From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3vynWM1mdszDqH6 for ; Wed, 5 Apr 2017 23:58:55 +1000 (AEST) From: Thomas Huth To: Paul Mackerras , kvm-ppc@vger.kernel.org Cc: kvm@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: [PATCH v3] KVM: PPC: Book3S PR: Do not fail emulation with mtspr/mfspr for unknown SPRs Date: Wed, 5 Apr 2017 15:58:51 +0200 Message-Id: <1491400731-2492-1-git-send-email-thuth@redhat.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , According to the PowerISA 2.07, mtspr and mfspr should not always generate an illegal instruction exception when being used with an undefined SPR, but rather treat the instruction as a NOP or inject a privilege exception in some cases, too - depending on the SPR number. Also turn the printk here into a ratelimited print statement, so that the guest can not flood the dmesg log of the host by issueing lots of illegal mtspr/mfspr instruction here. Signed-off-by: Thomas Huth --- v3: - Make sure that we do not advance the program counter after we've already changed it due to injecting a program interrupt v2: - Inject illegal instruction program interrupt instead of emulation assist interrupt (according to the last programming note in section 6.5.9 of Book III of the PowerISA v2.07) arch/powerpc/kvm/book3s_emulate.c | 34 ++++++++++++++++++++++++++-------- arch/powerpc/kvm/emulate.c | 8 ++++++++ 2 files changed, 34 insertions(+), 8 deletions(-) diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c index 8359752..68d6898 100644 --- a/arch/powerpc/kvm/book3s_emulate.c +++ b/arch/powerpc/kvm/book3s_emulate.c @@ -503,10 +503,18 @@ int kvmppc_core_emulate_mtspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val) break; unprivileged: default: - printk(KERN_INFO "KVM: invalid SPR write: %d\n", sprn); -#ifndef DEBUG_SPR - emulated = EMULATE_FAIL; -#endif + pr_info_ratelimited("KVM: invalid SPR write: %d\n", sprn); + if (sprn & 0x10) { + if (kvmppc_get_msr(vcpu) & MSR_PR) { + kvmppc_core_queue_program(vcpu, SRR1_PROGPRIV); + emulated = EMULATE_AGAIN; + } + } else { + if ((kvmppc_get_msr(vcpu) & MSR_PR) || sprn == 0) { + kvmppc_core_queue_program(vcpu, SRR1_PROGILL); + emulated = EMULATE_AGAIN; + } + } break; } @@ -648,10 +656,20 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val break; default: unprivileged: - printk(KERN_INFO "KVM: invalid SPR read: %d\n", sprn); -#ifndef DEBUG_SPR - emulated = EMULATE_FAIL; -#endif + pr_info_ratelimited("KVM: invalid SPR read: %d\n", sprn); + if (sprn & 0x10) { + if (kvmppc_get_msr(vcpu) & MSR_PR) { + kvmppc_core_queue_program(vcpu, SRR1_PROGPRIV); + emulated = EMULATE_AGAIN; + } + } else { + if ((kvmppc_get_msr(vcpu) & MSR_PR) || sprn == 0 || + sprn == 4 || sprn == 5 || sprn == 6) { + kvmppc_core_queue_program(vcpu, SRR1_PROGILL); + emulated = EMULATE_AGAIN; + } + } + break; } diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c index b379146..c873ffe 100644 --- a/arch/powerpc/kvm/emulate.c +++ b/arch/powerpc/kvm/emulate.c @@ -259,10 +259,18 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu) case OP_31_XOP_MFSPR: emulated = kvmppc_emulate_mfspr(vcpu, sprn, rt); + if (emulated == EMULATE_AGAIN) { + emulated = EMULATE_DONE; + advance = 0; + } break; case OP_31_XOP_MTSPR: emulated = kvmppc_emulate_mtspr(vcpu, sprn, rs); + if (emulated == EMULATE_AGAIN) { + emulated = EMULATE_DONE; + advance = 0; + } break; case OP_31_XOP_TLBSYNC: -- 1.8.3.1