| Message ID | 1491300303-16153-1-git-send-email-thuth@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Apr 04, 2017 at 12:05:03PM +0200, Thomas Huth wrote: > 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 <thuth@redhat.com> > --- > 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 | 26 ++++++++++++++++++-------- > 1 file changed, 18 insertions(+), 8 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c > index 8359752..bf4181e 100644 > --- a/arch/powerpc/kvm/book3s_emulate.c > +++ b/arch/powerpc/kvm/book3s_emulate.c > @@ -503,10 +503,14 @@ 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_core_queue_program(vcpu, SRR1_PROGILL); > + } > break; In the cases where we generate an interrupt, we are now returning EMULATE_DONE, which means that kvmppc_emulate_instruction() will advance the PC by 4 after this function returns. Since kvmppc_core_queue_program() injects the interrupt straight away, this means that the guest will resume execution at 0x704 rather than 0x700. Paul.
diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c index 8359752..bf4181e 100644 --- a/arch/powerpc/kvm/book3s_emulate.c +++ b/arch/powerpc/kvm/book3s_emulate.c @@ -503,10 +503,14 @@ 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_core_queue_program(vcpu, SRR1_PROGILL); + } break; } @@ -648,10 +652,16 @@ 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_core_queue_program(vcpu, SRR1_PROGILL); + } + break; }
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 <thuth@redhat.com> --- 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 | 26 ++++++++++++++++++-------- 1 file changed, 18 insertions(+), 8 deletions(-)