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[Qemu-devel] [PULL 33/45] exec: make qemu_ram_ptr_length more similar to
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PULL 33/45] exec: make qemu_ram_ptr_length more similar to qemu_get_ram_ptr |
Date: |
Thu, 17 Dec 2015 18:46:29 +0100 |
Notably, use qemu_get_ram_block to enjoy the MRU optimization.
Signed-off-by: Paolo Bonzini <address@hidden>
---
exec.c | 46 +++++++++++++++++++++++-----------------------
1 file changed, 23 insertions(+), 23 deletions(-)
diff --git a/exec.c b/exec.c
index af95438..069848b 100644
--- a/exec.c
+++ b/exec.c
@@ -1809,36 +1809,33 @@ void *qemu_get_ram_ptr(ram_addr_t addr)
/* Return a host pointer to guest's ram. Similar to qemu_get_ram_ptr
* but takes a size argument.
*
- * 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.
+ * Called within RCU critical section.
*/
static void *qemu_ram_ptr_length(ram_addr_t addr, hwaddr *size)
{
- void *ptr;
+ RAMBlock *block;
+ ram_addr_t offset_inside_block;
if (*size == 0) {
return NULL;
}
- if (xen_enabled()) {
- return xen_map_cache(addr, *size, 1);
- } else {
- RAMBlock *block;
- rcu_read_lock();
- QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
- if (addr - block->offset < block->max_length) {
- if (addr - block->offset + *size > block->max_length)
- *size = block->max_length - addr + block->offset;
- ptr = ramblock_ptr(block, addr - block->offset);
- rcu_read_unlock();
- return ptr;
- }
+
+ block = qemu_get_ram_block(addr);
+ offset_inside_block = addr - block->offset;
+ *size = MIN(*size, block->max_length - offset_inside_block);
+
+ if (xen_enabled() && block->host == NULL) {
+ /* We need to check if the requested address is in the RAM
+ * because we don't want to map the entire memory in QEMU.
+ * In that case just map the requested area.
+ */
+ if (block->offset == 0) {
+ return xen_map_cache(addr, *size, 1);
}
- fprintf(stderr, "Bad ram offset %" PRIx64 "\n", (uint64_t)addr);
- abort();
+ block->host = xen_map_cache(block->offset, block->max_length, 1);
}
+
+ return ramblock_ptr(block, offset_inside_block);
}
/*
@@ -2786,6 +2783,7 @@ void *address_space_map(AddressSpace *as,
hwaddr l, xlat, base;
MemoryRegion *mr, *this_mr;
ram_addr_t raddr;
+ void *ptr;
if (len == 0) {
return NULL;
@@ -2837,9 +2835,11 @@ void *address_space_map(AddressSpace *as,
}
memory_region_ref(mr);
- rcu_read_unlock();
*plen = done;
- return qemu_ram_ptr_length(raddr + base, plen);
+ ptr = qemu_ram_ptr_length(raddr + base, plen);
+ rcu_read_unlock();
+
+ return ptr;
}
/* Unmaps a memory region previously mapped by address_space_map().
--
2.5.0
- [Qemu-devel] [PULL 34/45] memory: reorder MemoryRegion fields, (continued)
- [Qemu-devel] [PULL 34/45] memory: reorder MemoryRegion fields, Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 31/45] linux-user: convert DEBUG_SIGNAL logging to tracepoints, Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 30/45] linux-user: avoid "naked" qemu_log, Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 28/45] xtensa: avoid "naked" qemu_log, Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 35/45] memory: avoid unnecessary object_ref/unref, Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 40/45] rcu: optimize rcu_read_lock, Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 37/45] memory: extract first iteration of address_space_read and address_space_write, Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 41/45] target-i386: kvm: clear unusable segments' flags in migration, Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 43/45] scsi: always call notifier on async cancellation, Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 44/45] coverity: Model g_poll(), Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 33/45] exec: make qemu_ram_ptr_length more similar to qemu_get_ram_ptr,
Paolo Bonzini <=
- [Qemu-devel] [PULL 36/45] memory: split address_space_read and address_space_write, Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 38/45] memory: inline a few small accessors, Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 39/45] memory: try to inline constant-length reads, Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 42/45] scsi: use scsi_req_cancel_async when purging requests, Paolo Bonzini, 2015/12/17
- [Qemu-devel] [PULL 45/45] coverity: Model g_memdup(), Paolo Bonzini, 2015/12/17
- Re: [Qemu-devel] [PULL 00/45] KVM, memory, SCSI, qemu_log, Coverity patches for 2015-12-17, Peter Maydell, 2015/12/17