Hi Akihiko,
On Fri, Feb 25, 2022 at 8:46 PM Akihiko Odaki <akihiko.od...@gmail.com>
wrote:
> On 2022/02/26 2:13, Vladislav Yaroshchuk wrote:
> > Interaction with vmnet.framework in different modes
> > differs only on configuration stage, so we can create
> > common `send`, `receive`, etc. procedures and reuse them.
> >
> > vmnet.framework supports iov, but writing more than
> > one iov into vmnet interface fails with
> > 'VMNET_INVALID_ARGUMENT'. Collecting provided iovs into
> > one and passing it to vmnet works fine. That's the
> > reason why receive_iov() left unimplemented. But it still
> > works with good enough performance having .receive()
> > net/vmnet: implement shared mode (vmnet-shared)
> >
> > Interaction with vmnet.framework in different modes
> > differs only on configuration stage, so we can create
> > common `send`, `receive`, etc. procedures and reuse them.
> >
> > vmnet.framework supports iov, but writing more than
> > one iov into vmnet interface fails with
> > 'VMNET_INVALID_ARGUMENT'. Collecting provided iovs into
> > one and passing it to vmnet works fine. That's the
> > reason why receive_iov() left unimplemented. But it still
> > works with good enough performance having .receive()
> > implemented only.
> >
> > Also, there is no way to unsubscribe from vmnet packages
> > receiving except registering and unregistering event
> > callback or simply drop packages just ignoring and
> > not processing them when related flag is set. Here we do
> > using the second way.
> >
> > Signed-off-by: Phillip Tennen <phil...@axleos.com>
> > Signed-off-by: Vladislav Yaroshchuk <vladislav.yaroshc...@jetbrains.com>
>
> Thank you for persistently working on this.
>
> > ---
> > net/vmnet-common.m | 302 +++++++++++++++++++++++++++++++++++++++++++++
> > net/vmnet-shared.c | 94 +++++++++++++-
> > net/vmnet_int.h | 39 +++++-
> > 3 files changed, 430 insertions(+), 5 deletions(-)
> >
> > diff --git a/net/vmnet-common.m b/net/vmnet-common.m
> > index 56612c72ce..2f70921cae 100644
> > --- a/net/vmnet-common.m
> > +++ b/net/vmnet-common.m
> > @@ -10,6 +10,8 @@
> > */
> >
> > #include "qemu/osdep.h"
> > +#include "qemu/main-loop.h"
> > +#include "qemu/log.h"
> > #include "qapi/qapi-types-net.h"
> > #include "vmnet_int.h"
> > #include "clients.h"
> > @@ -17,4 +19,304 @@
> > #include "qapi/error.h"
> >
> > #include <vmnet/vmnet.h>
> > +#include <dispatch/dispatch.h>
> >
> > +
> > +static inline void vmnet_set_send_bh_scheduled(VmnetCommonState *s,
> > + bool enable)
> > +{
> > + qatomic_set(&s->send_scheduled, enable);
> > +}
> > +
> > +
> > +static inline bool vmnet_is_send_bh_scheduled(VmnetCommonState *s)
> > +{
> > + return qatomic_load_acquire(&s->send_scheduled);
> > +}
> > +
> > +
> > +static inline void vmnet_set_send_enabled(VmnetCommonState *s,
> > + bool enable)
> > +{
> > + if (enable) {
> > + vmnet_interface_set_event_callback(
> > + s->vmnet_if,
> > + VMNET_INTERFACE_PACKETS_AVAILABLE,
> > + s->if_queue,
> > + ^(interface_event_t event_id, xpc_object_t event) {
> > + assert(event_id == VMNET_INTERFACE_PACKETS_AVAILABLE);
> > + /*
> > + * This function is being called from a non qemu
> thread, so
> > + * we only schedule a BH, and do the rest of the io
> completion
> > + * handling from vmnet_send_bh() which runs in a qemu
> context.
> > + *
> > + * Avoid scheduling multiple bottom halves
> > + */
> > + if (!vmnet_is_send_bh_scheduled(s)) {
> > + vmnet_set_send_bh_scheduled(s, true);
>
> It can be interrupted between vmnet_is_send_bh_scheduled and
> vmnet_set_send_bh_scheduled, which leads to data race.
