Message ID | 1355508045-28120-4-git-send-email-stefanha@redhat.com |
---|---|
State | New |
Headers | show |
On Fri, Dec 14, 2012 at 6:00 PM, Stefan Hajnoczi <stefanha@redhat.com> wrote: > The data plane thread needs to map guest physical addresses to host > pointers. Normally this is done with cpu_physical_memory_map() but the > function assumes the global mutex is held. The data plane thread does > not touch the global mutex and therefore needs a thread-safe memory > mapping mechanism. > > Hostmem registers a MemoryListener similar to how vhost collects and > pushes memory region information into the kernel. There is a > fine-grained lock on the regions list which is held during lookup and > when installing a new regions list. > > When the physical memory map changes the MemoryListener callbacks are > invoked. They build up a new list of memory regions which is finally > installed when the list has been completed. > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > --- > hw/Makefile.objs | 2 +- > hw/dataplane/Makefile.objs | 3 + > hw/dataplane/hostmem.c | 176 +++++++++++++++++++++++++++++++++++++++++++++ > hw/dataplane/hostmem.h | 57 +++++++++++++++ > 4 files changed, 237 insertions(+), 1 deletion(-) > create mode 100644 hw/dataplane/Makefile.objs > create mode 100644 hw/dataplane/hostmem.c > create mode 100644 hw/dataplane/hostmem.h > > diff --git a/hw/Makefile.objs b/hw/Makefile.objs > index d581d8d..cec84bc 100644 > --- a/hw/Makefile.objs > +++ b/hw/Makefile.objs > @@ -1,4 +1,4 @@ > -common-obj-y = usb/ ide/ > +common-obj-y = usb/ ide/ dataplane/ > common-obj-y += loader.o > common-obj-$(CONFIG_VIRTIO) += virtio-console.o > common-obj-$(CONFIG_VIRTIO) += virtio-rng.o > diff --git a/hw/dataplane/Makefile.objs b/hw/dataplane/Makefile.objs > new file mode 100644 > index 0000000..8c8dea1 > --- /dev/null > +++ b/hw/dataplane/Makefile.objs > @@ -0,0 +1,3 @@ > +ifeq ($(CONFIG_VIRTIO), y) > +common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o > +endif > diff --git a/hw/dataplane/hostmem.c b/hw/dataplane/hostmem.c > new file mode 100644 > index 0000000..92f6196 > --- /dev/null > +++ b/hw/dataplane/hostmem.c > @@ -0,0 +1,176 @@ > +/* > + * Thread-safe guest to host memory mapping > + * > + * Copyright 2012 Red Hat, Inc. and/or its affiliates > + * > + * Authors: > + * Stefan Hajnoczi <stefanha@redhat.com> > + * > + * 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 "exec-memory.h" > +#include "hostmem.h" > + > +static int hostmem_lookup_cmp(const void *phys_, const void *region_) > +{ > + hwaddr phys = *(const hwaddr *)phys_; > + const HostmemRegion *region = region_; > + > + if (phys < region->guest_addr) { > + return -1; > + } else if (phys >= region->guest_addr + region->size) { > + return 1; > + } else { > + return 0; > + } > +} > + > +/** > + * Map guest physical address to host pointer > + */ > +void *hostmem_lookup(Hostmem *hostmem, hwaddr phys, hwaddr len, bool is_write) > +{ > + HostmemRegion *region; > + void *host_addr = NULL; > + hwaddr offset_within_region; > + > + qemu_mutex_lock(&hostmem->current_regions_lock); > + region = bsearch(&phys, hostmem->current_regions, > + hostmem->num_current_regions, > + sizeof(hostmem->current_regions[0]), > + hostmem_lookup_cmp); > + if (!region) { > + goto out; > + } > + if (is_write && region->readonly) { > + goto out; > + } > + offset_within_region = phys - region->guest_addr; > + if (len <= region->size - offset_within_region) { > + host_addr = region->host_addr + offset_within_region; > + } > +out: > + qemu_mutex_unlock(&hostmem->current_regions_lock); > + > + return host_addr; > +} > + > +/** > + * Install new regions list > + */ > +static