[PATCH v4 15/17] xen: mapcache: Remove assumption of RAMBlock with 0 offset

["Edgar E. Iglesias" <edgar.iglesias@xxxxxxxxx>]

From: "Edgar E. Iglesias" <edgar.iglesias@xxxxxxx>

The current mapcache assumes that all memory is mapped
in a single RAM MR (the first one with offset 0). Remove
this assumption and propagate the offset to the mapcache
so it can do reverse mappings (from hostptr -> ram_addr).

This is in preparation for adding grant mappings.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xxxxxxx>
---
 hw/xen/xen-mapcache.c         | 25 ++++++++++++++++++-------
 include/sysemu/xen-mapcache.h |  2 ++
 system/physmem.c              |  8 ++++----
 3 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/hw/xen/xen-mapcache.c b/hw/xen/xen-mapcache.c
index 09b5f36d9c..1b32d0c003 100644
--- a/hw/xen/xen-mapcache.c
+++ b/hw/xen/xen-mapcache.c
@@ -43,6 +43,9 @@ typedef struct MapCacheEntry {
 #define XEN_MAPCACHE_ENTRY_DUMMY (1 << 0)
     uint8_t flags;
     hwaddr size;
+
+    /* Keep ram_addr offset for reverse mappings (hostptr -> ram_addr).  */
+    ram_addr_t ram_offset;
     struct MapCacheEntry *next;
 } MapCacheEntry;
 
@@ -165,7 +168,8 @@ static void xen_remap_bucket(MapCache *mc,
                              void *vaddr,
                              hwaddr size,
                              hwaddr address_index,
-                             bool dummy)
+                             bool dummy,
+                             ram_addr_t ram_offset)
 {
     uint8_t *vaddr_base;
     xen_pfn_t *pfns;
@@ -244,6 +248,7 @@ static void xen_remap_bucket(MapCache *mc,
     entry->size = size;
     entry->valid_mapping = g_new0(unsigned long,
                                   BITS_TO_LONGS(size >> XC_PAGE_SHIFT));
+    entry->ram_offset = ram_offset;
 
     if (dummy) {
         entry->flags |= XEN_MAPCACHE_ENTRY_DUMMY;
@@ -264,6 +269,7 @@ static void xen_remap_bucket(MapCache *mc,
 
 static uint8_t *xen_map_cache_unlocked(MapCache *mc,
                                        hwaddr phys_addr, hwaddr size,
+                                       ram_addr_t ram_offset,
                                        uint8_t lock, bool dma, bool is_write)
 {
     MapCacheEntry *entry, *pentry = NULL,
@@ -335,14 +341,16 @@ tryagain:
     if (!entry) {
         entry = g_new0(MapCacheEntry, 1);
         pentry->next = entry;
-        xen_remap_bucket(mc, entry, NULL, cache_size, address_index, dummy);
+        xen_remap_bucket(mc, entry, NULL, cache_size, address_index, dummy,
+                         ram_offset);
     } else if (!entry->lock) {
         if (!entry->vaddr_base || entry->paddr_index != address_index ||
                 entry->size != cache_size ||
                 !test_bits(address_offset >> XC_PAGE_SHIFT,
                     test_bit_size >> XC_PAGE_SHIFT,
                     entry->valid_mapping)) {
-            xen_remap_bucket(mc, entry, NULL, cache_size, address_index, 
dummy);
+            xen_remap_bucket(mc, entry, NULL, cache_size, address_index, dummy,
+                             ram_offset);
         }
     }
 
@@ -389,13 +397,15 @@ tryagain:
 
 uint8_t *xen_map_cache(MemoryRegion *mr,
                        hwaddr phys_addr, hwaddr size,
+                       ram_addr_t ram_addr_offset,
                        uint8_t lock, bool dma,
                        bool is_write)
 {
     uint8_t *p;
 
     mapcache_lock(mapcache);
-    p = xen_map_cache_unlocked(mapcache, phys_addr, size, lock, dma, is_write);
+    p = xen_map_cache_unlocked(mapcache, phys_addr, size, ram_addr_offset,
+                               lock, dma, is_write);
     mapcache_unlock(mapcache);
     return p;
 }
@@ -432,7 +442,8 @@ static ram_addr_t 
xen_ram_addr_from_mapcache_single(MapCache *mc, void *ptr)
         raddr = RAM_ADDR_INVALID;
     } else {
         raddr = (reventry->paddr_index << mc->bucket_shift) +
-             ((unsigned long) ptr - (unsigned long) entry->vaddr_base);
+             ((unsigned long) ptr - (unsigned long) entry->vaddr_base) +
+             entry->ram_offset;
     }
     mapcache_unlock(mc);
     return raddr;
@@ -627,8 +638,8 @@ static uint8_t *xen_replace_cache_entry_unlocked(MapCache 
*mc,
 
     trace_xen_replace_cache_entry_dummy(old_phys_addr, new_phys_addr);
 
-    xen_remap_bucket(mapcache, entry, entry->vaddr_base,
-                     cache_size, address_index, false);
+    xen_remap_bucket(mc, entry, entry->vaddr_base,
+                     cache_size, address_index, false, entry->ram_offset);
     if (!test_bits(address_offset >> XC_PAGE_SHIFT,
                 test_bit_size >> XC_PAGE_SHIFT,
                 entry->valid_mapping)) {
diff --git a/include/sysemu/xen-mapcache.h b/include/sysemu/xen-mapcache.h
index 1ec9e66752..b5e3ea1bc0 100644
--- a/include/sysemu/xen-mapcache.h
+++ b/include/sysemu/xen-mapcache.h
@@ -19,6 +19,7 @@ typedef hwaddr (*phys_offset_to_gaddr_t)(hwaddr phys_offset,
 void xen_map_cache_init(phys_offset_to_gaddr_t f,
                         void *opaque);
 uint8_t *xen_map_cache(MemoryRegion *mr, hwaddr phys_addr, hwaddr size,
+                       ram_addr_t ram_addr_offset,
                        uint8_t lock, bool dma,
                        bool is_write);
 ram_addr_t xen_ram_addr_from_mapcache(void *ptr);
@@ -37,6 +38,7 @@ static inline void xen_map_cache_init(phys_offset_to_gaddr_t 
f,
 static inline uint8_t *xen_map_cache(MemoryRegion *mr,
                                      hwaddr phys_addr,
                                      hwaddr size,
+                                     ram_addr_t ram_addr_offset,
                                      uint8_t lock,
                                      bool dma,
                                      bool is_write)
diff --git a/system/physmem.c b/system/physmem.c
index 1a5ffcba2a..5b16eeccca 100644
--- a/system/physmem.c
+++ b/system/physmem.c
@@ -2228,13 +2228,13 @@ static void *qemu_ram_ptr_length(RAMBlock *block, 
ram_addr_t addr,
          * In that case just map the requested area.
          */
         if (xen_mr_is_memory(block->mr)) {
-            return xen_map_cache(block->mr, addr, len, lock, lock,
-                                 is_write);
+            return xen_map_cache(block->mr, addr, len, block->offset,
+                                 lock, lock, is_write);
         }
 
         block->host = xen_map_cache(block->mr, block->offset,
-                                    block->max_length, 1,
-                                    lock, is_write);
+                                    block->max_length, 0,
+                                    1, lock, is_write);
     }
 
     return ramblock_ptr(block, addr);
-- 
2.40.1