cputlb: Move NOTDIRTY handling from I/O path to TLB path

Pages that we want to track for NOTDIRTY are RAM.  We do not
really need to go through the I/O path to handle them.

Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

accel/tcg/cputlb.c

@@ -905,7 +905,7 @@ static uint64_t io_readx(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
     mr = section->mr;
     mr_offset = (iotlbentry->addr & TARGET_PAGE_MASK) + addr;
     cpu->mem_io_pc = retaddr;
-    if (mr != &io_mem_notdirty && !cpu->can_do_io) {
+    if (!cpu->can_do_io) {
         cpu_io_recompile(cpu, retaddr);
     }
 
@@ -946,7 +946,7 @@ static void io_writex(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
     section = iotlb_to_section(cpu, iotlbentry->addr, iotlbentry->attrs);
     mr = section->mr;
     mr_offset = (iotlbentry->addr & TARGET_PAGE_MASK) + addr;
-    if (mr != &io_mem_notdirty && !cpu->can_do_io) {
+    if (!cpu->can_do_io) {
         cpu_io_recompile(cpu, retaddr);
     }
     cpu->mem_io_vaddr = addr;
@@ -1612,7 +1612,7 @@ store_helper(CPUArchState *env, target_ulong addr, uint64_t val,
         need_swap = size > 1 && (tlb_addr & TLB_BSWAP);
 
         /* Handle I/O access.  */
-        if (likely(tlb_addr & (TLB_MMIO | TLB_NOTDIRTY))) {
+        if (tlb_addr & TLB_MMIO) {
             io_writex(env, iotlbentry, mmu_idx, val, addr, retaddr,
                       op ^ (need_swap * MO_BSWAP));
             return;
@@ -1625,6 +1625,26 @@ store_helper(CPUArchState *env, target_ulong addr, uint64_t val,
 
         haddr = (void *)((uintptr_t)addr + entry->addend);
 
+        /* Handle clean RAM pages.  */
+        if (tlb_addr & TLB_NOTDIRTY) {
+            NotDirtyInfo ndi;
+
+            /* We require mem_io_pc in tb_invalidate_phys_page_range.  */
+            env_cpu(env)->mem_io_pc = retaddr;
+
+            memory_notdirty_write_prepare(&ndi, env_cpu(env), addr,
+                                          addr + iotlbentry->addr, size);
+
+            if (unlikely(need_swap)) {
+                store_memop(haddr, val, op ^ MO_BSWAP);
+            } else {
+                store_memop(haddr, val, op);
+            }
+
+            memory_notdirty_write_complete(&ndi);
+            return;
+        }
+
         /*
          * Keep these two store_memop separate to ensure that the compiler
          * is able to fold the entire function to a single instruction.

exec.c

@@ -88,7 +88,6 @@ static MemoryRegion *system_io;
 AddressSpace address_space_io;
 AddressSpace address_space_memory;
 
-MemoryRegion io_mem_notdirty;
 static MemoryRegion io_mem_unassigned;
 #endif
 
@@ -191,7 +190,6 @@ typedef struct subpage_t {
 } subpage_t;
 
 #define PHYS_SECTION_UNASSIGNED 0
-#define PHYS_SECTION_NOTDIRTY 1
 
 static void io_mem_init(void);
 static void memory_map_init(void);
@@ -1472,9 +1470,6 @@ hwaddr memory_region_section_get_iotlb(CPUState *cpu,
     if (memory_region_is_ram(section->mr)) {
         /* Normal RAM.  */
         iotlb = memory_region_get_ram_addr(section->mr) + xlat;
-        if (!section->readonly) {
-            iotlb |= PHYS_SECTION_NOTDIRTY;
-        }
     } else {
         AddressSpaceDispatch *d;
 
@@ -2783,42 +2778,6 @@ void memory_notdirty_write_complete(NotDirtyInfo *ndi)
     }
 }
 
-/* Called within RCU critical section.  */
-static void notdirty_mem_write(void *opaque, hwaddr ram_addr,
-                               uint64_t val, unsigned size)
-{
-    NotDirtyInfo ndi;
-
-    memory_notdirty_write_prepare(&ndi, current_cpu, current_cpu->mem_io_vaddr,
-                         ram_addr, size);
-
-    stn_p(qemu_map_ram_ptr(NULL, ram_addr), size, val);
-    memory_notdirty_write_complete(&ndi);
-}
-
-static bool notdirty_mem_accepts(void *opaque, hwaddr addr,
-                                 unsigned size, bool is_write,
-                                 MemTxAttrs attrs)
-{
-    return is_write;
-}
-
-static const MemoryRegionOps notdirty_mem_ops = {
-    .write = notdirty_mem_write,
-    .valid.accepts = notdirty_mem_accepts,
-    .endianness = DEVICE_NATIVE_ENDIAN,
-    .valid = {
-        .min_access_size = 1,
-        .max_access_size = 8,
-        .unaligned = false,
-    },
-    .impl = {
-        .min_access_size = 1,
-        .max_access_size = 8,
-        .unaligned = false,
-    },
-};
-
 /* Generate a debug exception if a watchpoint has been hit.  */
 void cpu_check_watchpoint(CPUState *cpu, vaddr addr, vaddr len,
                           MemTxAttrs attrs, int flags, uintptr_t ra)
@@ -3014,13 +2973,6 @@ static void io_mem_init(void)
 {
     memory_region_init_io(&io_mem_unassigned, NULL, &unassigned_mem_ops, NULL,
                           NULL, UINT64_MAX);
-
-    /* io_mem_notdirty calls tb_invalidate_phys_page_fast,
-     * which can be called without the iothread mutex.
-     */
-    memory_region_init_io(&io_mem_notdirty, NULL, &notdirty_mem_ops, NULL,
-                          NULL, UINT64_MAX);
-    memory_region_clear_global_locking(&io_mem_notdirty);
 }
 
