Re: [PATCH v2 17/30] KVM: PPC: Book3S PR: make mtspr/mfspr emulation behavior based on active TM SPRs

[Paul Mackerras <paulus@ozlabs.org>]

On Wed, Feb 28, 2018 at 01:52:25AM +0800, wei.guo.simon@gmail.com wrote:
> From: Simon Guo <wei.guo.simon@gmail.com>
> 
> The mfspr/mtspr on TM SPRs(TEXASR/TFIAR/TFHAR) are non-privileged
> instructions and can be executed at PR KVM guest without trapping
> into host in problem state. We only emulate mtspr/mfspr
> texasr/tfiar/tfhar at guest PR=0 state.
> 
> When we are emulating mtspr tm sprs at guest PR=0 state, the emulation
> result need to be visible to guest PR=1 state. That is, the actual TM
> SPR val should be loaded into actual registers.
> 
> We already flush TM SPRs into vcpu when switching out of CPU, and load
> TM SPRs when switching back.
> 
> This patch corrects mfspr()/mtspr() emulation for TM SPRs to make the
> actual source/dest based on actual TM SPRs.
> 
> Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
> ---
>  arch/powerpc/include/asm/kvm_book3s.h |  1 +
>  arch/powerpc/kvm/book3s_emulate.c     | 54 ++++++++++++++++++++++++++++-------
>  arch/powerpc/kvm/book3s_pr.c          |  2 +-
>  3 files changed, 46 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
> index 5911c3b..2ecb6a3 100644
> --- a/arch/powerpc/include/asm/kvm_book3s.h
> +++ b/arch/powerpc/include/asm/kvm_book3s.h
> @@ -208,6 +208,7 @@ extern long kvmppc_hv_get_dirty_log_radix(struct kvm *kvm,
>  extern void kvmppc_book3s_dequeue_irqprio(struct kvm_vcpu *vcpu,
>  					  unsigned int vec);
>  extern void kvmppc_inject_interrupt(struct kvm_vcpu *vcpu, int vec, u64 flags);
> +extern void kvmppc_trigger_fac_interrupt(struct kvm_vcpu *vcpu, ulong fac);
>  extern void kvmppc_set_bat(struct kvm_vcpu *vcpu, struct kvmppc_bat *bat,
>  			   bool upper, u32 val);
>  extern void kvmppc_giveup_ext(struct kvm_vcpu *vcpu, ulong msr);
> diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
> index 63af17f..a03533d 100644
> --- a/arch/powerpc/kvm/book3s_emulate.c
> +++ b/arch/powerpc/kvm/book3s_emulate.c
> @@ -523,13 +523,35 @@ int kvmppc_core_emulate_mtspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
>  		break;
>  #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
>  	case SPRN_TFHAR:
> -		vcpu->arch.tfhar = spr_val;
> -		break;
>  	case SPRN_TEXASR:
> -		vcpu->arch.texasr = spr_val;
> -		break;
>  	case SPRN_TFIAR:
> -		vcpu->arch.tfiar = spr_val;
> +		if (!cpu_has_feature(CPU_FTR_TM))
> +			break;
> +
> +		if (!(kvmppc_get_msr(vcpu) & MSR_TM)) {
> +			kvmppc_trigger_fac_interrupt(vcpu, FSCR_TM_LG);
> +			emulated = EMULATE_AGAIN;
> +			break;
> +		}
> +
> +		if (MSR_TM_ACTIVE(kvmppc_get_msr(vcpu))) {
> +			/* it is illegal to mtspr() TM regs in
> +			 * other than non-transactional state.
> +			 */
> +			kvmppc_core_queue_program(vcpu, SRR1_PROGTM);
> +			emulated = EMULATE_AGAIN;

According to the architecture, mtspr to TFHAR is permitted in
suspended state.

Paul.