| Message ID | 1456771254-17511-31-git-send-email-armbru@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 29/02/2016 19:40, Markus Armbruster wrote: > ivshmem_realize() puts the shared memory region in a container region. > Used to be necessary to permit delayed mapping of the shared memory. > Now we don't do that anymore, the container is redundant. Drop it. Can you explain why we don't do that anymore to someone who hasn't read patches 4 to 28? :-) Is it patch 23? Paolo
On 29/02/2016 19:40, Markus Armbruster wrote: > - memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s), > + s->ivshmem_bar2 = g_new(MemoryRegion, 1); > + memory_region_init_ram_ptr(s->ivshmem_bar2, OBJECT(s), > "ivshmem.bar2", s->ivshmem_size, ptr); > - qemu_set_ram_fd(s->ivshmem.ram_addr, fd); > - vmstate_register_ram(&s->ivshmem, DEVICE(s)); > - memory_region_add_subregion(&s->bar, 0, &s->ivshmem); > + qemu_set_ram_fd(s->ivshmem_bar2->ram_addr, fd); This is missing an instance_finalize callback to do if (s->ivshmem_bar2) { object_unparent(s->ivshmem_bar2); g_free(s->ivshmem_bar2); } or, alternatively just use a flag (e.g. s->bar2_mapped) and allocate it directly in the IVShmemState struct. Paolo
Paolo Bonzini <pbonzini@redhat.com> writes: > On 29/02/2016 19:40, Markus Armbruster wrote: >> ivshmem_realize() puts the shared memory region in a container region. >> Used to be necessary to permit delayed mapping of the shared memory. >> Now we don't do that anymore, the container is redundant. Drop it. > > Can you explain why we don't do that anymore to someone who hasn't read > patches 4 to 28? :-) Is it patch 23? Yes, but you also need 24 to complete the job. Commit message could perhaps explain it like this: ivshmem_realize() puts the shared memory region in a container region. Used to be necessary to permit delayed mapping of the shared memory. However, we recently moved to synchronous mapping, in "ivshmem: Receive shared memory synchronously in realize()" and the commit following it. The container is redundant since then. Drop it. Better?
On 01/03/2016 13:14, Markus Armbruster wrote: >> > Can you explain why we don't do that anymore to someone who hasn't read >> > patches 4 to 28? :-) Is it patch 23? > Yes, but you also need 24 to complete the job. > > Commit message could perhaps explain it like this: > > ivshmem_realize() puts the shared memory region in a container > region. Used to be necessary to permit delayed mapping of the > shared memory. However, we recently moved to synchronous mapping, > in "ivshmem: Receive shared memory synchronously in realize()" and > the commit following it. The container is redundant since then. > Drop it. > > Better? Yes, thanks! Paolo
Paolo Bonzini <pbonzini@redhat.com> writes: > On 29/02/2016 19:40, Markus Armbruster wrote: >> - memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s), >> + s->ivshmem_bar2 = g_new(MemoryRegion, 1); >> + memory_region_init_ram_ptr(s->ivshmem_bar2, OBJECT(s), >> "ivshmem.bar2", s->ivshmem_size, ptr); >> - qemu_set_ram_fd(s->ivshmem.ram_addr, fd); >> - vmstate_register_ram(&s->ivshmem, DEVICE(s)); >> - memory_region_add_subregion(&s->bar, 0, &s->ivshmem); >> + qemu_set_ram_fd(s->ivshmem_bar2->ram_addr, fd); > > This is missing an instance_finalize callback to do > > if (s->ivshmem_bar2) { > object_unparent(s->ivshmem_bar2); > g_free(s->ivshmem_bar2); > } Since it's allocated within ivshmem_realize(), I guess I could free it in ivshmem_exit(). > or, alternatively just use a flag (e.g. s->bar2_mapped) and allocate it > directly in the IVShmemState struct. I'll see what comes out nicer. Thanks!
