From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38614) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gAY5g-00074M-8k for qemu-devel@nongnu.org; Thu, 11 Oct 2018 06:21:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gAY5d-0000yG-4H for qemu-devel@nongnu.org; Thu, 11 Oct 2018 06:21:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42596) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gAY5c-0000wa-RO for qemu-devel@nongnu.org; Thu, 11 Oct 2018 06:21:09 -0400 Date: Thu, 11 Oct 2018 11:20:56 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20181011102056.GE2483@work-vm> References: <20181009205652.10605-1-david@redhat.com> <20181009205652.10605-8-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181009205652.10605-8-david@redhat.com> Subject: Re: [Qemu-devel] [PATCH v1 7/7] memory-device: rewrite address assignment using ranges List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Hildenbrand Cc: qemu-devel@nongnu.org, "Michael S . Tsirkin" , Igor Mammedov , Markus Armbruster , Michael Roth , David Gibson , Eduardo Habkost * David Hildenbrand (david@redhat.com) wrote: > Let's rewrite it properly using ranges. This fixes certain overflows that > are right now possible. E.g. > > qemu-system-x86_64 -m 4G,slots=20,maxmem=40G -M pc \ > -object memory-backend-file,id=mem1,share,mem-path=/dev/zero,size=2G > -device pc-dimm,memdev=mem1,id=dimm1,addr=-0x40000000 > > Now properly reports an error instead of succeeding. > > "can't add memory device [0xffffffffc0000000:0x80000000], range overflow" > > Signed-off-by: David Hildenbrand > --- > hw/mem/memory-device.c | 56 +++++++++++++++++++++++++----------------- > 1 file changed, 33 insertions(+), 23 deletions(-) > > diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c > index 8be63c8032..1ca9c8e410 100644 > --- a/hw/mem/memory-device.c > +++ b/hw/mem/memory-device.c > @@ -100,9 +100,8 @@ static uint64_t memory_device_get_free_addr(MachineState *ms, > uint64_t align, uint64_t size, > Error **errp) > { > - uint64_t address_space_start, address_space_end; > GSList *list = NULL, *item; > - uint64_t new_addr = 0; > + Range as, new = range_empty; > > if (!ms->device_memory) { > error_setg(errp, "memory devices (e.g. for memory hotplug) are not " > @@ -115,13 +114,11 @@ static uint64_t memory_device_get_free_addr(MachineState *ms, > "enabled, please specify the maxmem option"); > return 0; > } > - address_space_start = ms->device_memory->base; > - address_space_end = address_space_start + > - memory_region_size(&ms->device_memory->mr); > - g_assert(address_space_end >= address_space_start); > + range_init(&as, ms->device_memory->base, > + memory_region_size(&ms->device_memory->mr)); > > - /* address_space_start indicates the maximum alignment we expect */ > - if (!QEMU_IS_ALIGNED(address_space_start, align)) { > + /* start of address space indicates the maximum alignment we expect */ > + if (!QEMU_IS_ALIGNED(range_lob(&as), align)) { > error_setg(errp, "the alignment (0x%" PRIx64 ") is not supported", > align); > return 0; > @@ -145,20 +142,26 @@ static uint64_t memory_device_get_free_addr(MachineState *ms, > } > > if (hint) { > - new_addr = *hint; > - if (new_addr < address_space_start) { > + if (!range_valid(*hint, size)) { > error_setg(errp, "can't add memory device [0x%" PRIx64 ":0x%" PRIx64 > - "] before 0x%" PRIx64, new_addr, size, > - address_space_start); > + "], range overflow", *hint, size); > return 0; > - } else if ((new_addr + size) > address_space_end) { > + } > + range_init(&new, *hint, size); > + if (range_starts_before_range(&new, &as)) { > + error_setg(errp, "can't add memory device [0x%" PRIx64 ":0x%" PRIx64 > + "] before 0x%" PRIx64, range_lob(&new), range_size(&new), > + range_lob(&as)); > + return 0; > + } else if (range_ends_after_range(&new, &as)) { > error_setg(errp, "can't add memory device [0x%" PRIx64 ":0x%" PRIx64 > - "] beyond 0x%" PRIx64, new_addr, size, > - address_space_end); > + "] beyond 0x%" PRIx64, range_lob(&new), range_size(&new), > + range_upb(&as)); Would !range_contains_range be easier here? > return 0; > } > } else { > - new_addr = address_space_start; > + /* our previous size checks make sure that this never overflows */ Hmm, which one exactly? > + range_init(&new, range_lob(&as), size); > } > > /* find address range that will fit new memory device */ > @@ -166,30 +169,37 @@ static uint64_t memory_device_get_free_addr(MachineState *ms, > for (item = list; item; item = g_slist_next(item)) { > const MemoryDeviceState *md = item->data; > const MemoryDeviceClass *mdc = MEMORY_DEVICE_GET_CLASS(OBJECT(md)); > - uint64_t md_size, md_addr; > + uint64_t next_addr; > + Range tmp; > > - md_addr = mdc->get_addr(md); > - md_size = memory_device_get_region_size(md, &error_abort); > + range_init(&tmp, mdc->get_addr(md), > + memory_device_get_region_size(md, &error_abort)); > > - if (ranges_overlap(md_addr, md_size, new_addr, size)) { > + if (range_overlaps_range(&tmp, &new)) { > if (hint) { > const DeviceState *d = DEVICE(md); > error_setg(errp, "address range conflicts with memory device" > " id='%s'", d->id ? d->id : "(unnamed)"); > goto out; > } > - new_addr = QEMU_ALIGN_UP(md_addr + md_size, align); > + > + next_addr = QEMU_ALIGN_UP(range_upb(&tmp) + 1, align); > + if (!range_valid(next_addr, size)) { > + range_make_empty(&new); > + break; > + } > + range_init(&new, next_addr, size); > } > } > > - if (new_addr + size > address_space_end) { > + if (!range_contains_range(&as, &new)) { > error_setg(errp, "could not find position in guest address space for " > "memory device - memory fragmented due to alignments"); > goto out; > } > out: > g_slist_free(list); > - return new_addr; > + return range_lob(&new); > } > > MemoryDeviceInfoList *qmp_memory_device_list(void) > -- > 2.17.1 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK