Received: from eggs.gnu.org ([2001:4830:134:3::10]:49824) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZjSN6-0003rq-A6 for qemu-devel@nongnu.org; Tue, 06 Oct 2015 09:33:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZjSN2-0004IJ-Rw for qemu-devel@nongnu.org; Tue, 06 Oct 2015 09:33:36 -0400 Received: from mailout1.w1.samsung.com ([210.118.77.11]:21801) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZjSN2-0004Hs-Jy for qemu-devel@nongnu.org; Tue, 06 Oct 2015 09:33:32 -0400 Received: from eucpsbgm2.samsung.com (unknown [203.254.199.245]) by mailout1.w1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0NVS00JCHWBTK0C0@mailout1.w1.samsung.com> for qemu-devel@nongnu.org; Tue, 06 Oct 2015 14:33:29 +0100 (BST) From: Pavel Fedin Date: Tue, 06 Oct 2015 16:33:23 +0300 Message-id: <017e01d1003b$959bc820$c0d35860$@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit Content-language: ru Subject: [Qemu-devel] [PATCH v4] ivshmem: allow the sharing of hugepages List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: 'Michael Tokarev' This patch permits to share memory areas that do not specifically belong to /dev/shm. In such case, the file must be already present when launching qemu. A new parameter 'file' has been added to specify the file to use. A use case for this patch is sharing huge pages available through a hugetlbfs mountpoint. Signed-off-by: Damien Millescamps Signed-off-by: Pavel Fedin --- 2 years passed since the last review of this, and the original author never came back. So i decided to pick up this work because my project is interested in this feature. I am keeping patch version numbering, but the original changelog was lost. Relevant thread here: https://lists.gnu.org/archive/html/qemu-trivial/2013-09/msg00148.html v3 => v4: - Fixed documentation and wordings according to the last review - Report also actual error messages - Added missing exit() - Fixed up code style according to latest checkpatch rules --- docs/specs/ivshmem_device_spec.txt | 7 ++-- hw/misc/ivshmem.c | 67 +++++++++++++++++++++++++------------- 2 files changed, 50 insertions(+), 24 deletions(-) diff --git a/docs/specs/ivshmem_device_spec.txt b/docs/specs/ivshmem_device_spec.txt index 667a862..8b108e7 100644 --- a/docs/specs/ivshmem_device_spec.txt +++ b/docs/specs/ivshmem_device_spec.txt @@ -4,8 +4,11 @@ Device Specification for Inter-VM shared memory device The Inter-VM shared memory device is designed to share a region of memory to userspace in multiple virtual guests. The memory region does not belong to any -guest, but is a POSIX memory object on the host. Optionally, the device may -support sending interrupts to other guests sharing the same memory region. +guest, but is a either a POSIX memory object or a mmap'd file (for instance, +hugepage-backed file) on the host. + +Optionally, the device may support sending interrupts to other guests sharing +the same memory region. The Inter-VM PCI device diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c index cc76989..999ed7d 100644 --- a/hw/misc/ivshmem.c +++ b/hw/misc/ivshmem.c @@ -100,9 +100,10 @@ typedef struct IVShmemState { Error *migration_blocker; - char * shmobj; - char * sizearg; - char * role; + char *shmobj; + char *fileobj; + char *sizearg; + char *role; int role_val; /* scalar to avoid multiple string comparisons */ } IVShmemState; @@ -769,9 +770,9 @@ static int pci_ivshmem_init(PCIDevice *dev) /* if we get a UNIX socket as the parameter we will talk * to the ivshmem server to receive the memory region */ - if (s->shmobj != NULL) { + if (s->shmobj != NULL || s->fileobj != NULL) { error_report("WARNING: do not specify both 'chardev' " - "and 'shm' with ivshmem"); + "and 'shm' or 'file' with ivshmem"); } IVSHMEM_DPRINTF("using shared memory server (socket = %s)\n", @@ -797,28 +798,49 @@ static int pci_ivshmem_init(PCIDevice *dev) } else { /* just map the file immediately, we're not using a server */ int fd; + int is_shm = !!(s->shmobj != NULL); + int is_file = !!(s->fileobj != NULL); - if (s->shmobj == NULL) { - error_report("Must specify 'chardev' or 'shm' to ivshmem"); + if (!(is_shm ^ is_file)) { + error_report("Must specify one of 'chardev', 'shm' or 'file' " + "to ivshmem"); exit(1); } - IVSHMEM_DPRINTF("using shm_open (shm object = %s)\n", s->shmobj); - - /* try opening with O_EXCL and if it succeeds zero the memory - * by truncating to 0 */ - if ((fd = shm_open(s->shmobj, O_CREAT|O_RDWR|O_EXCL, - S_IRWXU|S_IRWXG|S_IRWXO)) > 0) { - /* truncate file to length PCI device's memory */ - if (ftruncate(fd, s->ivshmem_size) != 0) { - error_report("could not truncate shared file"); + if (is_shm) { + IVSHMEM_DPRINTF("using shm_open (shm object = %s)\n", s->shmobj); + + /* try opening with O_EXCL and if it succeeds zero the memory + * by truncating to 0 */ + fd = shm_open(s->shmobj, O_CREAT|O_RDWR|O_EXCL, + S_IRWXU|S_IRWXG|S_IRWXO); + if (fd > 0) { + /* truncate file to length PCI device's memory */ + if (ftruncate(fd, s->ivshmem_size) != 0) { + error_report("could not truncate shared file: %s", + strerror(errno)); + exit(1); + } + } else { + fd = shm_open(s->shmobj, O_CREAT|O_RDWR, + S_IRWXU|S_IRWXG|S_IRWXO); + if (fd < 0) { + error_report("could not open shared file: %s", + strerror(errno)); + exit(1); + } + } + } else { + IVSHMEM_DPRINTF("using open (file object = %s)\n", s->fileobj); + + /* try opening a mmap's file. This file must have been previously + * created on the host */ + fd = open(s->fileobj, O_RDWR); + if (fd < 0) { + error_report("ivshmem: could not open file: %s\n", + strerror(errno)); + exit(-1); } - - } else if ((fd = shm_open(s->shmobj, O_CREAT|O_RDWR, - S_IRWXU|S_IRWXG|S_IRWXO)) < 0) { - error_report("could not open shared file"); - exit(1); - } if (check_shm_size(s, fd) == -1) { @@ -856,6 +878,7 @@ static Property ivshmem_properties[] = { DEFINE_PROP_BIT("ioeventfd", IVShmemState, features, IVSHMEM_IOEVENTFD, false), DEFINE_PROP_BIT("msi", IVShmemState, features, IVSHMEM_MSI, true), DEFINE_PROP_STRING("shm", IVShmemState, shmobj), + DEFINE_PROP_STRING("file", IVShmemState, fileobj), DEFINE_PROP_STRING("role", IVShmemState, role), DEFINE_PROP_UINT32("use64", IVShmemState, ivshmem_64bit, 1), DEFINE_PROP_END_OF_LIST(), -- 1.9.5.msysgit.0