void hostmem_listener_commit(MemoryListener *listener) > +{ > + Hostmem *hostmem = container_of(listener, Hostmem, listener); > + > + qemu_mutex_lock(&hostmem->current_regions_lock); > + g_free(hostmem->current_regions); > + hostmem->current_regions = hostmem->new_regions; > + hostmem->num_current_regions = hostmem->num_new_regions; > + qemu_mutex_unlock(&hostmem->current_regions_lock); > + > + /* Reset new regions list */ > + hostmem->new_regions = NULL; > + hostmem->num_new_regions = 0; > +} > + > +/** > + * Add a MemoryRegionSection to the new regions list > + */ > +static void hostmem_append_new_region(Hostmem *hostmem, > + MemoryRegionSection *section) > +{ > + void *ram_ptr = memory_region_get_ram_ptr(section->mr); > + size_t num = hostmem->num_new_regions; > + size_t new_size = (num + 1) * sizeof(hostmem->new_regions[0]); > + > + hostmem->new_regions = g_realloc(hostmem->new_regions, new_size); > + hostmem->new_regions[num] = (HostmemRegion){ > + .host_addr = ram_ptr + section->offset_within_region, > + .guest_addr = section->offset_within_address_space, > + .size = section->size, > + .readonly = section->readonly, > + }; > + hostmem->num_new_regions++; > +} > + > +static void hostmem_listener_append_region(MemoryListener *listener, > + MemoryRegionSection *section) > +{ > + Hostmem *hostmem = container_of(listener, Hostmem, listener); > + > + /* Ignore non-RAM regions, we may not be able to map them */ > + if (!memory_region_is_ram(section->mr)) { > + return; > + } > + > + /* Ignore regions with dirty logging, we cannot mark them dirty */ > + if (memory_region_is_logging(section->mr)) { > + return; > + } > + > + hostmem_append_new_region(hostmem, section); > +} > + > +/* We don't implement most MemoryListener callbacks, use these nop stubs */ > +static void hostmem_listener_dummy(MemoryListener *listener) > +{ > +} > + > +static void hostmem_listener_section_dummy(MemoryListener *listener, > + MemoryRegionSection *section) > +{ > +} > + > +static void hostmem_listener_eventfd_dummy(MemoryListener *listener, > + MemoryRegionSection *section, > + bool match_data, uint64_t data, > + EventNotifier *e) > +{ > +} > + > +static void hostmem_listener_coalesced_mmio_dummy(MemoryListener *listener, > + MemoryRegionSection *section, > + hwaddr addr, hwaddr len) > +{ > +} > + > +void hostmem_init(Hostmem *hostmem) > +{ > + memset(hostmem, 0, sizeof(*hostmem)); > + > + qemu_mutex_init(&hostmem->current_regions_lock); > + > + hostmem->listener = (MemoryListener){ > + .begin = hostmem_listener_dummy, > + .commit = hostmem_listener_commit, > + .region_add = hostmem_listener_append_region, > + .region_del = hostmem_listener_section_dummy, > + .region_nop = hostmem_listener_append_region, > + .log_start = hostmem_listener_section_dummy, > + .log_stop = hostmem_listener_section_dummy, > + .log_sync = hostmem_listener_section_dummy, > + .log_global_start = hostmem_listener_dummy, > + .log_global_stop = hostmem_listener_dummy, > + .eventfd_add = hostmem_listener_eventfd_dummy, > + .eventfd_del = hostmem_listener_eventfd_dummy, > + .coalesced_mmio_add = hostmem_listener_coalesced_mmio_dummy, > + .coalesced_mmio_del = hostmem_listener_coalesced_mmio_dummy, > + .priority = 10, > + }; > + > + memory_listener_register(&hostmem->listener, &address_space_memory); > + if (hostmem->num_new_regions > 0) { > + hostmem_listener_commit(&hostmem->listener); > + } > +} > + > +void hostmem_finalize(Hostmem *hostmem) > +{ > + memory_listener_unregister(&hostmem->listener); > + g_free(hostmem->new_regions); > + g_free(hostmem->current_regions); > + qemu_mutex_destroy(&hostmem->current_regions_lock); > +} > diff --git a/hw/dataplane/hostmem.h b/hw/dataplane/hostmem.h > new file mode 100644 > index 0000000..6d87841 > --- /dev/null > +++ b/hw/dataplane/hostmem.h > @@ -0,0 +1,57 @@ > +/* > + * Thread-safe guest to host memory mapping > + * > + * Copyright 2012 Red Hat, Inc. and/or its affiliates > + * > + * Authors: > + * Stefan Hajnoczi <stefanha@redhat.com> > + * > + * 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 HOSTMEM_H > +#define HOSTMEM_H > + > +#include "memory.h" > +#include "qemu-thread.h" > + > +typedef struct { > + void *host_addr; > + hwaddr guest_addr; > + uint64_t size; > + bool readonly; > +} HostmemRegion; This should be HostMemRegion. > + > +typedef struct { > + /* The listener is invoked when regions change and a new list of regions is > + * built up completely before they are installed. > + */ > + MemoryListener listener; > + HostmemRegion *new_regions; > + size_t num_new_regions; > + > + /* Current regions are accessed from multiple threads either to lookup > + * addresses or to install a new list of regions. The lock protects the > + * pointer and the regions. > + */ > + QemuMutex current_regions_lock; > + HostmemRegion *current_regions; > + size_t num_current_regions; > +} Hostmem; And this HostMem. > + > +void hostmem_init(Hostmem *hostmem); > +void hostmem_finalize(Hostmem *hostmem); > + > +/** > + * Map a guest physical address to a pointer > + * > + * Note that there is map/unmap mechanism here. The caller must ensure that > + * mapped memory is no longer used across events like hot memory unplug. This > + * can be done with other mechanisms like bdrv_drain_all() that quiesce > + * in-flight I/O. > + */ > +void *hostmem_lookup(Hostmem *hostmem, hwaddr phys, hwaddr len, bool is_write); > + > +#endif /* HOSTMEM_H */ > -- > 1.8.0.2 >
On Fri, Dec 14, 2012 at 9:34 PM, Blue Swirl <blauwirbel@gmail.com> wrote: > On Fri, Dec 14, 2012 at 6:00 PM, Stefan Hajnoczi <stefanha@redhat.com> wrote: >> +typedef struct { >> + void *host_addr; >> + hwaddr guest_addr; >> + uint64_t size; >> + bool readonly; >> +} HostmemRegion; > > This should be HostMemRegion. > >> + >> +typedef struct { >> + /* The listener is invoked when regions change and a new list of regions is >> + * built up completely before they are installed. >> + */ >> + MemoryListener listener; >> + HostmemRegion *new_regions; >> + size_t num_new_regions; >> + >> + /* Current regions are accessed from multiple threads either to lookup >> + * addresses or to install a new list of regions. The lock protects the >> + * pointer and the regions. >> + */ >> + QemuMutex current_regions_lock; >> + HostmemRegion *current_regions; >> + size_t num_current_regions; >> +} Hostmem; > > And this HostMem. Okay, will fix both. Stefan
diff --git a/hw/Makefile.objs b/hw/Makefile.objs index d581d8d..cec84bc 100644 --- a/hw/Makefile.objs +++ b/hw/Makefile.objs @@ -1,4 +1,4 @@ -common-obj-y = usb/ ide/ +common-obj-y = usb/ ide/ dataplane/ common-obj-y += loader.o common-obj-$(CONFIG_VIRTIO) += virtio-console.o common-obj-$(CONFIG_VIRTIO) += virtio-rng.o diff --git a/hw/dataplane/Makefile.objs b/hw/dataplane/Makefile.objs new file mode 100644 index 0000000..8c8dea1 --- /dev/null +++ b/hw/dataplane/Makefile.objs @@ -0,0 +1,3 @@ +ifeq ($(CONFIG_VIRTIO), y) +common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o +endif diff --git a/hw/dataplane/hostmem.c b/hw/dataplane/hostmem.c new file mode 100644 index 0000000..92f6196 --- /dev/null +++ b/hw/dataplane/hostmem.c @@ -0,0 +1,176 @@ +/* + * Thread-safe guest to host memory mapping + * + * Copyright 2012 Red Hat, Inc. and/or its affiliates + * + * Authors: + * Stefan Hajnoczi <stefanha@redhat.com> + * + * 