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[Qemu-devel] [PULL v2 31/40] ivshmem: Implement shm=... with a memory ba
From: |
Markus Armbruster |
Subject: |
[Qemu-devel] [PULL v2 31/40] ivshmem: Implement shm=... with a memory backend |
Date: |
Mon, 21 Mar 2016 21:43:54 +0100 |
ivshmem has its very own code to create and map shared memory.
Replace that with an implicitly created memory backend. Reduces the
number of ways we create BAR 2 from three to two.
The memory-backend-file is currently available only with CONFIG_LINUX,
so this adds a second Linuxism to ivshmem (the other one is eventfd).
Should we ever need to make it portable to systems where
memory-backend-file can't be made to serve, we could create a
memory-backend-shmem that allocates memory with shm_open().
Bonus fix: shared memory files are now created with permissions 0655
instead of 0777.
Signed-off-by: Markus Armbruster <address@hidden>
Reviewed-by: Paolo Bonzini <address@hidden>
Message-Id: <address@hidden>
---
hw/misc/ivshmem.c | 79 ++++++++++++++++---------------------------------------
1 file changed, 23 insertions(+), 56 deletions(-)
diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
index 66c713e..138ae9d 100644
--- a/hw/misc/ivshmem.c
+++ b/hw/misc/ivshmem.c
@@ -26,6 +26,7 @@
#include "migration/migration.h"
#include "qemu/error-report.h"
#include "qemu/event_notifier.h"
+#include "qom/object_interfaces.h"
#include "sysemu/char.h"
#include "sysemu/hostmem.h"
#include "qapi/visitor.h"
@@ -369,31 +370,6 @@ static int check_shm_size(IVShmemState *s, int fd, Error
**errp)
}
}
-/* create the shared memory BAR when we are not using the server, so we can
- * create the BAR and map the memory immediately */
-static int create_shared_memory_BAR(IVShmemState *s, int fd, uint8_t attr,
- Error **errp)
-{
- void * ptr;
-
- ptr = mmap(0, s->ivshmem_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
- if (ptr == MAP_FAILED) {
- error_setg_errno(errp, errno, "Failed to mmap shared memory");
- return -1;
- }
-
- memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s), "ivshmem.bar2",
- s->ivshmem_size, ptr);
- qemu_set_ram_fd(memory_region_get_ram_addr(&s->ivshmem), fd);
- vmstate_register_ram(&s->ivshmem, DEVICE(s));
- memory_region_add_subregion(&s->bar, 0, &s->ivshmem);
-
- /* region for shared memory */
- pci_register_bar(PCI_DEVICE(s), 2, attr, &s->bar);
-
- return 0;
-}
-
static void ivshmem_add_eventfd(IVShmemState *s, int posn, int i)
{
memory_region_add_eventfd(&s->ivshmem_mmio,
@@ -837,6 +813,23 @@ static void ivshmem_write_config(PCIDevice *pdev, uint32_t
address,
}
}
+static void desugar_shm(IVShmemState *s)
+{
+ Object *obj;
+ char *path;
+
+ obj = object_new("memory-backend-file");
+ path = g_strdup_printf("/dev/shm/%s", s->shmobj);
+ object_property_set_str(obj, path, "mem-path", &error_abort);
+ g_free(path);
+ object_property_set_int(obj, s->ivshmem_size, "size", &error_abort);
+ object_property_set_bool(obj, true, "share", &error_abort);
+ object_property_add_child(OBJECT(s), "internal-shm-backend", obj,
+ &error_abort);
+ user_creatable_complete(obj, &error_abort);
+ s->hostmem = MEMORY_BACKEND(obj);
+}
+
static void pci_ivshmem_realize(PCIDevice *dev, Error **errp)
{
IVShmemState *s = IVSHMEM(dev);
@@ -915,6 +908,10 @@ static void pci_ivshmem_realize(PCIDevice *dev, Error
**errp)
attr |= PCI_BASE_ADDRESS_MEM_TYPE_64;
}
+ if (s->shmobj) {
+ desugar_shm(s);
+ }
+
if (s->hostmem != NULL) {
MemoryRegion *mr;
@@ -925,7 +922,7 @@ static void pci_ivshmem_realize(PCIDevice *dev, Error
**errp)
vmstate_register_ram(mr, DEVICE(s));
memory_region_add_subregion(&s->bar, 0, mr);
pci_register_bar(PCI_DEVICE(s), 2, attr, &s->bar);
- } else if (s->server_chr != NULL) {
+ } else {
IVSHMEM_DPRINTF("using shared memory server (socket = %s)\n",
s->server_chr->filename);
@@ -952,36 +949,6 @@ static void pci_ivshmem_realize(PCIDevice *dev, Error
**errp)
error_setg(errp, "failed to initialize interrupts");
return;
}
- } else {
- /* just map the file immediately, we're not using a server */
- int fd;
-
- 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");
- }
-
- } else if ((fd = shm_open(s->shmobj, O_CREAT|O_RDWR,
- S_IRWXU|S_IRWXG|S_IRWXO)) < 0) {
- error_setg(errp, "could not open shared file");
- return;
- }
-
- if (check_shm_size(s, fd, errp) == -1) {
- return;
- }
-
- create_shared_memory_BAR(s, fd, attr, &err);
- if (err) {
- error_propagate(errp, err);
- return;
- }
}
if (s->role_val == IVSHMEM_PEER) {
--
2.4.3
- [Qemu-devel] [PULL v2 34/40] qdev: New DEFINE_PROP_ON_OFF_AUTO, (continued)
- [Qemu-devel] [PULL v2 34/40] qdev: New DEFINE_PROP_ON_OFF_AUTO, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 38/40] ivshmem: Drop ivshmem property x-memdev, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 06/40] tests/libqos/pci-pc: Fix qpci_pc_iomap() to map BARs aligned, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 11/40] ivshmem: Add missing newlines to debug printfs, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 14/40] ivshmem: Drop ivshmem_event() stub, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 15/40] ivshmem: Don't destroy the chardev on version mismatch, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 24/40] ivshmem: Plug leaks on unplug, fix peer disconnect, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 20/40] ivshmem: Leave INTx alone when using MSI-X, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 27/40] ivshmem: Rely on server sending the ID right after the version, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 29/40] ivshmem: Simplify how we cope with short reads from server, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 31/40] ivshmem: Implement shm=... with a memory backend,
Markus Armbruster <=
- [Qemu-devel] [PULL v2 35/40] ivshmem: Replace int role_val by OnOffAuto master, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 01/40] target-ppc: Document TOCTTOU in hugepage support, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 25/40] ivshmem: Receive shared memory synchronously in realize(), Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 10/40] ivshmem: Rewrite specification document, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 39/40] ivshmem: Require master to have ID zero, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 03/40] ivshmem-server: Don't overload POSIX shmem and file name, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 19/40] ivshmem: Clean up MSI-X conditions, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 32/40] ivshmem: Simplify memory regions for BAR 2 (shared memory), Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 37/40] ivshmem: Clean up after the previous commit, Markus Armbruster, 2016/03/21
- [Qemu-devel] [PULL v2 26/40] ivshmem: Propagate errors through ivshmem_recv_setup(), Markus Armbruster, 2016/03/21