> On Dec 8, 2020, at 8:57 AM, Marc-André Lureau <marcandre.lur...@gmail.com>
> wrote:
>
> Hi
>
> On Wed, Dec 2, 2020 at 12:23 AM Jagannathan Raman <jag.ra...@oracle.com>
> wrote:
> Add memory-listener object which is used to keep the view of the RAM
> in sync between QEMU and remote process.
> A MemoryListener is registered for system-memory AddressSpace. The
> listener sends SYNC_SYSMEM message to the remote process when memory
> listener commits the changes to memory, the remote process receives
> the message and processes it in the handler for SYNC_SYSMEM message.
>
> Signed-off-by: Jagannathan Raman <jag.ra...@oracle.com>
> Signed-off-by: John G Johnson <john.g.john...@oracle.com>
> Signed-off-by: Elena Ufimtseva <elena.ufimts...@oracle.com>
> Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
> ---
> include/hw/remote/memory-sync.h | 27 ++++++
> include/hw/remote/proxy.h | 2 +
> hw/remote/memory-sync.c | 210
> ++++++++++++++++++++++++++++++++++++++++
> hw/remote/message.c | 5 +
> hw/remote/proxy.c | 6 ++
> MAINTAINERS | 2 +
> hw/remote/meson.build | 1 +
> 7 files changed, 253 insertions(+)
> create mode 100644 include/hw/remote/memory-sync.h
> create mode 100644 hw/remote/memory-sync.c
>
> diff --git a/include/hw/remote/memory-sync.h b/include/hw/remote/memory-sync.h
> new file mode 100644
> index 0000000..785f76a
> --- /dev/null
> +++ b/include/hw/remote/memory-sync.h
> @@ -0,0 +1,27 @@
> +/*
> + * Copyright © 2018, 2020 Oracle and/or its affiliates.
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#ifndef MEMORY_SYNC_H
> +#define MEMORY_SYNC_H
> +
> +#include "exec/memory.h"
> +#include "io/channel.h"
> +
> +typedef struct RemoteMemSync {
> + MemoryListener listener;
> +
> + int n_mr_sections;
> + MemoryRegionSection *mr_sections;
> +
> + QIOChannel *ioc;
> +} RemoteMemSync;
> +
> +void configure_memory_sync(RemoteMemSync *sync, QIOChannel *ioc);
> +void deconfigure_memory_sync(RemoteMemSync *sync);
>
> RemoteMemSync vs MemorySync, and function with _memory_sync suffixes...
> Naming things is hard, but trying to be consistent generally helps.
>
> My understanding is that this is a proxy-dev helper to handle memory
> listening and sending SYNC_SYSMEM.
>
> I would thus suggest naming it ProxyMemoryListener. It could eventually be
> folded in proxy.c
>
> Please try to be consistent with header naming, structure naming, type,
> functions and enum prefixes etc.
>
> proxy_memory_listener isn't that long imho.
>
> +
> +#endif
> diff --git a/include/hw/remote/proxy.h b/include/hw/remote/proxy.h
> index e29c61b..a687b7d 100644
> --- a/include/hw/remote/proxy.h
> +++ b/include/hw/remote/proxy.h
> @@ -11,6 +11,7 @@
>
> #include "hw/pci/pci.h"
> #include "io/channel.h"
> +#include "hw/remote/memory-sync.h"
>
> #define TYPE_PCI_PROXY_DEV "x-pci-proxy-dev"
>
> @@ -40,6 +41,7 @@ struct PCIProxyDev {
> QemuMutex io_mutex;
> QIOChannel *ioc;
> Error *migration_blocker;
> + RemoteMemSync sync;
> ProxyMemoryRegion region[PCI_NUM_REGIONS];
> };
>
> diff --git a/hw/remote/memory-sync.c b/hw/remote/memory-sync.c
> new file mode 100644
> index 0000000..2365e69
> --- /dev/null
> +++ b/hw/remote/memory-sync.c
> @@ -0,0 +1,210 @@
> +/*
> + * Copyright © 2018, 2020 Oracle and/or its affiliates.
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu-common.h"
> +
> +#include "qemu/compiler.h"
> +#include "qemu/int128.h"
> +#include "qemu/range.h"
> +#include "exec/memory.h"
> +#include "exec/cpu-common.h"
> +#include "cpu.h"
> +#include "exec/ram_addr.h"
> +#include "exec/address-spaces.h"
> +#include "hw/remote/mpqemu-link.h"
> +#include "hw/remote/memory-sync.h"
> +
> +static void proxy_ml_begin(MemoryListener *listener)
>
> I suggest to rename begin -> reset
>
> +{
> + RemoteMemSync *sync = container_of(listener, RemoteMemSync, listener);
> + int mrs;
> +
> + for (mrs = 0; mrs < sync->n_mr_sections; mrs++) {
> + memory_region_unref(sync->mr_sections[mrs].mr);
> + }
> +
> + g_free(sync->mr_sections);
> + sync->mr_sections = NULL;
> + sync->n_mr_sections = 0;
> +}
> +
> +static int get_fd_from_hostaddr(uint64_t host, ram_addr_t *offset)
>
> This function is very similar to vhost_user_get_mr_data(). That suggests we
> could factor the code.
>
> Perhaps a new memory_region_from_host_full(), or extend
> memory_region_from_host() with an extra optional "int *fd" argument.
>
> +{
> + MemoryRegion *mr;
> + ram_addr_t off;
> +
> + /**
> + * Assumes that the host address is a valid address as it's
> + * coming from the MemoryListener system. In the case host
> + * address is not valid, the following call would return
> + * the default subregion of "system_memory" region, and
> + * not NULL. So it's not possible to check for NULL here.
> + */
> + mr = memory_region_from_host((void *)(uintptr_t)host, &off);
> +
> + if (offset) {
> + *offset = off;
> + }
> +
> + return memory_region_get_fd(mr);
> +}
> +
> +static bool proxy_mrs_can_merge(uint64_t host, uint64_t prev_host, size_t
> size)
> +{
>
> This seems similar to vhost_user_can_merge().
>
> + bool merge;
> + int fd1, fd2;
> +
> + fd1 = get_fd_from_hostaddr(host, NULL);
> +
> + fd2 = get_fd_from_hostaddr(prev_host, NULL);
> +
> + merge = (fd1 == fd2);
>
> This could be written in a simpler manner, ex:
>
> if (get_fd_from_hostaddr(host, NULL) != get_fd_from_hostaddr(prev_host, NULL))
> return false
>
> +
> + merge &= ((prev_host + size) == host);
>
> That check could be done early on before doing the more expensive
> memory_region_from_host() calls
>
> +
> + return merge;
> +}
> +
> +static bool try_merge(RemoteMemSync *sync, MemoryRegionSection *section)
> +{
> + uint64_t mrs_size, mrs_gpa, mrs_page;
> + MemoryRegionSection *prev_sec;
> + bool merged = false;
> + uintptr_t mrs_host;
> + RAMBlock *mrs_rb;
> +
> + if (!sync->n_mr_sections) {
> + return false;
> + }
> +
> + mrs_rb = section->mr->ram_block;
> + mrs_page = (uint64_t)qemu_ram_pagesize(mrs_rb);
> + mrs_size = int128_get64(section->size);
> + mrs_gpa = section->offset_within_address_space;
> + mrs_host = (uintptr_t)memory_region_get_ram_ptr(section->mr) +
> + section->offset_within_region;
> +
> + if (get_fd_from_hostaddr(mrs_host, NULL) < 0) {
> + return true;
> + }
> +
> + mrs_host = mrs_host & ~(mrs_page - 1);
> + mrs_gpa = mrs_gpa & ~(mrs_page - 1);
> + mrs_size = ROUND_UP(mrs_size, mrs_page);
> +
> + prev_sec = sync->mr_sections + (sync->n_mr_sections - 1);
> + uint64_t prev_gpa_start = prev_sec->offset_within_address_space;
> + uint64_t prev_size = int128_get64(prev_sec->size);
> + uint64_t prev_gpa_end = range_get_last(prev_gpa_start, prev_size);
> + uint64_t prev_host_start =
> + (uintptr_t)memory_region_get_ram_ptr(prev_sec->mr) +
> + prev_sec->offset_within_region;
> + uint64_t prev_host_end = range_get_last(prev_host_start, prev_size);
> +
> + if (mrs_gpa <= (prev_gpa_end + 1)) {
> + g_assert(mrs_gpa > prev_gpa_start);
> +
> + if ((section->mr == prev_sec->mr) &&
> + proxy_mrs_can_merge(mrs_host, prev_host_start,
> + (mrs_gpa - prev_gpa_start))) {
> + uint64_t max_end = MAX(prev_host_end, mrs_host + mrs_size);
> + merged = true;
> + prev_sec->offset_within_address_space =
> + MIN(prev_gpa_start, mrs_gpa);
> + prev_sec->offset_within_region =
> + MIN(prev_host_start, mrs_host) -
> + (uintptr_t)memory_region_get_ram_ptr(prev_sec->mr);
> + prev_sec->size = int128_make64(max_end - MIN(prev_host_start,
> + mrs_host));
> + }
> + }
> +
> + return merged;
> +}
> +
> +static void proxy_ml_region_addnop(MemoryListener *listener,
> + MemoryRegionSection *section)
> +{
> + RemoteMemSync *sync = container_of(listener, RemoteMemSync, listener);
> +
> + if (!(memory_region_is_ram(section->mr) &&
> + !memory_region_is_rom(section->mr))) {
> + return;
>
> A bit clearer in vhost.c:
> if (memory_region_is_ram(mr) && !memory_region_is_rom(mr)) {
>
> + }
> +
> + if (try_merge(sync, section)) {
> + return;
> + }
> +
> + ++sync->n_mr_sections;
> + sync->mr_sections = g_renew(MemoryRegionSection, sync->mr_sections,
> + sync->n_mr_sections);
> + sync->mr_sections[sync->n_mr_sections - 1] = *section;
> + sync->mr_sections[sync->n_mr_sections - 1].fv = NULL;
> + memory_region_ref(section->mr);
> +}
> +
> +static void proxy_ml_commit(MemoryListener *listener)
> +{
> + RemoteMemSync *sync = container_of(listener, RemoteMemSync, listener);
> + MPQemuMsg msg;
> + MemoryRegionSection *section;
> + ram_addr_t offset;
> + uintptr_t host_addr;
> + int region;
> + Error *local_err = NULL;
> +
> + memset(&msg, 0, sizeof(MPQemuMsg));
> +
> + msg.cmd = SYNC_SYSMEM;
> + msg.num_fds = sync->n_mr_sections;
> + msg.size = sizeof(SyncSysmemMsg);
> + if (msg.num_fds > REMOTE_MAX_FDS) {
> + error_report("Number of fds is more than %d", REMOTE_MAX_FDS);
> + return;
> + }
> +
> + for (region = 0; region < sync->n_mr_sections; region++) {
> + section = &sync->mr_sections[region];
> + msg.data.sync_sysmem.gpas[region] =
> + section->offset_within_address_space;
> + msg.data.sync_sysmem.sizes[region] = int128_get64(section->size);
> + host_addr = (uintptr_t)memory_region_get_ram_ptr(section->mr) +
> + section->offset_within_region;
> + msg.fds[region] = get_fd_from_hostaddr(host_addr, &offset);
> + msg.data.sync_sysmem.offsets[region] = offset;
> + }
> + mpqemu_msg_send(&msg, sync->ioc, &local_err);
> + if (local_err) {
> + error_report("Error in sending command %d", msg.cmd);
> + }
> +}
>
> That whole complex code above duplicates much of the logic in vhost.c. Can we
> try to factorize it instead?
Hi Marc-Andre,
Thank you for sharing your feedback!
Would it be alright if we addressed this item alone in a separate patch in the
future? Since
this refactoring affects vhost code, we’re wondering it would be better to
address it in a
future patch to help with any regression analysis in the future.
Thank you!
—
Jag
>
> +
> +void deconfigure_memory_sync(RemoteMemSync *sync)
> +{
> + memory_listener_unregister(&sync->listener);
> +
> + proxy_ml_begin(&sync->listener);
> +}
> +
> +void configure_memory_sync(RemoteMemSync *sync, QIOChannel *ioc)
> +{
> + sync->n_mr_sections = 0;
> + sync->mr_sections = NULL;
> +
> + sync->ioc = ioc;
> +
> + sync->listener.begin = proxy_ml_begin;
> + sync->listener.commit = proxy_ml_commit;
> + sync->listener.region_add = proxy_ml_region_addnop;
> + sync->listener.region_nop = proxy_ml_region_addnop;
> + sync->listener.priority = 10;
> +
> + memory_listener_register(&sync->listener, &address_space_memory);
> +}
> diff --git a/hw/remote/message.c b/hw/remote/message.c
> index 0f3e38a..454fd2d 100644
> --- a/hw/remote/message.c
> +++ b/hw/remote/message.c
> @@ -17,6 +17,7 @@
> #include "sysemu/runstate.h"
> #include "hw/pci/pci.h"
> #include "exec/memattrs.h"
> +#include "hw/remote/memory.h"
>
> static void process_config_write(QIOChannel *ioc, PCIDevice *dev,
> MPQemuMsg *msg);
> @@ -64,6 +65,10 @@ void coroutine_fn mpqemu_remote_msg_loop_co(void *data)
> case BAR_READ:
> process_bar_read(com->ioc, &msg, &local_err);
> break;
> + case SYNC_SYSMEM:
> + remote_sysmem_reconfig(&msg, &local_err);
> + break;
> +
> default:
> error_setg(&local_err,
> "Unknown command (%d) received for device %s
> (pid=%d)",
> diff --git a/hw/remote/proxy.c b/hw/remote/proxy.c
> index 039347d..0f2d1aa 100644
> --- a/hw/remote/proxy.c
> +++ b/hw/remote/proxy.c
> @@ -18,6 +18,8 @@
> #include "migration/blocker.h"
> #include "hw/remote/mpqemu-link.h"
> #include "qemu/error-report.h"
> +#include "hw/remote/memory-sync.h"
> +#include "qom/object.h"
>
> static void proxy_set_socket(PCIProxyDev *pdev, int fd, Error **errp)
> {
> @@ -58,6 +60,8 @@ static void pci_proxy_dev_realize(PCIDevice *device, Error
> **errp)
>
> qemu_mutex_init(&dev->io_mutex);
> qio_channel_set_blocking(dev->ioc, true, NULL);
> +
> + configure_memory_sync(&dev->sync, dev->ioc);
> }
>
> static void pci_proxy_dev_exit(PCIDevice *pdev)
> @@ -69,6 +73,8 @@ static void pci_proxy_dev_exit(PCIDevice *pdev)
> migrate_del_blocker(dev->migration_blocker);
>
> error_free(dev->migration_blocker);
> +
> + deconfigure_memory_sync(&dev->sync);
> }
>
> static int config_op_send(PCIProxyDev *pdev, uint32_t addr, uint32_t *val,
> diff --git a/MAINTAINERS b/MAINTAINERS
> index ebd1d1d..5d78b78 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3150,6 +3150,8 @@ F: include/hw/remote/memory.h
> F: hw/remote/memory.c
> F: hw/remote/proxy.c
> F: include/hw/remote/proxy.h
> +F: hw/remote/memory-sync.c
> +F: include/hw/remote/memory-sync.h
>
> Build and test automation
> -------------------------
> diff --git a/hw/remote/meson.build b/hw/remote/meson.build
> index 569cd20..7d434a5 100644
> --- a/hw/remote/meson.build
> +++ b/hw/remote/meson.build
> @@ -7,5 +7,6 @@ remote_ss.add(when: 'CONFIG_MULTIPROCESS', if_true:
> files('remote-obj.c'))
> remote_ss.add(when: 'CONFIG_MULTIPROCESS', if_true: files('proxy.c'))
>
> specific_ss.add(when: 'CONFIG_MULTIPROCESS', if_true: files('memory.c'))
> +specific_ss.add(when: 'CONFIG_MULTIPROCESS', if_true: files('memory-sync.c'))
>
> softmmu_ss.add_all(when: 'CONFIG_MULTIPROCESS', if_true: remote_ss)
> --
> 1.8.3.1
>
>
>
> --
> Marc-André Lureau