 AddressSpaceDispatch *address_space_dispatch_new(FlatView *fv)
@@ -3030,8 +2982,6 @@ AddressSpaceDispatch *address_space_dispatch_new(FlatView *fv)
 
     n = dummy_section(&d->map, fv, &io_mem_unassigned);
     assert(n == PHYS_SECTION_UNASSIGNED);
-    n = dummy_section(&d->map, fv, &io_mem_notdirty);
-    assert(n == PHYS_SECTION_NOTDIRTY);
 
     d->phys_map  = (PhysPageEntry) { .ptr = PHYS_MAP_NODE_NIL, .skip = 1 };
 

include/exec/cpu-common.h

@@ -100,8 +100,6 @@ void qemu_flush_coalesced_mmio_buffer(void);
 
 void cpu_flush_icache_range(hwaddr start, hwaddr len);
 
-extern struct MemoryRegion io_mem_notdirty;
-
 typedef int (RAMBlockIterFunc)(RAMBlock *rb, void *opaque);
 
 int qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque);

memory.c

@@ -434,10 +434,6 @@ static MemTxResult  memory_region_read_accessor(MemoryRegion *mr,
     tmp = mr->ops->read(mr->opaque, addr, size);
     if (mr->subpage) {
         trace_memory_region_subpage_read(get_cpu_index(), mr, addr, tmp, size);
-    } else if (mr == &io_mem_notdirty) {
-        /* Accesses to code which has previously been translated into a TB show
-         * up in the MMIO path, as accesses to the io_mem_notdirty
-         * MemoryRegion. */
     } else if (TRACE_MEMORY_REGION_OPS_READ_ENABLED) {
         hwaddr abs_addr = memory_region_to_absolute_addr(mr, addr);
         trace_memory_region_ops_read(get_cpu_index(), mr, abs_addr, tmp, size);
@@ -460,10 +456,6 @@ static MemTxResult memory_region_read_with_attrs_accessor(MemoryRegion *mr,
     r = mr->ops->read_with_attrs(mr->opaque, addr, &tmp, size, attrs);
     if (mr->subpage) {
         trace_memory_region_subpage_read(get_cpu_index(), mr, addr, tmp, size);
-    } else if (mr == &io_mem_notdirty) {
-        /* Accesses to code which has previously been translated into a TB show
-         * up in the MMIO path, as accesses to the io_mem_notdirty
-         * MemoryRegion. */
     } else if (TRACE_MEMORY_REGION_OPS_READ_ENABLED) {
         hwaddr abs_addr = memory_region_to_absolute_addr(mr, addr);
         trace_memory_region_ops_read(get_cpu_index(), mr, abs_addr, tmp, size);
@@ -484,10 +476,6 @@ static MemTxResult memory_region_write_accessor(MemoryRegion *mr,
 
     if (mr->subpage) {
         trace_memory_region_subpage_write(get_cpu_index(), mr, addr, tmp, size);
-    } else if (mr == &io_mem_notdirty) {
-        /* Accesses to code which has previously been translated into a TB show
-         * up in the MMIO path, as accesses to the io_mem_notdirty
-         * MemoryRegion. */
     } else if (TRACE_MEMORY_REGION_OPS_WRITE_ENABLED) {
         hwaddr abs_addr = memory_region_to_absolute_addr(mr, addr);
         trace_memory_region_ops_write(get_cpu_index(), mr, abs_addr, tmp, size);
@@ -508,10 +496,6 @@ static MemTxResult memory_region_write_with_attrs_accessor(MemoryRegion *mr,
 
     if (mr->subpage) {
         trace_memory_region_subpage_write(get_cpu_index(), mr, addr, tmp, size);
-    } else if (mr == &io_mem_notdirty) {
-        /* Accesses to code which has previously been translated into a TB show
-         * up in the MMIO path, as accesses to the io_mem_notdirty
-         * MemoryRegion. */
     } else if (TRACE_MEMORY_REGION_OPS_WRITE_ENABLED) {
         hwaddr abs_addr = memory_region_to_absolute_addr(mr, addr);
         trace_memory_region_ops_write(get_cpu_index(), mr, abs_addr, tmp, size);