>
>
Sorry, I did not clearly understand what you meant. Since this
callback (block) is submitted on DISPATCH_QUEUE_SERIAL,
only one instance of the callback will be executed at any
moment of time.
https://developer.apple.com/documentation/dispatch/dispatch_queue_serial
Also this is the only place where we schedule a bottom half.
After we set the 'send_scheduled' flag, all the other
callback blocks will do nothing (skip the if block) until
the bottom half is executed and reset 'send_scheduled'.
I don't see any races here :(
Correct me if I'm wrong please.
> > + qemu_bh_schedule(s->send_bh);
> > + }
> > + });
> > + } else {
> > + vmnet_interface_set_event_callback(
> > + s->vmnet_if,
> > + VMNET_INTERFACE_PACKETS_AVAILABLE,
> > + NULL,
> > + NULL);
> > + }
> > +}
> > +
> > +
> > +static void vmnet_send_completed(NetClientState *nc, ssize_t len)
> > +{
> > + VmnetCommonState *s = DO_UPCAST(VmnetCommonState, nc, nc);
> > + vmnet_set_send_enabled(s, true);
> > +}
> > +
> > +
> > +static void vmnet_send_bh(void *opaque)
> > +{
> > + NetClientState *nc = (NetClientState *) opaque;
> > + VmnetCommonState *s = DO_UPCAST(VmnetCommonState, nc, nc);
> > +
> > + struct iovec *iov = s->iov_buf;
> > + struct vmpktdesc *packets = s->packets_buf;
> > + int pkt_cnt;
> > + int i;
> > +
> > + vmnet_return_t status;
> > + ssize_t size;
> > +
> > + /* read as many packets as present */
> > + pkt_cnt = VMNET_PACKETS_LIMIT;
>
> There could be more than VMNET_PACKETS_LIMIT. You may call vmnet_read in
> a loop.
>
> > + for (i = 0; i < pkt_cnt; ++i) {
> > + packets[i].vm_pkt_size = s->max_packet_size;
> > + packets[i].vm_pkt_iovcnt = 1;
> > + packets[i].vm_flags = 0;
> > + }
> > +
> > + status = vmnet_read(s->vmnet_if, packets, &pkt_cnt);
> > + if (status != VMNET_SUCCESS) {
> > + error_printf("vmnet: read failed: %s\n",
> > + vmnet_status_map_str(status));
> > + goto done;
> > + }
> > +
> > + for (i = 0; i < pkt_cnt; ++i) {
> > + size = qemu_send_packet_async(nc,
> > + iov[i].iov_base,
> > + packets[i].vm_pkt_size,
> > + vmnet_send_completed);
> > + if (size == 0) {
> > + vmnet_set_send_enabled(s, false);
> > + goto done;
> > + } else if (size < 0) {
> > + break;
> > + }
>
> goto is not needed here. "break" when size <= 0.
>
> > + }
> > +
> > +done:
> > + vmnet_set_send_bh_scheduled(s, false);
> > +}
> > +
> > +
> > +static void vmnet_bufs_init(VmnetCommonState *s)
> > +{
> > + struct vmpktdesc *packets = s->packets_buf;
> > + struct iovec *iov = s->iov_buf;
> > + int i;
> > +
> > + for (i = 0; i < VMNET_PACKETS_LIMIT; ++i) {
> > + iov[i].iov_len = s->max_packet_size;
> > + iov[i].iov_base = g_malloc0(iov[i].iov_len);
> > + packets[i].vm_pkt_iov = iov + i;
> > + }
> > +}
> > +
> > +
> > +const char *vmnet_status_map_str(vmnet_return_t status)
> > +{
> > + switch (status) {
> > + case VMNET_SUCCESS:
> > + return "success";
> > + case VMNET_FAILURE:
> > + return "general failure (possibly not enough privileges)";
> > + case VMNET_MEM_FAILURE:
> > + return "memory allocation failure";
> > + case VMNET_INVALID_ARGUMENT:
> > + return "invalid argument specified";
> > + case VMNET_SETUP_INCOMPLETE:
> > + return "interface setup is not complete";
> > + case VMNET_INVALID_ACCESS:
> > + return "invalid access, permission denied";
> > + case VMNET_PACKET_TOO_BIG:
> > + return "packet size is larger than MTU";
> > + case VMNET_BUFFER_EXHAUSTED:
> > + return "buffers exhausted in kernel";
> > + case VMNET_TOO_MANY_PACKETS:
> > + return "packet count exceeds limit";
> > +#if defined(MAC_OS_VERSION_11_0) && \
> > + MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_VERSION_11_0
> > + case VMNET_SHARING_SERVICE_BUSY:
> > + return "conflict, sharing service is in use";
> > +#endif
> > + default:
> > + return "unknown vmnet error";
> > + }
> > +}
> > +
> > +
> > +int vmnet_if_create(NetClientState *nc,
> > + xpc_object_t if_desc,
> > + Error **errp)
> > +{
> > + VmnetCommonState *s = DO_UPCAST(VmnetCommonState, nc, nc);;
>
> Duplicate semicolons.
