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virtio-iommu: Add bypass mode support to assigned device 

Currently assigned devices can not work in virtio-iommu bypass mode.
Guest driver fails to probe the device due to DMA failure. And the
reason is because of lacking GPA -> HPA mappings when VM is created.

Add a root container memory region to hold both bypass memory region
and iommu memory region, so the switch between them is supported
just like the implementation in virtual VT-d.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Message-Id: <20220613061010.2674054-2-zhenzhong.duan@intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
master
Zhenzhong Duan 2022-06-13 14:10:08 +08:00 committed by Michael S. Tsirkin
parent b595d6272e
commit 90519b9053
3 changed files with 116 additions and 2 deletions
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1
hw/virtio/trace-events
View File

@ -124,6 +124,7 @@ virtio_iommu_remap(const char *name, uint64_t virt_start, uint64_t virt_end, uin
virtio_iommu_set_page_size_mask(const char *name, uint64_t old, uint64_t new) "mr=%s old_mask=0x%"PRIx64" new_mask=0x%"PRIx64
virtio_iommu_notify_flag_add(const char *name) "add notifier to mr %s"
virtio_iommu_notify_flag_del(const char *name) "del notifier from mr %s"
virtio_iommu_switch_address_space(uint8_t bus, uint8_t slot, uint8_t fn, bool on) "Device %02x:%02x.%x switching address space (iommu enabled=%d)"
# virtio-mem.c
virtio_mem_send_response(uint16_t type) "type=%" PRIu16

