[Qemu-devel] [RFC] support more than 2 execution modes

[Qemu-devel] [RFC] support more than 2 execution modes

[J. Mayer]

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It appears that some targets may need more than the 2 "standard"
execution modes.
For example, PowerPC 64 has 3 execution modes: hypervisor, supervisor
and problem state.
Another example is alpha which has 4 execution modes (even if Linux
seems to use only two of them).

My proposal is to increase the number of the tlb_tables entries in a way
that would be selected at compile time in order to keep good
performances for other emulated targets that do not need this feature.

You'll find attached a short patch implementing it. With this patch, one
would just have to properly define CPU_MEM_INDEX and is_user flags for
those targets.

Please comment.

-- 
J. Mayer <l_indien@magic.fr>
Never organized


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Index: cpu-defs.h
===================================================================
RCS file: /sources/qemu/qemu/cpu-defs.h,v
retrieving revision 1.18
diff -u -d -d -p -r1.18 cpu-defs.h
--- cpu-defs.h	16 Mar 2007 23:58:11 -0000	1.18
+++ cpu-defs.h	26 Mar 2007 06:52:11 -0000
@@ -106,6 +108,13 @@ typedef struct CPUTLBEntry {
     target_phys_addr_t addend; 
 } CPUTLBEntry;
 
+/* Alpha has 4 different running levels */
+#if defined(TARGET_ALPHA)
+#define NB_MMU_MODES 4
+#else
+#define NB_MMU_MODES 2
+#endif
+
 #define CPU_COMMON                                                      \
     struct TranslationBlock *current_tb; /* currently executing TB  */  \
     /* soft mmu support */                                              \
@@ -117,7 +126,7 @@ typedef struct CPUTLBEntry {
     target_ulong mem_write_vaddr; /* target virtual addr at which the   \
                                      memory was written */              \
     /* 0 = kernel, 1 = user */                                          \
-    CPUTLBEntry tlb_table[2][CPU_TLB_SIZE];                             \
+    CPUTLBEntry tlb_table[NB_MMU_MODES][CPU_TLB_SIZE];                  \
     struct TranslationBlock *tb_jmp_cache[TB_JMP_CACHE_SIZE];           \
                                                                         \
     /* from this point: preserved by CPU reset */                       \
Index: exec.c
===================================================================
RCS file: /sources/qemu/qemu/exec.c,v
retrieving revision 1.89
diff -u -d -d -p -r1.89 exec.c
--- exec.c	17 Mar 2007 15:17:58 -0000	1.89
+++ exec.c	26 Mar 2007 06:52:11 -0000
@@ -1300,6 +1307,16 @@ void tlb_flush(CPUState *env, int flush_
         env->tlb_table[1][i].addr_read = -1;
         env->tlb_table[1][i].addr_write = -1;
         env->tlb_table[1][i].addr_code = -1;
+#if (NB_MMU_MODES >= 3)
+        env->tlb_table[2][i].addr_read = -1;
+        env->tlb_table[2][i].addr_write = -1;
+        env->tlb_table[2][i].addr_code = -1;
+#if (NB_MMU_MODES == 4)
+        env->tlb_table[3][i].addr_read = -1;
+        env->tlb_table[3][i].addr_write = -1;
+        env->tlb_table[3][i].addr_code = -1;
+#endif
+#endif
     }
 
     memset (env->tb_jmp_cache, 0, TB_JMP_CACHE_SIZE * sizeof (void *));
@@ -1345,6 +1362,12 @@ void tlb_flush_page(CPUState *env, targe
     i = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
     tlb_flush_entry(&env->tlb_table[0][i], addr);
     tlb_flush_entry(&env->tlb_table[1][i], addr);
+#if (NB_MMU_MODES >= 3)
+    tlb_flush_entry(&env->tlb_table[2][i], addr);
+#if (NB_MMU_MODES == 4)
+    tlb_flush_entry(&env->tlb_table[3][i], addr);
+#endif
+#endif
 
     /* Discard jump cache entries for any tb which might potentially
        overlap the flushed page.  */
@@ -1434,6 +1457,14 @@ void cpu_physical_memory_reset_dirty(ram
             tlb_reset_dirty_range(&env->tlb_table[0][i], start1, length);
         for(i = 0; i < CPU_TLB_SIZE; i++)
             tlb_reset_dirty_range(&env->tlb_table[1][i], start1, length);
+#if (NB_MMU_MODES >= 3)
+        for(i = 0; i < CPU_TLB_SIZE; i++)
+            tlb_reset_dirty_range(&env->tlb_table[2][i], start1, length);
+#if (NB_MMU_MODES == 4)
+        for(i = 0; i < CPU_TLB_SIZE; i++)
+            tlb_reset_dirty_range(&env->tlb_table[3][i], start1, length);
+#endif
+#endif
     }
 
 #if !defined(CONFIG_SOFTMMU)
@@ -1486,6 +1517,14 @@ void cpu_tlb_update_dirty(CPUState *env)
         tlb_update_dirty(&env->tlb_table[0][i]);
     for(i = 0; i < CPU_TLB_SIZE; i++)
         tlb_update_dirty(&env->tlb_table[1][i]);
+#if (NB_MMU_MODES >= 3)
+    for(i = 0; i < CPU_TLB_SIZE; i++)
+        tlb_update_dirty(&env->tlb_table[2][i]);
+#if (NB_MMU_MODES == 4)
+    for(i = 0; i < CPU_TLB_SIZE; i++)
+        tlb_update_dirty(&env->tlb_table[3][i]);
+#endif
+#endif
 }
 
 static inline void tlb_set_dirty1(CPUTLBEntry *tlb_entry, 
@@ -1511,6 +1550,12 @@ static inline void tlb_set_dirty(CPUStat
     i = (vaddr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
     tlb_set_dirty1(&env->tlb_table[0][i], addr);
     tlb_set_dirty1(&env->tlb_table[1][i], addr);
+#if (NB_MMU_MODES >= 3)
+    tlb_set_dirty1(&env->tlb_table[2][i], addr);
+#if (NB_MMU_MODES == 4)
+    tlb_set_dirty1(&env->tlb_table[3][i], addr);
+#endif
+#endif
 }
 
 /* add a new TLB entry. At most one entry for a given virtual address

Re: [Qemu-devel] [RFC] support more than 2 execution modes

[Thiemo Seufer]

J. Mayer wrote:
> It appears that some targets may need more than the 2 "standard"
> execution modes.
> For example, PowerPC 64 has 3 execution modes: hypervisor, supervisor
> and problem state.
> Another example is alpha which has 4 execution modes (even if Linux
> seems to use only two of them).
> 
> My proposal is to increase the number of the tlb_tables entries in a way
> that would be selected at compile time in order to keep good
> performances for other emulated targets that do not need this feature.
> 
> You'll find attached a short patch implementing it. With this patch, one
> would just have to properly define CPU_MEM_INDEX and is_user flags for
> those targets.
> 
> Please comment.

Looks good to me, as it will help to implement MIPS supervisor mode
some day. :-)


Thiemo