memory: split memory_region_from_host from qemu_ram_addr_from_host

Move the old qemu_ram_addr_from_host to memory_region_from_host and
make it return an offset within the region.  For qemu_ram_addr_from_host
return the ram_addr_t directly, similar to what it was before
commit 1b5ec23 ("memory: return MemoryRegion from qemu_ram_addr_from_host",
2013-07-04).

Reviewed-by: Marc-André Lureau <marcandre.lureau@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

cputlb.c

@@ -246,7 +246,8 @@ static inline ram_addr_t qemu_ram_addr_from_host_nofail(void *ptr)
 {
     ram_addr_t ram_addr;
 
-    if (qemu_ram_addr_from_host(ptr, &ram_addr) == NULL) {
+    ram_addr = qemu_ram_addr_from_host(ptr);
+    if (ram_addr == RAM_ADDR_INVALID) {
         fprintf(stderr, "Bad ram pointer %p\n", ptr);
         abort();
     }

exec.c

@@ -1964,18 +1964,17 @@ RAMBlock *qemu_ram_block_by_name(const char *name)
 
 /* Some of the softmmu routines need to translate from a host pointer
    (typically a TLB entry) back to a ram offset.  */
-MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr)
+ram_addr_t qemu_ram_addr_from_host(void *ptr)
 {
     RAMBlock *block;
     ram_addr_t offset;
 
     block = qemu_ram_block_from_host(ptr, false, &offset);
-    *ram_addr = block->offset + offset;
     if (!block) {
-        return NULL;
+        return RAM_ADDR_INVALID;
     }
 
-    return block->mr;
+    return block->offset + offset;
 }
 
 /* Called within RCU critical section.  */
@@ -2975,8 +2974,9 @@ void address_space_unmap(AddressSpace *as, void *buffer, hwaddr len,
         MemoryRegion *mr;
         ram_addr_t addr1;
 
-        mr = qemu_ram_addr_from_host(buffer, &addr1);
+        mr = memory_region_from_host(buffer, &addr1);
         assert(mr != NULL);
+        addr1 += memory_region_get_ram_addr(mr);
         if (is_write) {
             invalidate_and_set_dirty(mr, addr1, access_len);
         }

hw/virtio/vhost-user.c

@@ -17,7 +17,6 @@
 #include "sysemu/kvm.h"
 #include "qemu/error-report.h"
 #include "qemu/sockets.h"
-#include "exec/ram_addr.h"
 #include "migration/migration.h"
 
 #include <sys/ioctl.h>
@@ -247,19 +246,18 @@ static int vhost_user_set_mem_table(struct vhost_dev *dev,
 
     for (i = 0; i < dev->mem->nregions; ++i) {
         struct vhost_memory_region *reg = dev->mem->regions + i;
-        ram_addr_t ram_addr;
+        ram_addr_t offset;
         MemoryRegion *mr;
 
         assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
-        mr = qemu_ram_addr_from_host((void *)(uintptr_t)reg->userspace_addr,
-                                     &ram_addr);
+        mr = memory_region_from_host((void *)(uintptr_t)reg->userspace_addr,
+                                     &offset);
         fd = memory_region_get_fd(mr);
         if (fd > 0) {
             msg.payload.memory.regions[fd_num].userspace_addr = reg->userspace_addr;
             msg.payload.memory.regions[fd_num].memory_size  = reg->memory_size;
             msg.payload.memory.regions[fd_num].guest_phys_addr = reg->guest_phys_addr;
-            msg.payload.memory.regions[fd_num].mmap_offset = reg->userspace_addr -
-                (uintptr_t) memory_region_get_ram_ptr(mr);
+            msg.payload.memory.regions[fd_num].mmap_offset = offset;
             assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
             fds[fd_num++] = fd;
         }
@@ -617,14 +615,14 @@ static bool vhost_user_can_merge(struct vhost_dev *dev,
                                  uint64_t start1, uint64_t size1,
                                  uint64_t start2, uint64_t size2)
 {
-    ram_addr_t ram_addr;
+    ram_addr_t offset;
     int mfd, rfd;
     MemoryRegion *mr;
 
-    mr = qemu_ram_addr_from_host((void *)(uintptr_t)start1, &ram_addr);
+    mr = memory_region_from_host((void *)(uintptr_t)start1, &offset);
     mfd = memory_region_get_fd(mr);
 
