| Message ID | 1491218595-10943-1-git-send-email-thuth@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Apr 03, 2017 at 01:23:15PM +0200, Thomas Huth wrote: > According to the PowerISA 2.07, mtspr and mfspr should not generate > an illegal instruction exception when being used with an undefined SPR, > but rather treat the instruction as a NOP, inject a privilege exception > or an emulation assistance exception - depending on the SPR number. The emulation assist interrupt is a hypervisor interrupt, so the guest would not be expecting to receive it. On a real machine, the hypervisor would synthesize an illegal instruction type program interrupt as described in the last programming note in section 6.5.9 of Book III of Power ISA v2.07B. Since we are the hypervisor here, we should synthesize a program interrupt rather than an emulation assist interrupt. > 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. Good idea. Paul.
On 04.04.2017 08:25, Paul Mackerras wrote: > On Mon, Apr 03, 2017 at 01:23:15PM +0200, Thomas Huth wrote: >> According to the PowerISA 2.07, mtspr and mfspr should not generate >> an illegal instruction exception when being used with an undefined SPR, >> but rather treat the instruction as a NOP, inject a privilege exception >> or an emulation assistance exception - depending on the SPR number. > > The emulation assist interrupt is a hypervisor interrupt, so the guest > would not be expecting to receive it. On a real machine, the > hypervisor would synthesize an illegal instruction type program > interrupt as described in the last programming note in section 6.5.9 > of Book III of Power ISA v2.07B. Since we are the hypervisor here, we > should synthesize a program interrupt rather than an emulation assist > interrupt. Ah, right, we're doing this in other spots, too, so a PROGILL is indeed more consistent here. I'll send a v2 ... Thomas
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c index b6b5c18..9b007f9 100644 --- a/arch/powerpc/kvm/book3s.c +++ b/arch/powerpc/kvm/book3s.c @@ -137,6 +137,7 @@ void kvmppc_inject_interrupt(struct kvm_vcpu *vcpu, int vec, u64 flags) kvmppc_set_pc(vcpu, kvmppc_interrupt_offset(vcpu) + vec); vcpu->arch.mmu.reset_msr(vcpu); } +EXPORT_SYMBOL_GPL(kvmppc_inject_interrupt); static int kvmppc_book3s_vec2irqprio(unsigned int vec) { diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c index 8359752..9c31e23 100644 --- a/arch/powerpc/kvm/book3s_emulate.c +++ b/arch/powerpc/kvm/book3s_emulate.c @@ -503,10 +503,16 @@ 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); + } else { + if ((kvmppc_get_msr(vcpu) & MSR_PR) || sprn == 0) + kvmppc_inject_interrupt(vcpu, + BOOK3S_INTERRUPT_H_EMUL_ASSIST, + 0); + } break; } @@ -648,10 +654,18 @@ 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); + } else { + if ((kvmppc_get_msr(vcpu) & MSR_PR) || sprn == 0 || + sprn == 4 || sprn == 5 || sprn == 6) + kvmppc_inject_interrupt(vcpu, + BOOK3S_INTERRUPT_H_EMUL_ASSIST, + 0); + } + break; }
According to the PowerISA 2.07, mtspr and mfspr should not generate an illegal instruction exception when being used with an undefined SPR, but rather treat the instruction as a NOP, inject a privilege exception or an emulation assistance exception - 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 <thuth@redhat.com> --- arch/powerpc/kvm/book3s.c | 1 + arch/powerpc/kvm/book3s_emulate.c | 30 ++++++++++++++++++++++-------- 2 files changed, 23 insertions(+), 8 deletions(-)