>
> > + dispatch_semaphore_t if_created_sem = dispatch_semaphore_create(0);
>
> if_created_sem leaks.
>
> > + __block vmnet_return_t if_status;
> > +
> > + s->if_queue = dispatch_queue_create(
> > + "org.qemu.vmnet.if_queue",
> > + DISPATCH_QUEUE_SERIAL
> > + );
> > +
> > + xpc_dictionary_set_bool(
> > + if_desc,
> > + vmnet_allocate_mac_address_key,
> > + false
> > + );
> > +#ifdef DEBUG
> > + qemu_log("vmnet.start.interface_desc:\n");
> > + xpc_dictionary_apply(if_desc,
> > + ^bool(const char *k, xpc_object_t v) {
> > + char *desc = xpc_copy_description(v);
> > + qemu_log(" %s=%s\n", k, desc);
> > + free(desc);
> > + return true;
> > + });
> > +#endif /* DEBUG */
> > +
> > + s->vmnet_if = vmnet_start_interface(
> > + if_desc,
> > + s->if_queue,
> > + ^(vmnet_return_t status, xpc_object_t interface_param) {
> > + if_status = status;
> > + if (status != VMNET_SUCCESS || !interface_param) {
> > + dispatch_semaphore_signal(if_created_sem);
> > + return;
> > + }
> > +
> > +#ifdef DEBUG
> > + qemu_log("vmnet.start.interface_param:\n");
> > + xpc_dictionary_apply(interface_param,
> > + ^bool(const char *k, xpc_object_t v) {
> > + char *desc =
> xpc_copy_description(v);
> > + qemu_log(" %s=%s\n", k, desc);
> > + free(desc);
> > + return true;
> > + });
> > +#endif /* DEBUG */
> > +
> > + s->mtu = xpc_dictionary_get_uint64(
> > + interface_param,
> > + vmnet_mtu_key);
> > + s->max_packet_size = xpc_dictionary_get_uint64(
> > + interface_param,
> > + vmnet_max_packet_size_key);
> > +
> > + dispatch_semaphore_signal(if_created_sem);
> > + });
> > +
> > + if (s->vmnet_if == NULL) {
> > + error_setg(errp,
> > + "unable to create interface "
> > + "with requested params");
>
> You don't need line breaks here. Breaking a string into a few would also
> makes it a bit hard to grep.
>
> > + return -1;
>
> s->if_queue leaks.
>
> > + }
> > +
> > + dispatch_semaphore_wait(if_created_sem, DISPATCH_TIME_FOREVER);
> > +
> > + if (if_status != VMNET_SUCCESS) {
> > + error_setg(errp,
> > + "cannot create vmnet interface: %s",
> > + vmnet_status_map_str(if_status));
> > + return -1;
> > + }
> > +
> > + s->send_bh = aio_bh_new(qemu_get_aio_context(), vmnet_send_bh, nc);
> > + vmnet_bufs_init(s);
> > + vmnet_set_send_bh_scheduled(s, false);
> > + vmnet_set_send_enabled(s, true);
> > + return 0;
> > +}
> > +
> > +
> > +ssize_t vmnet_receive_common(NetClientState *nc,
> > + const uint8_t *buf,
> > + size_t size)
> > +{
> > + VmnetCommonState *s = DO_UPCAST(VmnetCommonState, nc, nc);
> > + struct vmpktdesc packet;
> > + struct iovec iov;
> > + int pkt_cnt;
> > + vmnet_return_t if_status;
> > +
> > + if (size > s->max_packet_size) {
> > + warn_report("vmnet: packet is too big, %zu > %llu\n",
>
> Use PRIu64.
