On 05.04.2017 15:58, 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@xxxxxxxxxx>
> ---
> 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:
>
Ping!
Paul, does this now look OK for you this way?
Thomas
