Re: [Qemu-devel] [PATCH 2/2] ppc: Fix 64K pages support in full emulation

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

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On Tue, Jun 28, 2016 at 08:48:34AM +0200, Cédric Le Goater wrote:
> From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> 
> We were always advertising only 4K & 16M. Additionally the code wasn't
> properly matching the page size with the PTE content, which meant we
> could potentially hit an incorrect PTE if the guest used multiple sizes.
> 
> Finally, honor the CPU capabilities when decoding the size from the SLB
> so we don't try to use 64K pages on 970.
> 
> This still doesn't add support for MPSS (Multiple Page Sizes per Segment)
> 
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> [clg: fixed checkpatch.pl errors
>       commits 61a36c9b5a12 and 1114e712c998 reworked the hpte code
>       doing insertion/removal in hw/ppc/spapr_hcall.c. The hunks
>       modifying these areas were removed. ]
> Signed-off-by: Cédric Le Goater <clg@kaod.org>

Applied to ppc-for-2.7.

> ---
>  target-ppc/cpu-qom.h        |  3 +++
>  target-ppc/mmu-hash64.c     | 39 +++++++++++++++++++++++++++++++++++----
>  target-ppc/translate_init.c | 22 +++++++++++++++++++---
>  3 files changed, 57 insertions(+), 7 deletions(-)
> 
> diff --git a/target-ppc/cpu-qom.h b/target-ppc/cpu-qom.h
> index 0fad2def0a94..286410502f6d 100644
> --- a/target-ppc/cpu-qom.h
> +++ b/target-ppc/cpu-qom.h
> @@ -70,18 +70,21 @@ enum powerpc_mmu_t {
>  #define POWERPC_MMU_64       0x00010000
>  #define POWERPC_MMU_1TSEG    0x00020000
>  #define POWERPC_MMU_AMR      0x00040000
> +#define POWERPC_MMU_64K      0x00080000
>      /* 64 bits PowerPC MMU                                     */
>      POWERPC_MMU_64B        = POWERPC_MMU_64 | 0x00000001,
>      /* Architecture 2.03 and later (has LPCR) */
>      POWERPC_MMU_2_03       = POWERPC_MMU_64 | 0x00000002,
>      /* Architecture 2.06 variant                               */
>      POWERPC_MMU_2_06       = POWERPC_MMU_64 | POWERPC_MMU_1TSEG
> +                             | POWERPC_MMU_64K
>                               | POWERPC_MMU_AMR | 0x00000003,
>      /* Architecture 2.06 "degraded" (no 1T segments)           */
>      POWERPC_MMU_2_06a      = POWERPC_MMU_64 | POWERPC_MMU_AMR
>                               | 0x00000003,
>      /* Architecture 2.07 variant                               */
>      POWERPC_MMU_2_07       = POWERPC_MMU_64 | POWERPC_MMU_1TSEG
> +                             | POWERPC_MMU_64K
>                               | POWERPC_MMU_AMR | 0x00000004,
>      /* Architecture 2.07 "degraded" (no 1T segments)           */
>      POWERPC_MMU_2_07a      = POWERPC_MMU_64 | POWERPC_MMU_AMR
> diff --git a/target-ppc/mmu-hash64.c b/target-ppc/mmu-hash64.c
> index ed353b2d1539..fa26ad2e875b 100644
> --- a/target-ppc/mmu-hash64.c
> +++ b/target-ppc/mmu-hash64.c
> @@ -450,9 +450,31 @@ void ppc_hash64_stop_access(PowerPCCPU *cpu, uint64_t token)
>      }
>  }
>  
> +/* Returns the effective page shift or 0. MPSS isn't supported yet so
> + * this will always be the slb_pshift or 0
> + */
> +static uint32_t ppc_hash64_pte_size_decode(uint64_t pte1, uint32_t slb_pshift)
> +{
> +    switch (slb_pshift) {
> +    case 12:
> +        return 12;
> +    case 16:
> +        if ((pte1 & 0xf000) == 0x1000) {
> +            return 16;
> +        }
> +        return 0;
> +    case 24:
> +        if ((pte1 & 0xff000) == 0) {
> +            return 24;
> +        }
> +        return 0;
> +    }
> +    return 0;
> +}
> +
>  static hwaddr ppc_hash64_pteg_search(PowerPCCPU *cpu, hwaddr hash,
> -                                     bool secondary, target_ulong ptem,
