powerpc/include/asm/hvcall.h +++ b/arch/powerpc/include/asm/hvcall.h @@ -535,9 +535,12 @@ struct h_cpu_char_result { u64 behaviour; }; -/* Register state for entering a nested guest with H_ENTER_NESTED */ +/* + * Register state for entering a nested guest with H_ENTER_NESTED. + * New member must be added at the end. + */ struct hv_guest_state { - u64 version; /* version of this structure layout */ + u64 version; /* version of this structure layout, must be first */ u32 lpid; u32 vcpu_token; /* These registers are hypervisor privileged (at least for writing) */ @@ -571,6 +574,16 @@ struct hv_guest_state { /* Latest version of hv_guest_state structure */ #define HV_GUEST_STATE_VERSION 1 +static inline int hv_guest_state_size(unsigned int version) +{ + switch (version) { + case 1: + return offsetofend(struct hv_guest_state, ppr); + default: + return -1; + } +} + /* * From the document "H_GetPerformanceCounterInfo Interface" v1.07 * diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c index 33b5854..5b8043c 100644 --- a/arch/powerpc/kvm/book3s_hv_nested.c +++ b/arch/powerpc/kvm/book3s_hv_nested.c @@ -215,12 +215,51 @@ static void kvmhv_nested_mmio_needed(struct kvm_vcpu *vcpu, u64 regs_ptr) } } +static int kvmhv_read_guest_state_and_regs(struct kvm_vcpu *vcpu, + struct hv_guest_state *l2_hv, + struct pt_regs *l2_regs, + u64 hv_ptr, u64 regs_ptr) +{ + int size; + + if (kvm_vcpu_read_guest(vcpu, hv_ptr, &l2_hv->version, + sizeof(l2_hv->version))) + return -1; + + if (kvmppc_need_byteswap(vcpu)) + l2_hv->version = swab64(l2_hv->version); + + size = hv_guest_state_size(l2_hv->version); + if (size < 0) + return -1; + + return kvm_vcpu_read_guest(vcpu, hv_ptr, l2_hv, size) || + kvm_vcpu_read_guest(vcpu, regs_ptr, l2_regs, + sizeof(struct pt_regs)); +} + +static int kvmhv_write_guest_state_and_regs(struct kvm_vcpu *vcpu, + struct hv_guest_state *l2_hv, + struct pt_regs *l2_regs, + u64 hv_ptr, u64 regs_ptr) +{ + int size; + + size = hv_guest_state_size(l2_hv->version); + if (size < 0) + return -1; + + return kvm_vcpu_write_guest(vcpu, hv_ptr, l2_hv, size) || + kvm_vcpu_write_guest(vcpu, regs_ptr, l2_regs, + sizeof(struct pt_regs)); +} + long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu) { long int err, r; struct kvm_nested_guest *l2; struct pt_regs l2_regs, saved_l1_regs; - struct hv_guest_state l2_hv, saved_l1_hv; + struct hv_guest_state l2_hv = {0}, saved_l1_hv; struct kvmppc_vcore *vc = vcpu->arch.vcore; u64 hv_ptr, regs_ptr; u64 hdec_exp; @@ -235,17 +274,15 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu) hv_ptr = kvmppc_get_gpr(vcpu, 4); regs_ptr = kvmppc_get_gpr(vcpu, 5); vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); - err = kvm_vcpu_read_guest(vcpu, hv_ptr, &l2_hv, - sizeof(struct hv_guest_state)) || - kvm_vcpu_read_guest(vcpu, regs_ptr, &l2_regs, - sizeof(struct pt_regs)); + err = kvmhv_read_guest_state_and_regs(vcpu, &l2_hv, &l2_regs, + hv_ptr, regs_ptr); srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); if (err) return H_PARAMETER; if (kvmppc_need_byteswap(vcpu)) byteswap_hv_regs(&l2_hv); - if (l2_hv.version != HV_GUEST_STATE_VERSION) + if (l2_hv.version > HV_GUEST_STATE_VERSION) return H_P2; if (kvmppc_need_byteswap(vcpu)) @@ -325,10 +362,8 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu) byteswap_pt_regs(&l2_regs); } vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); - err = kvm_vcpu_write_guest(vcpu, hv_ptr, &l2_hv, - sizeof(struct hv_guest_state)) || - kvm_vcpu_write_guest(vcpu, regs_ptr, &l2_regs, - sizeof(struct pt_regs)); + err = kvmhv_write_guest_state_and_regs(vcpu, &l2_hv, &l2_regs, + hv_ptr, regs_ptr); srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); if (err) return H_AUTHORITY; -- 2.7.4