>
> > + packet.vm_pkt_size,
> > + s->max_packet_size);
> > + return -1;
> > + }
> > +
> > + iov.iov_base = (char *) buf;
> > + iov.iov_len = size;
> > +
> > + packet.vm_pkt_iovcnt = 1;
> > + packet.vm_flags = 0;
> > + packet.vm_pkt_size = size;
> > + packet.vm_pkt_iov = &iov;
> > + pkt_cnt = 1;
> > +
> > + if_status = vmnet_write(s->vmnet_if, &packet, &pkt_cnt);
> > + if (if_status != VMNET_SUCCESS) {
> > + error_report("vmnet: write error: %s\n",
> > + vmnet_status_map_str(if_status));
>
> Why don't return -1?
>
> > + }
> > +
> > + if (if_status == VMNET_SUCCESS && pkt_cnt) {
> > + return size;
> > + }
> > + return 0;
> > +}
> > +
> > +
> > +void vmnet_cleanup_common(NetClientState *nc)
> > +{
> > + VmnetCommonState *s = DO_UPCAST(VmnetCommonState, nc, nc);;
>
> Duplicate semicolons.
>
> > + dispatch_semaphore_t if_created_sem;
> > +
> > + qemu_purge_queued_packets(nc); > +
> vmnet_set_send_bh_scheduled(s, true);
> > + vmnet_set_send_enabled(s, false);
> > +
> > + if (s->vmnet_if == NULL) {
> > + return;
> > + }
> > +
> > + if_created_sem = dispatch_semaphore_create(0);
> > + vmnet_stop_interface(
> > + s->vmnet_if,
> > + s->if_queue,
> > + ^(vmnet_return_t status) {
> > + assert(status == VMNET_SUCCESS);
> > + dispatch_semaphore_signal(if_created_sem);
> > + });
> > + dispatch_semaphore_wait(if_created_sem, DISPATCH_TIME_FOREVER);
> > +
> > + qemu_bh_delete(s->send_bh);
> > + dispatch_release(if_created_sem);
> > + dispatch_release(s->if_queue);
> > +
> > + for (int i = 0; i < VMNET_PACKETS_LIMIT; ++i) {
> > + g_free(s->iov_buf[i].iov_base);
> > + }
> > +}
> > diff --git a/net/vmnet-shared.c b/net/vmnet-shared.c
> > index f07afaaf21..66f66c034b 100644
> > --- a/net/vmnet-shared.c
> > +++ b/net/vmnet-shared.c
> > @@ -10,16 +10,102 @@
> >
> > #include "qemu/osdep.h"
> > #include "qapi/qapi-types-net.h"
> > +#include "qapi/error.h"
> > #include "vmnet_int.h"
> > #include "clients.h"
> > -#include "qemu/error-report.h"
> > -#include "qapi/error.h"
> >
> > #include <vmnet/vmnet.h>
> >
> > +typedef struct VmnetSharedState {
> > + VmnetCommonState cs;
> > +} VmnetSharedState;
> > +
> > +
> > +static bool validate_options(const Netdev *netdev, Error **errp)
> > +{
> > + const NetdevVmnetSharedOptions *options = &(netdev->u.vmnet_shared);
> > +
> > +#if !defined(MAC_OS_VERSION_11_0) || \
> > + MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_VERSION_11_0
> > + if (options->has_isolated) {
> > + error_setg(errp,
> > + "vmnet-shared.isolated feature is "
> > + "unavailable: outdated vmnet.framework API");
> > + return false;
> > + }
> > +#endif
> > +
> > + if ((options->has_start_address ||
> > + options->has_end_address ||
> > + options->has_subnet_mask) &&
> > + !(options->has_start_address &&
> > + options->has_end_address &&
> > + options->has_subnet_mask)) {
> > + error_setg(errp,
> > + "'start-address', 'end-address', 'subnet-mask' "
> > + "should be provided together"
> > + );
> > + return false;
> > + }
> > +
> > + return true;
> > +}
> > +
> > +static xpc_object_t build_if_desc(const Netdev *netdev)
> > +{
> > + const NetdevVmnetSharedOptions *options = &(netdev->u.vmnet_shared);
> > + xpc_object_t if_desc = xpc_dictionary_create(NULL, NULL, 0);