-    mr = qemu_ram_addr_from_host((void *)(uintptr_t)start2, &ram_addr);
+    mr = memory_region_from_host((void *)(uintptr_t)start2, &offset);
     rfd = memory_region_get_fd(mr);
 
     return mfd == rfd;

include/exec/cpu-common.h

@@ -57,7 +57,7 @@ typedef uint32_t CPUReadMemoryFunc(void *opaque, hwaddr addr);
 
 void qemu_ram_remap(ram_addr_t addr, ram_addr_t length);
 /* This should not be used by devices.  */
-MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr);
+ram_addr_t qemu_ram_addr_from_host(void *ptr);
 RAMBlock *qemu_ram_block_by_name(const char *name);
 RAMBlock *qemu_ram_block_from_host(void *ptr, bool round_offset,
                                    ram_addr_t *offset);

include/exec/memory.h

@@ -32,6 +32,8 @@
 #include "qom/object.h"
 #include "qemu/rcu.h"
 
+#define RAM_ADDR_INVALID (~(ram_addr_t)0)
+
 #define MAX_PHYS_ADDR_SPACE_BITS 62
 #define MAX_PHYS_ADDR            (((hwaddr)1 << MAX_PHYS_ADDR_SPACE_BITS) - 1)
 
@@ -677,6 +679,24 @@ int memory_region_get_fd(MemoryRegion *mr);
  */
 void memory_region_set_fd(MemoryRegion *mr, int fd);
 
+/**
+ * memory_region_from_host: Convert a pointer into a RAM memory region
+ * and an offset within it.
+ *
+ * Given a host pointer inside a RAM memory region (created with
+ * memory_region_init_ram() or memory_region_init_ram_ptr()), return
+ * the MemoryRegion and the offset within it.
+ *
+ * Use with care; by the time this function returns, the returned pointer is
+ * not protected by RCU anymore.  If the caller is not within an RCU critical
+ * section and does not hold the iothread lock, it must have other means of
+ * protecting the pointer, such as a reference to the region that includes
+ * the incoming ram_addr_t.
+ *
+ * @mr: the memory region being queried.
+ */
+MemoryRegion *memory_region_from_host(void *ptr, ram_addr_t *offset);
+
 /**
  * memory_region_get_ram_ptr: Get a pointer into a RAM memory region.
  *

memory.c

@@ -33,8 +33,6 @@
 
 //#define DEBUG_UNASSIGNED
 
-#define RAM_ADDR_INVALID (~(ram_addr_t)0)
-
 static unsigned memory_region_transaction_depth;
 static bool memory_region_update_pending;
 static bool ioeventfd_update_pending;
@@ -1665,6 +1663,18 @@ void *memory_region_get_ram_ptr(MemoryRegion *mr)
     return ptr + offset;
 }
 
+MemoryRegion *memory_region_from_host(void *ptr, ram_addr_t *offset)
+{
+    RAMBlock *block;
+
+    block = qemu_ram_block_from_host(ptr, false, offset);
+    if (!block) {
+        return NULL;
+    }
+
+    return block->mr;
+}
+
 ram_addr_t memory_region_get_ram_addr(MemoryRegion *mr)
 {
     return mr->ram_block ? mr->ram_block->offset : RAM_ADDR_INVALID;

target-i386/kvm.c

@@ -411,7 +411,8 @@ int kvm_arch_on_sigbus_vcpu(CPUState *c, int code, void *addr)
 
     if ((env->mcg_cap & MCG_SER_P) && addr
         && (code == BUS_MCEERR_AR || code == BUS_MCEERR_AO)) {
-        if (qemu_ram_addr_from_host(addr, &ram_addr) == NULL ||
+        ram_addr = qemu_ram_addr_from_host(addr);
+        if (ram_addr == RAM_ADDR_INVALID ||
             !kvm_physical_memory_addr_from_host(c->kvm_state, addr, &paddr)) {
             fprintf(stderr, "Hardware memory error for memory used by "
                     "QEMU itself instead of guest system!\n");
@@ -445,7 +446,8 @@ int kvm_arch_on_sigbus(int code, void *addr)
         hwaddr paddr;
 
         /* Hope we are lucky for AO MCE */
-        if (qemu_ram_addr_from_host(addr, &ram_addr) == NULL ||
+        ram_addr = qemu_ram_addr_from_host(addr);
+        if (ram_addr == RAM_ADDR_INVALID ||
             !kvm_physical_memory_addr_from_host(first_cpu->kvm_state,
                                                 addr, &paddr)) {
             fprintf(stderr, "Hardware memory error for memory used by "