From 38bee5dc94ee355640b030d28f311b03ee2f13d1 Mon Sep 17 00:00:00 2001 From: Stefano Stabellini Date: Thu, 19 May 2011 18:35:45 +0100 Subject: [PATCH] exec.c: refactor cpu_physical_memory_map Introduce qemu_ram_ptr_length that takes an address and a size as parameters rather than just an address. Refactor cpu_physical_memory_map so that we call qemu_ram_ptr_length only once rather than calling qemu_get_ram_ptr one time per page. This is not only more efficient but also tries to simplify the logic of the function. Currently we are relying on the fact that all the pages are mapped contiguously in qemu's address space: we have a check to make sure that the virtual address returned by qemu_get_ram_ptr from the second call on is consecutive. Now we are making this more explicit replacing all the calls to qemu_get_ram_ptr with a single call to qemu_ram_ptr_length passing a size argument. Signed-off-by: Stefano Stabellini CC: agraf@suse.de CC: anthony@codemonkey.ws Signed-off-by: Alexander Graf --- cpu-common.h | 1 + exec.c | 51 ++++++++++++++++++++++++++++++++++----------------- 2 files changed, 35 insertions(+), 17 deletions(-) diff --git a/cpu-common.h b/cpu-common.h index 9f59172..b027e43 100644 --- a/cpu-common.h +++ b/cpu-common.h @@ -65,6 +65,7 @@ void qemu_ram_free_from_ptr(ram_addr_t addr); void qemu_ram_remap(ram_addr_t addr, ram_addr_t length); /* This should only be used for ram local to a device. */ void *qemu_get_ram_ptr(ram_addr_t addr); +void *qemu_ram_ptr_length(target_phys_addr_t addr, target_phys_addr_t *size); /* Same but slower, to use for migration, where the order of * RAMBlocks must not change. */ void *qemu_safe_ram_ptr(ram_addr_t addr); diff --git a/exec.c b/exec.c index e11c1dd..238c173 100644 --- a/exec.c +++ b/exec.c @@ -3131,6 +3131,31 @@ void *qemu_safe_ram_ptr(ram_addr_t addr) return NULL; } +/* Return a host pointer to guest's ram. Similar to qemu_get_ram_ptr + * but takes a size argument */ +void *qemu_ram_ptr_length(target_phys_addr_t addr, target_phys_addr_t *size) +{ + if (xen_mapcache_enabled()) + return qemu_map_cache(addr, *size, 1); + else { + RAMBlock *block; + + QLIST_FOREACH(block, &ram_list.blocks, next) { + if (addr - block->offset < block->length) { + if (addr - block->offset + *size > block->length) + *size = block->length - addr + block->offset; + return block->host + (addr - block->offset); + } + } + + fprintf(stderr, "Bad ram offset %" PRIx64 "\n", (uint64_t)addr); + abort(); + + *size = 0; + return NULL; + } +} + void qemu_put_ram_ptr(void *addr) { trace_qemu_put_ram_ptr(addr); @@ -3992,14 +4017,12 @@ void *cpu_physical_memory_map(target_phys_addr_t addr, int is_write) { target_phys_addr_t len = *plen; - target_phys_addr_t done = 0; + target_phys_addr_t todo = 0; int l; - uint8_t *ret = NULL; - uint8_t *ptr; target_phys_addr_t page; unsigned long pd; PhysPageDesc *p; - unsigned long addr1; + target_phys_addr_t addr1 = addr; while (len > 0) { page = addr & TARGET_PAGE_MASK; @@ -4014,7 +4037,7 @@ void *cpu_physical_memory_map(target_phys_addr_t addr, } if ((pd & ~TARGET_PAGE_MASK) != IO_MEM_RAM) { - if (done || bounce.buffer) { + if (todo || bounce.buffer) { break; } bounce.buffer = qemu_memalign(TARGET_PAGE_SIZE, TARGET_PAGE_SIZE); @@ -4023,23 +4046,17 @@ void *cpu_physical_memory_map(target_phys_addr_t addr, if (!is_write) { cpu_physical_memory_read(addr, bounce.buffer, l); } - ptr = bounce.buffer; - } else { - addr1 = (pd & TARGET_PAGE_MASK) + (addr & ~TARGET_PAGE_MASK); - ptr = qemu_get_ram_ptr(addr1); - } - if (!done) { - ret = ptr; - } else if (ret + done != ptr) { - break; + + *plen = l; + return bounce.buffer; } len -= l; addr += l; - done += l; + todo += l; } - *plen = done; - return ret; + *plen = todo; + return qemu_ram_ptr_length(addr1, plen); } /* Unmaps a memory region previously mapped by cpu_physical_memory_map(). -- 2.7.4