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Re: [PATCH v7 10/17] target/ppc: Only calculate RMLS derived RMA limit o


From: Philippe Mathieu-Daudé
Subject: Re: [PATCH v7 10/17] target/ppc: Only calculate RMLS derived RMA limit on demand
Date: Thu, 5 Mar 2020 09:48:29 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1

On 3/3/20 4:43 AM, David Gibson wrote:
When the LPCR is written, we update the env->rmls field with the RMA limit
it implies.  Simplify things by just calculating the value directly from
the LPCR value when we need it.

It's possible this is a little slower, but it's unlikely to be significant,
since this is only for real mode accesses in a translation configuration
that's not used very often, and the whole thing is behind the qemu TLB
anyway.  Therefore, keeping the number of state variables down and not
having to worry about making sure it's always in sync seems the better
option.

Signed-off-by: David Gibson <address@hidden>
---
  target/ppc/cpu.h        | 1 -
  target/ppc/mmu-hash64.c | 9 ++++++---
  2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
index 8077fdb068..f9871b1233 100644
--- a/target/ppc/cpu.h
+++ b/target/ppc/cpu.h
@@ -1046,7 +1046,6 @@ struct CPUPPCState {
      uint64_t insns_flags2;
  #if defined(TARGET_PPC64)
      ppc_slb_t vrma_slb;
-    target_ulong rmls;
  #endif
int error_code;
diff --git a/target/ppc/mmu-hash64.c b/target/ppc/mmu-hash64.c
index fcccaabb88..4fd7b7ee74 100644
--- a/target/ppc/mmu-hash64.c
+++ b/target/ppc/mmu-hash64.c
@@ -837,8 +837,10 @@ int ppc_hash64_handle_mmu_fault(PowerPCCPU *cpu, vaddr 
eaddr,
goto skip_slb_search;
          } else {
+            target_ulong limit = rmls_limit(cpu);
+
              /* Emulated old-style RMO mode, bounds check against RMLS */
-            if (raddr >= env->rmls) {
+            if (raddr >= limit) {
                  if (rwx == 2) {
                      ppc_hash64_set_isi(cs, SRR1_PROTFAULT);
                  } else {
@@ -1000,8 +1002,10 @@ hwaddr ppc_hash64_get_phys_page_debug(PowerPCCPU *cpu, 
target_ulong addr)
                  return -1;
              }
          } else {
+            target_ulong limit = rmls_limit(cpu);
+
              /* Emulated old-style RMO mode, bounds check against RMLS */
-            if (raddr >= env->rmls) {
+            if (raddr >= limit) {
                  return -1;
              }
              return raddr | env->spr[SPR_RMOR];
@@ -1091,7 +1095,6 @@ void ppc_store_lpcr(PowerPCCPU *cpu, target_ulong val)
      CPUPPCState *env = &cpu->env;
env->spr[SPR_LPCR] = val & pcc->lpcr_mask;
-    env->rmls = rmls_limit(cpu);
      ppc_hash64_update_vrma(cpu);
  }

Reviewed-by: Philippe Mathieu-Daudé <address@hidden>




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