Re: [Qemu-devel] [PATCH 05/10] ppc: Fix generation if ISI/DSI vs. HV mode

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Jun 13, 2016 at 07:24:51AM +0200, Cédric Le Goater wrote:
> From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> 
> Under some circumstances, we need to direct ISI and DSI interrupts
> at the hypervisor, turning them into HISI/HDSI, and using different
> SPRs (HDSISR and HDAR) depending on the combination of MSR_DR and
> the corresponding VPM bits in LPCR.
> 
> This moves part of the code into helpers that are fixed to select
> the right exception type and registers. On pre-P7 processors, LPCR
> is 0 which provides the old behaviour of directing the interrupts
> at the supervisor.
> 
> Thanks to Andrei Warkentin for finding a bug when HV=1
> 
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  target-ppc/mmu-hash64.c | 69 +++++++++++++++++++++++++++++++++++--------------
>  1 file changed, 50 insertions(+), 19 deletions(-)
> 
> diff --git a/target-ppc/mmu-hash64.c b/target-ppc/mmu-hash64.c
> index 668da5e22653..072a952c8bd5 100644
> --- a/target-ppc/mmu-hash64.c
> +++ b/target-ppc/mmu-hash64.c
> @@ -613,6 +613,47 @@ unsigned ppc_hash64_hpte_page_shift_noslb(PowerPCCPU *cpu,
>      return 0;
>  }
>  
> +static void ppc_hash64_set_isi(CPUState *cs, CPUPPCState *env,
> +                               uint64_t error_code)
> +{
> +    bool vpm;
> +
> +    if (msr_ir) {
> +        vpm = !!(env->spr[SPR_LPCR] & LPCR_VPM1);
> +    } else {
> +        vpm = !!(env->spr[SPR_LPCR] & LPCR_VPM0);
> +    }
> +    if (vpm && !msr_hv) {
> +        cs->exception_index = POWERPC_EXCP_HISI;

In the ISI case, you use HISI if !msr_hv..

> +    } else {
> +        cs->exception_index = POWERPC_EXCP_ISI;
> +    }
> +    env->error_code = error_code;
> +}
> +
> +static void ppc_hash64_set_dsi(CPUState *cs, CPUPPCState *env, uint64_t dar,
> +                               uint64_t dsisr)
> +{
> +    bool vpm;
> +
> +    if (msr_dr) {
> +        vpm = !!(env->spr[SPR_LPCR] & LPCR_VPM1);
> +    } else {
> +        vpm = !!(env->spr[SPR_LPCR] & LPCR_VPM0);
> +    }
> +    if (vpm && msr_hv) {
> +        cs->exception_index = POWERPC_EXCP_HDSI;

..but in the DSI case you use HDSI if msr_hv.  Is that really right?

> +        env->spr[SPR_HDAR] = dar;
> +        env->spr[SPR_HDSISR] = dsisr;
> +    } else {
> +        cs->exception_index = POWERPC_EXCP_DSI;
> +        env->spr[SPR_DAR] = dar;
> +        env->spr[SPR_DSISR] = dsisr;
> +   }
> +    env->error_code = 0;
> +}
> +
> +
>  int ppc_hash64_handle_mmu_fault(PowerPCCPU *cpu, vaddr eaddr,
>                                  int rwx, int mmu_idx)
>  {
> @@ -623,7 +664,7 @@ int ppc_hash64_handle_mmu_fault(PowerPCCPU *cpu, vaddr eaddr,
>      hwaddr pte_offset;
>      ppc_hash_pte64_t pte;
>      int pp_prot, amr_prot, prot;
> -    uint64_t new_pte1;
> +    uint64_t new_pte1, dsisr;
>      const int need_prot[] = {PAGE_READ, PAGE_WRITE, PAGE_EXEC};
>      hwaddr raddr;
>  
> @@ -657,26 +698,21 @@ int ppc_hash64_handle_mmu_fault(PowerPCCPU *cpu, vaddr eaddr,
>  
>      /* 3. Check for segment level no-execute violation */
>      if ((rwx == 2) && (slb->vsid & SLB_VSID_N)) {
> -        cs->exception_index = POWERPC_EXCP_ISI;
> -        env->error_code = 0x10000000;
> +        ppc_hash64_set_isi(cs, env, 0x10000000);
>          return 1;
>      }
>  
>      /* 4. Locate the PTE in the hash table */
>      pte_offset = ppc_hash64_htab_lookup(cpu, slb, eaddr, &pte);
>      if (pte_offset == -1) {
> +        dsisr = 0x40000000;
>          if (rwx == 2) {
> -            cs->exception_index = POWERPC_EXCP_ISI;
> -            env->error_code = 0x40000000;
> +            ppc_hash64_set_isi(cs, env, dsisr);
>          } else {
> -            cs->exception_index = POWERPC_EXCP_DSI;
> -            env->error_code = 0;
> -            env->spr[SPR_DAR] = eaddr;
>              if (rwx == 1) {
> -                env->spr[SPR_DSISR] = 0x42000000;
> -            } else {
> -                env->spr[SPR_DSISR] = 0x40000000;
> +                dsisr |= 0x02000000;
>              }
> +            ppc_hash64_set_dsi(cs, env, eaddr, dsisr);
>          }
>          return 1;
>      }
> @@ -705,14 +741,9 @@ int ppc_hash64_handle_mmu_fault(PowerPCCPU *cpu, vaddr eaddr,
>          /* Access right violation */
>          qemu_log_mask(CPU_LOG_MMU, "PTE access rejected\n");
>          if (rwx == 2) {
> -            cs->exception_index = POWERPC_EXCP_ISI;
> -            env->error_code = 0x08000000;
> +            ppc_hash64_set_isi(cs, env, 0x08000000);
>          } else {
> -            target_ulong dsisr = 0;
> -
> -            cs->exception_index = POWERPC_EXCP_DSI;
> -            env->error_code = 0;
> -            env->spr[SPR_DAR] = eaddr;
> +            dsisr = 0;
>              if (need_prot[rwx] & ~pp_prot) {
>                  dsisr |= 0x08000000;
>              }
> @@ -722,7 +753,7 @@ int ppc_hash64_handle_mmu_fault(PowerPCCPU *cpu, vaddr eaddr,
>              if (need_prot[rwx] & ~amr_prot) {
>                  dsisr |= 0x00200000;
>              }
> -            env->spr[SPR_DSISR] = dsisr;
> +            ppc_hash64_set_dsi(cs, env, eaddr, dsisr);
>          }
>          return 1;
>      }

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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