> On Mar 29, 2022, at 8:35 AM, Stefan Hajnoczi <[email protected]> wrote:
>
> On Fri, Mar 25, 2022 at 03:19:41PM -0400, Jagannathan Raman wrote:
>> Assign separate address space for each device in the remote processes.
>>
>> Signed-off-by: Elena Ufimtseva <[email protected]>
>> Signed-off-by: John G Johnson <[email protected]>
>> Signed-off-by: Jagannathan Raman <[email protected]>
>> ---
>> include/hw/remote/iommu.h | 18 ++++++++
>> hw/remote/iommu.c | 95 +++++++++++++++++++++++++++++++++++++++
>> MAINTAINERS | 2 +
>> hw/remote/meson.build | 1 +
>> 4 files changed, 116 insertions(+)
>> create mode 100644 include/hw/remote/iommu.h
>> create mode 100644 hw/remote/iommu.c
>>
>> diff --git a/include/hw/remote/iommu.h b/include/hw/remote/iommu.h
>> new file mode 100644
>> index 0000000000..8f850400f1
>> --- /dev/null
>> +++ b/include/hw/remote/iommu.h
>> @@ -0,0 +1,18 @@
>> +/**
>> + * Copyright © 2022 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 REMOTE_IOMMU_H
>> +#define REMOTE_IOMMU_H
>> +
>> +#include "hw/pci/pci_bus.h"
>> +
>> +void remote_configure_iommu(PCIBus *pci_bus);
>> +
>> +void remote_iommu_del_device(PCIDevice *pci_dev);
>> +
>> +#endif
>> diff --git a/hw/remote/iommu.c b/hw/remote/iommu.c
>> new file mode 100644
>> index 0000000000..13f329b45d
>> --- /dev/null
>> +++ b/hw/remote/iommu.c
>> @@ -0,0 +1,95 @@
>> +/**
>> + * IOMMU for remote device
>> + *
>> + * Copyright © 2022 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 "hw/remote/iommu.h"
>> +#include "hw/pci/pci_bus.h"
>> +#include "hw/pci/pci.h"
>> +#include "exec/memory.h"
>> +#include "exec/address-spaces.h"
>> +#include "trace.h"
>> +
>> +struct RemoteIommuElem {
>> + AddressSpace as;
>> + MemoryRegion mr;
>> +};
>> +
>> +struct RemoteIommuTable {
>> + QemuMutex lock;
>> + GHashTable *elem_by_bdf;
>> +} remote_iommu_table;
>> +
>> +#define INT2VOIDP(i) (void *)(uintptr_t)(i)
>> +
>> +static AddressSpace *remote_iommu_find_add_as(PCIBus *pci_bus,
>> + void *opaque, int devfn)
>> +{
>> + struct RemoteIommuTable *iommu_table = opaque;
>> + struct RemoteIommuElem *elem = NULL;
>> + int pci_bdf = PCI_BUILD_BDF(pci_bus_num(pci_bus), devfn);
>> +
>> + elem = g_hash_table_lookup(iommu_table->elem_by_bdf,
>> INT2VOIDP(pci_bdf));
>
> Why is a lock needed around g_hash_table_insert() below but no lock is
> held around g_hash_table_lookup()?
>
> Insertion isn't atomic because lookup and insert are separate operations
> and they are not done under a single lock.
Thanks for the catch! The lock should cover lookup also.
>
>> +
>> + if (!elem) {
>> + g_autofree char *mr_name = g_strdup_printf("vfu-ram-%d", pci_bdf);
>> + g_autofree char *as_name = g_strdup_printf("vfu-as-%d", pci_bdf);
>> +
>> + elem = g_malloc0(sizeof(struct RemoteIommuElem));
>> +
>> + memory_region_init(&elem->mr, NULL, mr_name, UINT64_MAX);
>> + address_space_init(&elem->as, &elem->mr, as_name);
>> +
>> + qemu_mutex_lock(&iommu_table->lock);
>> + g_hash_table_insert(iommu_table->elem_by_bdf, INT2VOIDP(pci_bdf),
>> elem);
>> + qemu_mutex_unlock(&iommu_table->lock);
>> + }
>> +
>> + return &elem->as;
>> +}
>> +
>> +static void remote_iommu_del_elem(gpointer data)
>> +{
>> + struct RemoteIommuElem *elem = data;
>> +
>> + g_assert(elem);
>> +
>> + memory_region_unref(&elem->mr);
>> + address_space_destroy(&elem->as);
>> +
>> + g_free(elem);
>> +}
>> +
>> +void remote_iommu_del_device(PCIDevice *pci_dev)
>> +{
>> + int pci_bdf;
>> +
>> + if (!remote_iommu_table.elem_by_bdf || !pci_dev) {
>> + return;
>> + }
>> +
>> + pci_bdf = PCI_BUILD_BDF(pci_bus_num(pci_get_bus(pci_dev)),
>> pci_dev->devfn);
>> +
>> + qemu_mutex_lock(&remote_iommu_table.lock);
>> + g_hash_table_remove(remote_iommu_table.elem_by_bdf, INT2VOIDP(pci_bdf));
>> + qemu_mutex_unlock(&remote_iommu_table.lock);
>> +}
>> +
>> +void remote_configure_iommu(PCIBus *pci_bus)
>> +{
>> + if (!remote_iommu_table.elem_by_bdf) {
>> + remote_iommu_table.elem_by_bdf =
>> + g_hash_table_new_full(NULL, NULL, NULL, remote_iommu_del_elem);
>> + qemu_mutex_init(&remote_iommu_table.lock);
>> + }
>> +
>> + pci_setup_iommu(pci_bus, remote_iommu_find_add_as, &remote_iommu_table);
>
> Why is remote_iommu_table global? It could be per-PCIBus and indexed by
> just devfn instead of the full BDF.
It’s global because remote_iommu_del_device() needs it for cleanup.
OK, will make it a per bus property.
Thank you!
--
Jag