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 "exec-memory.h" +#include "hostmem.h" + +static int hostmem_lookup_cmp(const void *phys_, const void *region_) +{ + hwaddr phys = *(const hwaddr *)phys_; + const HostmemRegion *region = region_; + + if (phys < region->guest_addr) { + return -1; + } else if (phys >= region->guest_addr + region->size) { + return 1; + } else { + return 0; + } +} + +/** + * Map guest physical address to host pointer + */ +void *hostmem_lookup(Hostmem *hostmem, hwaddr phys, hwaddr len, bool is_write) +{ + HostmemRegion *region; + void *host_addr = NULL; + hwaddr offset_within_region; + + qemu_mutex_lock(&hostmem->current_regions_lock); + region = bsearch(&phys, hostmem->current_regions, + hostmem->num_current_regions, + sizeof(hostmem->current_regions[0]), + hostmem_lookup_cmp); + if (!region) { + goto out; + } + if (is_write && region->readonly) { + goto out; + } + offset_within_region = phys - region->guest_addr; + if (len <= region->size - offset_within_region) { + host_addr = region->host_addr + offset_within_region; + } +out: + qemu_mutex_unlock(&hostmem->current_regions_lock); + + return host_addr; +} + +/** + * Install new regions list + */ +static void hostmem_listener_commit(MemoryListener *listener) +{ + Hostmem *hostmem = container_of(listener, Hostmem, listener); + + qemu_mutex_lock(&hostmem->current_regions_lock); + g_free(hostmem->current_regions); + hostmem->current_regions = hostmem->new_regions; + hostmem->num_current_regions = hostmem->num_new_regions; + qemu_mutex_unlock(&hostmem->current_regions_lock); + + /* Reset new regions list */ + hostmem->new_regions = NULL; + hostmem->num_new_regions = 0; +} + +/** + * Add a MemoryRegionSection to the new regions list + */ +static void hostmem_append_new_region(Hostmem *hostmem, + MemoryRegionSection *section) +{ + void *ram_ptr = memory_region_get_ram_ptr(section->mr); + size_t num = hostmem->num_new_regions; + size_t new_size = (num + 1) * sizeof(hostmem->new_regions[0]); + + hostmem->new_regions = g_realloc(hostmem->new_regions, new_size); + hostmem->new_regions[num] = (HostmemRegion){ + .host_addr = ram_ptr + section->offset_within_region, + .guest_addr = section->offset_within_address_space, + .size = section->size, + .readonly = section->readonly, + }; + hostmem->num_new_regions++; +} + +static void hostmem_listener_append_region(MemoryListener *listener, + MemoryRegionSection *section) +{ + Hostmem *hostmem = container_of(listener, Hostmem, listener); + + /* Ignore non-RAM regions, we may not be able to map them */ + if (!memory_region_is_ram(section->mr)) { + return; + } + + /* Ignore regions with dirty logging, we cannot mark them dirty */ + if (memory_region_is_logging(section->mr)) { + return; + } + + hostmem_append_new_region(hostmem, section); +} + +/* We don't implement most MemoryListener callbacks, use these nop stubs */ +static void hostmem_listener_dummy(MemoryListener *listener) +{ +} + +static void hostmem_listener_section_dummy(MemoryListener *listener, + MemoryRegionSection *section) +{ +} + +static void hostmem_listener_eventfd_dummy(MemoryListener *listener, + MemoryRegionSection *section, + bool match_data, uint64_t data, + EventNotifier *e) +{ +} + +static void hostmem_listener_coalesced_mmio_dummy(MemoryListener *listener, + MemoryRegionSection *section, + hwaddr addr, hwaddr len) +{ +} + +void hostmem_init(Hostmem *hostmem) +{ + memset(hostmem, 0, sizeof(*hostmem)); + + qemu_mutex_init(&hostmem->current_regions_lock); + + hostmem->listener = (MemoryListener){ + .begin = hostmem_listener_dummy, + .commit = hostmem_listener_commit, + .region_add = hostmem_listener_append_region, + .region_del = hostmem_listener_section_dummy, + .region_nop = hostmem_listener_append_region, + .log_start = hostmem_listener_section_dummy, + .log_stop = hostmem_listener_section_dummy, + .log_sync = hostmem_listener_section_dummy, + .log_global_start = hostmem_listener_dummy, + .log_global_stop = hostmem_listener_dummy, + .eventfd_add = hostmem_listener_eventfd_dummy, + .eventfd_del = hostmem_listener_eventfd_dummy, + .coalesced_mmio_add = hostmem_listener_coalesced_mmio_dummy, + .coalesced_mmio_del = hostmem_listener_coalesced_mmio_dummy, + .priority = 10, + }; + + memory_listener_register(&hostmem->listener, &address_space_memory); + if (hostmem->num_new_regions > 0) { + hostmem_listener_commit(&hostmem->listener); + } +} + +void hostmem_finalize(Hostmem *hostmem) +{ + memory_listener_unregister(&hostmem->listener); + g_free(hostmem->new_regions); + g_free(hostmem->current_regions); + qemu_mutex_destroy(&hostmem->current_regions_lock); +} diff --git a/hw/dataplane/hostmem.h b/hw/dataplane/hostmem.h new file mode 100644 index 0000000..6d87841 --- /dev/null +++ b/hw/dataplane/hostmem.h @@ -0,0 +1,57 @@ +/* + * Thread-safe guest to host memory mapping + * + * Copyright 2012 Red Hat, Inc. and/or its affiliates + * + * Authors: + * Stefan Hajnoczi <stefanha@redhat.com> + * + * 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 HOSTMEM_H +#define HOSTMEM_H + +#include "memory.h" +#include "qemu-thread.h" + +typedef struct { + void *host_addr; + hwaddr guest_addr; + uint64_t size; + bool readonly; +} HostmemRegion; + +typedef struct { + /* The listener is invoked when regions change and a new list of regions is + * built up completely before they are installed. + */ + MemoryListener listener; + HostmemRegion *new_regions; + size_t num_new_regions; + + /* Current regions are accessed from multiple threads either to lookup + * addresses or to install a new list of regions. The lock protects the + * pointer and the regions. + */ + QemuMutex current_regions_lock; + HostmemRegion *current_regions; + size_t num_current_regions; +} Hostmem; + +void hostmem_init(Hostmem *hostmem); +void hostmem_finalize(Hostmem *hostmem); + +/** + * Map a guest physical address to a pointer + * + * Note that there is map/unmap mechanism here. The caller must ensure that + * mapped memory is no longer used across events like hot memory unplug. This + * can be done with other mechanisms like bdrv_drain_all() that quiesce + * in-flight I/O. + */ +void *hostmem_lookup(Hostmem *hostmem, hwaddr phys, hwaddr len, bool is_write); + +#endif /* HOSTMEM_H */
The data plane thread needs to map guest physical addresses to host pointers. Normally this is done with cpu_physical_memory_map() but the function assumes the global mutex is held. The data plane thread does not touch the global mutex and therefore needs a thread-safe memory mapping mechanism. Hostmem registers a MemoryListener similar to how vhost collects and pushes memory region information into the kernel. There is a fine-grained lock on the regions list which is held during lookup and when installing a new regions list. When the physical memory map changes the MemoryListener callbacks are invoked. They build up a new list of memory regions which is finally installed when the list has been completed. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> --- hw/Makefile.objs | 2 +- hw/dataplane/Makefile.objs | 3 + hw/dataplane/hostmem.c | 176 +++++++++++++++++++++++++++++++++++++++++++++ hw/dataplane/hostmem.h | 57 +++++++++++++++ 4 files changed, 237 insertions(+), 1 deletion(-) create mode 100644 hw/dataplane/Makefile.objs create mode 100644 hw/dataplane/hostmem.c create mode 100644 hw/dataplane/hostmem.h