> -                                     ppc_hash_pte64_t *pte)
> +                                     uint32_t slb_pshift, bool secondary,
> +                                     target_ulong ptem, ppc_hash_pte64_t *pte)
>  {
>      CPUPPCState *env = &cpu->env;
>      int i;
> @@ -472,6 +494,13 @@ static hwaddr ppc_hash64_pteg_search(PowerPCCPU *cpu, hwaddr hash,
>          if ((pte0 & HPTE64_V_VALID)
>              && (secondary == !!(pte0 & HPTE64_V_SECONDARY))
>              && HPTE64_V_COMPARE(pte0, ptem)) {
> +            uint32_t pshift = ppc_hash64_pte_size_decode(pte1, slb_pshift);
> +            if (pshift == 0) {
> +                continue;
> +            }
> +            /* We don't do anything with pshift yet as qemu TLB only deals
> +             * with 4K pages anyway
> +             */
>              pte->pte0 = pte0;
>              pte->pte1 = pte1;
>              ppc_hash64_stop_access(cpu, token);
> @@ -525,7 +554,8 @@ static hwaddr ppc_hash64_htab_lookup(PowerPCCPU *cpu,
>              " vsid=" TARGET_FMT_lx " ptem=" TARGET_FMT_lx
>              " hash=" TARGET_FMT_plx "\n",
>              env->htab_base, env->htab_mask, vsid, ptem,  hash);
> -    pte_offset = ppc_hash64_pteg_search(cpu, hash, 0, ptem, pte);
> +    pte_offset = ppc_hash64_pteg_search(cpu, hash, slb->sps->page_shift,
> +                                        0, ptem, pte);
>  
>      if (pte_offset == -1) {
>          /* Secondary PTEG lookup */
> @@ -535,7 +565,8 @@ static hwaddr ppc_hash64_htab_lookup(PowerPCCPU *cpu,
>                  " hash=" TARGET_FMT_plx "\n", env->htab_base,
>                  env->htab_mask, vsid, ptem, ~hash);
>  
> -        pte_offset = ppc_hash64_pteg_search(cpu, ~hash, 1, ptem, pte);
> +        pte_offset = ppc_hash64_pteg_search(cpu, ~hash, slb->sps->page_shift, 1,
> +                                            ptem, pte);
>      }
>  
>      return pte_offset;
> diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
> index 4820c0bc99fb..d7860fd7f8ee 100644
> --- a/target-ppc/translate_init.c
> +++ b/target-ppc/translate_init.c
> @@ -10301,8 +10301,8 @@ static void ppc_cpu_initfn(Object *obj)
>      if (pcc->sps) {
>          env->sps = *pcc->sps;
>      } else if (env->mmu_model & POWERPC_MMU_64) {
> -        /* Use default sets of page sizes */
> -        static const struct ppc_segment_page_sizes defsps = {
> +        /* Use default sets of page sizes. We don't support MPSS */
> +        static const struct ppc_segment_page_sizes defsps_4k = {
>              .sps = {
>                  { .page_shift = 12, /* 4K */
>                    .slb_enc = 0,
> @@ -10314,7 +10314,23 @@ static void ppc_cpu_initfn(Object *obj)
>                  },
>              },
>          };
> -        env->sps = defsps;
> +        static const struct ppc_segment_page_sizes defsps_64k = {
> +            .sps = {
> +                { .page_shift = 12, /* 4K */
> +                  .slb_enc = 0,
> +                  .enc = { { .page_shift = 12, .pte_enc = 0 } }
> +                },
> +                { .page_shift = 16, /* 64K */
> +                  .slb_enc = 0x110,
> +                  .enc = { { .page_shift = 16, .pte_enc = 1 } }
> +                },
> +                { .page_shift = 24, /* 16M */
> +                  .slb_enc = 0x100,
> +                  .enc = { { .page_shift = 24, .pte_enc = 0 } }
> +                },
> +            },
> +        };
> +        env->sps = (env->mmu_model & POWERPC_MMU_64K) ? defsps_64k : defsps_4k;
>      }
>  #endif /* defined(TARGET_PPC64) */
>  

-- 
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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