From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44861) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UulFk-0001Q8-Pc for qemu-devel@nongnu.org; Thu, 04 Jul 2013 11:15:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UulFh-0005PY-T5 for qemu-devel@nongnu.org; Thu, 04 Jul 2013 11:15:24 -0400 Received: from mail-wg0-x229.google.com ([2a00:1450:400c:c00::229]:61447) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UulFh-0005P2-IB for qemu-devel@nongnu.org; Thu, 04 Jul 2013 11:15:21 -0400 Received: by mail-wg0-f41.google.com with SMTP id y10so6537639wgg.4 for ; Thu, 04 Jul 2013 08:15:21 -0700 (PDT) Received: from playground.station (net-37-117-148-210.cust.dsl.vodafone.it. [37.117.148.210]) by mx.google.com with ESMTPSA id d8sm4212546wiz.0.2013.07.04.08.15.18 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Thu, 04 Jul 2013 08:15:20 -0700 (PDT) Sender: Paolo Bonzini From: Paolo Bonzini Date: Thu, 4 Jul 2013 17:13:24 +0200 Message-Id: <1372950842-32422-29-git-send-email-pbonzini@redhat.com> In-Reply-To: <1372950842-32422-1-git-send-email-pbonzini@redhat.com> References: <1372950842-32422-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 28/66] exec: reorganize address_space_map List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org First of all, rename "todo" to "done". Second, clearly separate the case of done == 0 with the case of done != 0. This will help handling reference counting in the next patch. Third, this test: if (memory_region_get_ram_addr(mr) + xlat != raddr + todo) { does not guarantee that the memory region is the same across two iterations of the while loop. For example, you could have two blocks: A) size 640 K, mapped at physical address 0, ram_addr_t 0 B) size 64 K, mapped at physical address 0xa0000, ram_addr_t 0xa0000 then mapping 1 M starting at physical address zero will erroneously treat B as the continuation of block A. qemu_ram_ptr_length ensures that no invalid memory is accessed, but it is still a pointless complication of the algorithm. The patch makes the logic clearer with an explicit test that the memory region is the same. Reviewed-by: Jan Kiszka Signed-off-by: Paolo Bonzini --- exec.c | 71 +++++++++++++++++++++++++++++++++++------------------------------- 1 file changed, 38 insertions(+), 33 deletions(-) diff --git a/exec.c b/exec.c index 307efea..a994bc8 100644 --- a/exec.c +++ b/exec.c @@ -2065,47 +2065,52 @@ void *address_space_map(AddressSpace *as, bool is_write) { hwaddr len = *plen; - hwaddr todo = 0; - hwaddr l, xlat; - MemoryRegion *mr; - ram_addr_t raddr = RAM_ADDR_MAX; - ram_addr_t rlen; - void *ret; + hwaddr done = 0; + hwaddr l, xlat, base; + MemoryRegion *mr, *this_mr; + ram_addr_t raddr; - while (len > 0) { - l = len; - mr = address_space_translate(as, addr, &xlat, &l, is_write); - - if (!memory_access_is_direct(mr, is_write)) { - if (todo || bounce.buffer) { - break; - } - bounce.buffer = qemu_memalign(TARGET_PAGE_SIZE, TARGET_PAGE_SIZE); - bounce.addr = addr; - bounce.len = l; - if (!is_write) { - address_space_read(as, addr, bounce.buffer, l); - } + if (len == 0) { + return NULL; + } - *plen = l; - return bounce.buffer; + l = len; + mr = address_space_translate(as, addr, &xlat, &l, is_write); + if (!memory_access_is_direct(mr, is_write)) { + if (bounce.buffer) { + return NULL; } - if (!todo) { - raddr = memory_region_get_ram_addr(mr) + xlat; - } else { - if (memory_region_get_ram_addr(mr) + xlat != raddr + todo) { - break; - } + bounce.buffer = qemu_memalign(TARGET_PAGE_SIZE, TARGET_PAGE_SIZE); + bounce.addr = addr; + bounce.len = l; + if (!is_write) { + address_space_read(as, addr, bounce.buffer, l); } + *plen = l; + return bounce.buffer; + } + + base = xlat; + raddr = memory_region_get_ram_addr(mr); + + for (;;) { len -= l; addr += l; - todo += l; + done += l; + if (len == 0) { + break; + } + + l = len; + this_mr = address_space_translate(as, addr, &xlat, &l, is_write); + if (this_mr != mr || xlat != base + done) { + break; + } } - rlen = todo; - ret = qemu_ram_ptr_length(raddr, &rlen); - *plen = rlen; - return ret; + + *plen = done; + return qemu_ram_ptr_length(raddr + base, plen); } /* Unmaps a memory region previously mapped by address_space_map(). -- 1.8.1.4