From f8ed85ac992c48814d916d5df4d44f9a971c5de4 Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Fri, 11 Sep 2015 16:51:43 +0200 Subject: Fix bad error handling after memory_region_init_ram() Symptom: $ qemu-system-x86_64 -m 10000000 Unexpected error in ram_block_add() at /work/armbru/qemu/exec.c:1456: upstream-qemu: cannot set up guest memory 'pc.ram': Cannot allocate memory Aborted (core dumped) Root cause: commit ef701d7 screwed up handling of out-of-memory conditions. Before the commit, we report the error and exit(1), in one place, ram_block_add(). The commit lifts the error handling up the call chain some, to three places. Fine. Except it uses &error_abort in these places, changing the behavior from exit(1) to abort(), and thus undoing the work of commit 3922825 "exec: Don't abort when we can't allocate guest memory". The three places are: * memory_region_init_ram() Commit 4994653 (right after commit ef701d7) lifted the error handling further, through memory_region_init_ram(), multiplying the incorrect use of &error_abort. Later on, imitation of existing (bad) code may have created more. * memory_region_init_ram_ptr() The &error_abort is still there. * memory_region_init_rom_device() Doesn't need fixing, because commit 33e0eb5 (soon after commit ef701d7) lifted the error handling further, and in the process changed it from &error_abort to passing it up the call chain. Correct, because the callers are realize() methods. Fix the error handling after memory_region_init_ram() with a Coccinelle semantic patch: @r@ expression mr, owner, name, size, err; position p; @@ memory_region_init_ram(mr, owner, name, size, ( - &error_abort + &error_fatal | err@p ) ); @script:python@ p << r.p; @@ print "%s:%s:%s" % (p[0].file, p[0].line, p[0].column) When the last argument is &error_abort, it gets replaced by &error_fatal. This is the fix. If the last argument is anything else, its position is reported. This lets us check the fix is complete. Four positions get reported: * ram_backend_memory_alloc() Error is passed up the call chain, ultimately through user_creatable_complete(). As far as I can tell, it's callers all handle the error sanely. * fsl_imx25_realize(), fsl_imx31_realize(), dp8393x_realize() DeviceClass.realize() methods, errors handled sanely further up the call chain. We're good. Test case again behaves: $ qemu-system-x86_64 -m 10000000 qemu-system-x86_64: cannot set up guest memory 'pc.ram': Cannot allocate memory [Exit 1 ] The next commits will repair the rest of commit ef701d7's damage. Signed-off-by: Markus Armbruster Message-Id: <1441983105-26376-3-git-send-email-armbru@redhat.com> Reviewed-by: Peter Crosthwaite --- hw/moxie/moxiesim.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'hw/moxie/moxiesim.c') diff --git a/hw/moxie/moxiesim.c b/hw/moxie/moxiesim.c index 80bcc5b..5e69e11 100644 --- a/hw/moxie/moxiesim.c +++ b/hw/moxie/moxiesim.c @@ -123,11 +123,11 @@ static void moxiesim_init(MachineState *machine) qemu_register_reset(main_cpu_reset, cpu); /* Allocate RAM. */ - memory_region_init_ram(ram, NULL, "moxiesim.ram", ram_size, &error_abort); + memory_region_init_ram(ram, NULL, "moxiesim.ram", ram_size, &error_fatal); vmstate_register_ram_global(ram); memory_region_add_subregion(address_space_mem, ram_base, ram); - memory_region_init_ram(rom, NULL, "moxie.rom", 128*0x1000, &error_abort); + memory_region_init_ram(rom, NULL, "moxie.rom", 128*0x1000, &error_fatal); vmstate_register_ram_global(rom); memory_region_add_subregion(get_system_memory(), 0x1000, rom); -- cgit v1.1