115
hw/virtio/virtio-iommu.c
View File

@ -69,6 +69,77 @@ static inline uint16_t virtio_iommu_get_bdf(IOMMUDevice *dev)
return PCI_BUILD_BDF(pci_bus_num(dev->bus), dev->devfn);
}
static bool virtio_iommu_device_bypassed(IOMMUDevice *sdev)
{
uint32_t sid;
bool bypassed;
VirtIOIOMMU *s = sdev->viommu;
VirtIOIOMMUEndpoint *ep;
sid = virtio_iommu_get_bdf(sdev);
qemu_mutex_lock(&s->mutex);
/* need to check bypass before system reset */
if (!s->endpoints) {
bypassed = s->config.bypass;
goto unlock;
}
ep = g_tree_lookup(s->endpoints, GUINT_TO_POINTER(sid));
if (!ep || !ep->domain) {
bypassed = s->config.bypass;
} else {
bypassed = ep->domain->bypass;
}
unlock:
qemu_mutex_unlock(&s->mutex);
return bypassed;
}
/* Return whether the device is using IOMMU translation. */
static bool virtio_iommu_switch_address_space(IOMMUDevice *sdev)
{
bool use_remapping;
assert(sdev);
use_remapping = !virtio_iommu_device_bypassed(sdev);
trace_virtio_iommu_switch_address_space(pci_bus_num(sdev->bus),
PCI_SLOT(sdev->devfn),
PCI_FUNC(sdev->devfn),
use_remapping);
/* Turn off first then on the other */
if (use_remapping) {
memory_region_set_enabled(&sdev->bypass_mr, false);
memory_region_set_enabled(MEMORY_REGION(&sdev->iommu_mr), true);
} else {
memory_region_set_enabled(MEMORY_REGION(&sdev->iommu_mr), false);
memory_region_set_enabled(&sdev->bypass_mr, true);
}
return use_remapping;
}
static void virtio_iommu_switch_address_space_all(VirtIOIOMMU *s)
{
GHashTableIter iter;
IOMMUPciBus *iommu_pci_bus;
int i;
g_hash_table_iter_init(&iter, s->as_by_busptr);
while (g_hash_table_iter_next(&iter, NULL, (void **)&iommu_pci_bus)) {
for (i = 0; i < PCI_DEVFN_MAX; i++) {
if (!iommu_pci_bus->pbdev[i]) {
continue;
}
virtio_iommu_switch_address_space(iommu_pci_bus->pbdev[i]);
}
}
}
/**
* The bus number is used for lookup when SID based operations occur.
* In that case we lazily populate the IOMMUPciBus array from the bus hash
@ -213,6 +284,7 @@ static gboolean virtio_iommu_notify_map_cb(gpointer key, gpointer value,
static void virtio_iommu_detach_endpoint_from_domain(VirtIOIOMMUEndpoint *ep)
{
VirtIOIOMMUDomain *domain = ep->domain;
IOMMUDevice *sdev = container_of(ep->iommu_mr, IOMMUDevice, iommu_mr);
if (!ep->domain) {
return;
@ -221,6 +293,7 @@ static void virtio_iommu_detach_endpoint_from_domain(VirtIOIOMMUEndpoint *ep)
ep->iommu_mr);
QLIST_REMOVE(ep, next);
ep->domain = NULL;
virtio_iommu_switch_address_space(sdev);
}
static VirtIOIOMMUEndpoint *virtio_iommu_get_endpoint(VirtIOIOMMU *s,
@ -323,12 +396,39 @@ static AddressSpace *virtio_iommu_find_add_as(PCIBus *bus, void *opaque,
trace_virtio_iommu_init_iommu_mr(name);
memory_region_init(&sdev->root, OBJECT(s), name, UINT64_MAX);
address_space_init(&sdev->as, &sdev->root, TYPE_VIRTIO_IOMMU);
/*
* Build the IOMMU disabled container with aliases to the
* shared MRs. Note that aliasing to a shared memory region
* could help the memory API to detect same FlatViews so we
* can have devices to share the same FlatView when in bypass
* mode. (either by not configuring virtio-iommu driver or with
* "iommu=pt"). It will greatly reduce the total number of
* FlatViews of the system hence VM runs faster.
*/
memory_region_init_alias(&sdev->bypass_mr, OBJECT(s),
"system", get_system_memory(), 0,
memory_region_size(get_system_memory()));
memory_region_init_iommu(&sdev->iommu_mr, sizeof(sdev->iommu_mr),
TYPE_VIRTIO_IOMMU_MEMORY_REGION,
OBJECT(s), name,
UINT64_MAX);
address_space_init(&sdev->as,
MEMORY_REGION(&sdev->iommu_mr), TYPE_VIRTIO_IOMMU);
/*
* Hook both the containers under the root container, we
* switch between iommu & bypass MRs by enable/disable
* corresponding sub-containers
*/
memory_region_add_subregion_overlap(&sdev->root, 0,
MEMORY_REGION(&sdev->iommu_mr),
0);
memory_region_add_subregion_overlap(&sdev->root, 0,
&sdev->bypass_mr, 0);
virtio_iommu_switch_address_space(sdev);
g_free(name);
}
return &sdev->as;
@ -342,6 +442,7 @@ static int virtio_iommu_attach(VirtIOIOMMU *s,
uint32_t flags = le32_to_cpu(req->flags);
VirtIOIOMMUDomain *domain;
VirtIOIOMMUEndpoint *ep;
IOMMUDevice *sdev;
trace_virtio_iommu_attach(domain_id, ep_id);
@ -375,6 +476,8 @@ static int virtio_iommu_attach(VirtIOIOMMU *s,
QLIST_INSERT_HEAD(&domain->endpoint_list, ep, next);
ep->domain = domain;
sdev = container_of(ep->iommu_mr, IOMMUDevice, iommu_mr);
virtio_iommu_switch_address_space(sdev);
/* Replay domain mappings on the associated memory region */
g_tree_foreach(domain->mappings, virtio_iommu_notify_map_cb,
@ -887,6 +990,7 @@ static void virtio_iommu_set_config(VirtIODevice *vdev,
return;
}
dev_config->bypass = in_config->bypass;
virtio_iommu_switch_address_space_all(dev);
}
trace_virtio_iommu_set_config(in_config->bypass);
@ -1026,6 +1130,8 @@ static void virtio_iommu_system_reset(void *opaque)
* system reset
*/
s->config.bypass = s->boot_bypass;
virtio_iommu_switch_address_space_all(s);
}
static void virtio_iommu_device_realize(DeviceState *dev, Error **errp)
@ -1041,6 +1147,11 @@ static void virtio_iommu_device_realize(DeviceState *dev, Error **errp)
virtio_iommu_handle_command);
s->event_vq = virtio_add_queue(vdev, VIOMMU_DEFAULT_QUEUE_SIZE, NULL);
/*
* config.bypass is needed to get initial address space early, such as
* in vfio realize
*/
s->config.bypass = s->boot_bypass;
s->config.page_size_mask = TARGET_PAGE_MASK;
s->config.input_range.end = UINT64_MAX;
s->config.domain_range.end = UINT32_MAX;

2
include/hw/virtio/virtio-iommu.h
View File

@ -37,6 +37,8 @@ typedef struct IOMMUDevice {
int devfn;
IOMMUMemoryRegion iommu_mr;
AddressSpace as;
MemoryRegion root; /* The root container of the device */
MemoryRegion bypass_mr; /* The alias of shared memory MR */
} IOMMUDevice;
typedef struct IOMMUPciBus {