> > +
> > + xpc_dictionary_set_uint64(
> > + if_desc,
> > + vmnet_operation_mode_key,
> > + VMNET_SHARED_MODE
> > + );
> > +
> > + if (options->has_nat66_prefix) {
> > + xpc_dictionary_set_string(if_desc,
> > + vmnet_nat66_prefix_key,
> > + options->nat66_prefix);
> > + }
> > +
> > + if (options->has_start_address) {
> > + xpc_dictionary_set_string(if_desc,
> > + vmnet_start_address_key,
> > + options->start_address);
> > + xpc_dictionary_set_string(if_desc,
> > + vmnet_end_address_key,
> > + options->end_address);
> > + xpc_dictionary_set_string(if_desc,
> > + vmnet_subnet_mask_key,
> > + options->subnet_mask);
> > + }
> > +
> > +#if defined(MAC_OS_VERSION_11_0) && \
> > + MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_VERSION_11_0
> > + xpc_dictionary_set_bool(
> > + if_desc,
> > + vmnet_enable_isolation_key,
> > + options->isolated
> > + );
> > +#endif
> > +
> > + return if_desc;
> > +}
> > +
> > +static NetClientInfo net_vmnet_shared_info = {
> > + .type = NET_CLIENT_DRIVER_VMNET_SHARED,
> > + .size = sizeof(VmnetSharedState),
> > + .receive = vmnet_receive_common,
> > + .cleanup = vmnet_cleanup_common,
> > +};
> > +
> > int net_init_vmnet_shared(const Netdev *netdev, const char *name,
> > NetClientState *peer, Error **errp)
> > {
> > - error_setg(errp, "vmnet-shared is not implemented yet");
> > - return -1;
> > + NetClientState *nc = qemu_new_net_client(&net_vmnet_shared_info,
> > + peer, "vmnet-shared",
> name);
> > + if (!validate_options(netdev, errp)) {
> > + g_assert_not_reached();
>
> g_assert_not_reached is for debugging purpose and may be dropped
> depending on the build option.
>
> > + }
> > + return vmnet_if_create(nc, build_if_desc(netdev), errp);
> > }
> > diff --git a/net/vmnet_int.h b/net/vmnet_int.h
> > index aac4d5af64..acfe3a88c0 100644
> > --- a/net/vmnet_int.h
> > +++ b/net/vmnet_int.h
> > @@ -15,11 +15,48 @@
> > #include "clients.h"
> >
> > #include <vmnet/vmnet.h>
> > +#include <dispatch/dispatch.h>
> > +
> > +/**
> > + * From vmnet.framework documentation
> > + *
> > + * Each read/write call allows up to 200 packets to be
> > + * read or written for a maximum of 256KB.
> > + *
> > + * Each packet written should be a complete
> > + * ethernet frame.
> > + *
> > + * https://developer.apple.com/documentation/vmnet
> > + */
> > +#define VMNET_PACKETS_LIMIT 200
> >
> > typedef struct VmnetCommonState {
> > - NetClientState nc;
> > + NetClientState nc;
> > + interface_ref vmnet_if;
> > +
> > + bool send_scheduled;
> >
> > + uint64_t mtu;
> > + uint64_t max_packet_size;
> > +
> > + struct vmpktdesc packets_buf[VMNET_PACKETS_LIMIT];
> > + struct iovec iov_buf[VMNET_PACKETS_LIMIT];
> > +
> > + dispatch_queue_t if_queue;
> > +
> > + QEMUBH *send_bh;
> > } VmnetCommonState;
> >
> > +const char *vmnet_status_map_str(vmnet_return_t status);
> > +
> > +int vmnet_if_create(NetClientState *nc,
> > + xpc_object_t if_desc,
> > + Error **errp);
> > +
> > +ssize_t vmnet_receive_common(NetClientState *nc,
> > + const uint8_t *buf,
> > + size_t size);
> > +
> > +void vmnet_cleanup_common(NetClientState *nc);
> >
> > #endif /* VMNET_INT_H */
>
>
Other issues will be fixed and submitted later,
thank you!
Regards,
Vladislav Yaroshchuk
