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Tue, 24 Nov 2020 11:00:12 +0000 (GMT) From: Ravi Bangoria To: mpe@ellerman.id.au, paulus@samba.org Subject: [PATCH v2 1/4] KVM: PPC: Allow nested guest creation when L0 hv_guest_state > L1 Date: Tue, 24 Nov 2020 16:29:50 +0530 Message-Id: <20201124105953.39325-2-ravi.bangoria@linux.ibm.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201124105953.39325-1-ravi.bangoria@linux.ibm.com> References: <20201124105953.39325-1-ravi.bangoria@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312, 18.0.737 definitions=2020-11-24_04:2020-11-24, 2020-11-23 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 suspectscore=0 mlxlogscore=999 spamscore=0 priorityscore=1501 mlxscore=0 phishscore=0 clxscore=1015 impostorscore=0 bulkscore=0 adultscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011240061 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: christophe.leroy@c-s.fr, ravi.bangoria@linux.ibm.com, mikey@neuling.org, kvm@vger.kernel.org, leobras.c@gmail.com, jniethe5@gmail.com, linux-kernel@vger.kernel.org, npiggin@gmail.com, kvm-ppc@vger.kernel.org, pbonzini@redhat.com, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 loosen up a bit. L0 can be taught to understand older layout of hv_guest_state, if we restrict the new member 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 --- arch/powerpc/include/asm/hvcall.h | 17 +++++++-- arch/powerpc/kvm/book3s_hv_nested.c | 53 ++++++++++++++++++++++++----- 2 files changed, 59 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h index fbb377055471..a7073fddb657 100644 --- a/arch/powerpc/include/asm/hvcall.h +++ b/arch/powerpc/include/asm/hvcall.h @@ -524,9 +524,12 @@ 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) */ @@ -560,6 +563,16 @@ 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; + } +} + #endif /* __ASSEMBLY__ */ #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_HVCALL_H */ diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c index 33b58549a9aa..2b433c3bacea 100644 --- a/arch/powerpc/kvm/book3s_hv_nested.c +++ b/arch/powerpc/kvm/book3s_hv_nested.c @@ -215,6 +215,45 @@ 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; @@ -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;