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

["Cédric Le Goater" <clg@kaod.org>]

On 06/14/2016 08:34 AM, David Gibson wrote:
> 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?

No. I forgot to add this patch from Andrei :

	https://github.com/legoater/qemu/commit/e218fd3ba945bb0f483f5f12bedbb74d897cd5b9

I will send it as a fix.

C.  

>> +        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;
>>      }
>