On 01/03/2016 15:06, Markus Armbruster wrote: > Paolo Bonzini <pbonzini@redhat.com> writes: > >> On 29/02/2016 19:40, Markus Armbruster wrote: >>> - memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s), >>> + s->ivshmem_bar2 = g_new(MemoryRegion, 1); >>> + memory_region_init_ram_ptr(s->ivshmem_bar2, OBJECT(s), >>> "ivshmem.bar2", s->ivshmem_size, ptr); >>> - qemu_set_ram_fd(s->ivshmem.ram_addr, fd); >>> - vmstate_register_ram(&s->ivshmem, DEVICE(s)); >>> - memory_region_add_subregion(&s->bar, 0, &s->ivshmem); >>> + qemu_set_ram_fd(s->ivshmem_bar2->ram_addr, fd); >> >> This is missing an instance_finalize callback to do >> >> if (s->ivshmem_bar2) { >> object_unparent(s->ivshmem_bar2); >> g_free(s->ivshmem_bar2); >> } > > Since it's allocated within ivshmem_realize(), I guess I could free it > in ivshmem_exit(). Unfortunately you can't, because the guest might be using it at the time of hot-unplug (e.g. DMAing from disk to it). Unrealize is the place where you hide stuff, and in this case the PCI core does it for you; finalize is the place where you free stuff. This is mentioned (though not really in these terms) in docs/memory.txt. Paolo >> or, alternatively just use a flag (e.g. s->bar2_mapped) and allocate it >> directly in the IVShmemState struct. > > I'll see what comes out nicer. Thanks! >
Paolo Bonzini <pbonzini@redhat.com> writes: > On 01/03/2016 15:06, Markus Armbruster wrote: >> Paolo Bonzini <pbonzini@redhat.com> writes: >> >>> On 29/02/2016 19:40, Markus Armbruster wrote: >>>> - memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s), >>>> + s->ivshmem_bar2 = g_new(MemoryRegion, 1); >>>> + memory_region_init_ram_ptr(s->ivshmem_bar2, OBJECT(s), >>>> "ivshmem.bar2", s->ivshmem_size, ptr); >>>> - qemu_set_ram_fd(s->ivshmem.ram_addr, fd); >>>> - vmstate_register_ram(&s->ivshmem, DEVICE(s)); >>>> - memory_region_add_subregion(&s->bar, 0, &s->ivshmem); >>>> + qemu_set_ram_fd(s->ivshmem_bar2->ram_addr, fd); >>> >>> This is missing an instance_finalize callback to do >>> >>> if (s->ivshmem_bar2) { >>> object_unparent(s->ivshmem_bar2); >>> g_free(s->ivshmem_bar2); >>> } >> >> Since it's allocated within ivshmem_realize(), I guess I could free it >> in ivshmem_exit(). > > Unfortunately you can't, because the guest might be using it at the time > of hot-unplug (e.g. DMAing from disk to it). Unrealize is the place > where you hide stuff, and in this case the PCI core does it for you; > finalize is the place where you free stuff. > > This is mentioned (though not really in these terms) in docs/memory.txt. You mean I'm supposed to have read and understood that?!? ;-} Thanks! [...]
diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c index 9931d5e..0440bca 100644 --- a/hw/misc/ivshmem.c +++ b/hw/misc/ivshmem.c @@ -82,12 +82,7 @@ typedef struct IVShmemState { CharDriverState *server_chr; MemoryRegion ivshmem_mmio; - /* We might need to register the BAR before we actually have the memory. - * So prepare a container MemoryRegion for the BAR immediately and - * add a subregion when we have the memory. - */ - MemoryRegion bar; - MemoryRegion ivshmem; + MemoryRegion *ivshmem_bar2; /* BAR 2 (shared memory) */ size_t ivshmem_size; /* size of shared memory region */ uint32_t ivshmem_64bit; @@ -487,7 +482,7 @@ static void process_msg_shmem(IVShmemState *s, int fd, Error **errp) Error *err = NULL; void *ptr; - if (memory_region_is_mapped(&s->ivshmem)) { + if (s->ivshmem_bar2) { error_setg(errp, "server sent unexpected shared memory message"); close(fd); return; @@ -506,11 +501,10 @@ static void process_msg_shmem(IVShmemState *s, int fd, Error **errp) close(fd); return; } - memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s), + s->ivshmem_bar2 = g_new(MemoryRegion, 1); + memory_region_init_ram_ptr(s->ivshmem_bar2, OBJECT(s), "ivshmem.bar2", s->ivshmem_size, ptr); - qemu_set_ram_fd(s->ivshmem.ram_addr, fd); - vmstate_register_ram(&s->ivshmem, DEVICE(s)); - memory_region_add_subregion(&s->bar, 0, &s->ivshmem); + qemu_set_ram_fd(s->ivshmem_bar2->ram_addr, fd); } static void process_msg_disconnect(IVShmemState *s, uint16_t posn, @@ -696,7 +690,7 @@ static void ivshmem_recv_setup(IVShmemState *s, Error **errp) } } while (msg != -1); - assert(memory_region_is_mapped(&s->ivshmem)); + assert(s->ivshmem_bar2); } /* Select the MSI-X vectors used by device. @@ -909,7 +903,6 @@ static void pci_ivshmem_realize(PCIDevice *dev, Error **errp) pci_register_bar(dev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY, &s->ivshmem_mmio); - memory_region_init(&s->bar, OBJECT(s), "ivshmem-bar2-container", s->ivshmem_size); if (s->ivshmem_64bit) { attr |= PCI_BASE_ADDRESS_MEM_TYPE_64; } @@ -919,15 +912,10 @@ static void pci_ivshmem_realize(PCIDevice *dev, Error **errp) } if (s->hostmem != NULL) { - MemoryRegion *mr; - IVSHMEM_DPRINTF("using hostmem\n"); - mr = host_memory_backend_get_memory(MEMORY_BACKEND(s->hostmem), - &error_abort); - vmstate_register_ram(mr, DEVICE(s)); - memory_region_add_subregion(&s->bar, 0, mr); - pci_register_bar(PCI_DEVICE(s), 2, attr, &s->bar); + s->ivshmem_bar2 = host_memory_backend_get_memory(s->hostmem, + &error_abort); } else { IVSHMEM_DPRINTF("using shared memory server (socket = %s)\n", s->server_chr->filename); @@ -935,8 +923,6 @@ static void pci_ivshmem_realize(PCIDevice *dev, Error **errp) /* we allocate enough space for 16 peers and grow as needed */ resize_peers(s, 16); - pci_register_bar(dev, 2, attr, &s->bar); - /* * Receive setup messages from server synchronously. * Older versions did it asynchronously, but that creates a @@ -957,6 +943,9 @@ static void pci_ivshmem_realize(PCIDevice *dev, Error **errp) } } + vmstate_register_ram(s->ivshmem_bar2, DEVICE(s)); + pci_register_bar(PCI_DEVICE(s), 2, attr, s->ivshmem_bar2); + if (s->role_val == IVSHMEM_PEER) { error_setg(&s->migration_blocker, "Migration is disabled when using feature 'peer mode' in device 'ivshmem'"); @@ -974,22 +963,19 @@ static void pci_ivshmem_exit(PCIDevice *dev) error_free(s->migration_blocker); } - if (memory_region_is_mapped(&s->ivshmem)) { + if (memory_region_is_mapped(s->ivshmem_bar2)) { if (!s->hostmem) { - void *addr = memory_region_get_ram_ptr(&s->ivshmem); - int fd; + void *addr = memory_region_get_ram_ptr(s->ivshmem_bar2); if (munmap(addr, s->ivshmem_size) == -1) { error_report("Failed to munmap shared memory %s", strerror(errno)); } - if ((fd = qemu_get_ram_fd(s->ivshmem.ram_addr)) != -1) - close(fd); + close(qemu_get_ram_fd(s->ivshmem_bar2->ram_addr)); } - vmstate_unregister_ram(&s->ivshmem, DEVICE(dev)); - memory_region_del_subregion(&s->bar, &s->ivshmem); + vmstate_unregister_ram(s->ivshmem_bar2, DEVICE(dev)); } if (s->peers) {
ivshmem_realize() puts the shared memory region in a container region. Used to be necessary to permit delayed mapping of the shared memory. Now we don't do that anymore, the container is redundant. Drop it. Signed-off-by: Markus Armbruster <armbru@redhat.com> --- hw/misc/ivshmem.c | 44 +++++++++++++++----------------------------- 1 file changed, 15 insertions(+), 29 deletions(-)