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Re: [Qemu-devel] [RFC] virtio: convert to use DMA api
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From: |
Michael S. Tsirkin |
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Subject: |
Re: [Qemu-devel] [RFC] virtio: convert to use DMA api |
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Date: |
Mon, 23 Nov 2015 10:06:00 +0200 |
On Mon, Nov 23, 2015 at 03:41:11PM +0800, Jason Wang wrote:
> Currently, all virtio devices bypass IOMMU completely. This is because
> address_space_memory is assumed and used during DMA emulation. This
> patch converts the virtio core API to use DMA API. This idea is
>
> - introducing a new transport specific helper to query the dma address
> space. (only pci version is implemented).
> - query and use this address space during virtio device guest memory
> accessing
>
> With this virtiodevices will not bypass IOMMU anymore. Little tested with
> intel_iommu=on with virtio guest DMA series posted in
> https://lkml.org/lkml/2015/10/28/64.
>
> TODO:
> - Feature bit for this
This probably implies it should only be implemented
if device supports the modern mode.
Not sure what's the best way to handle transitional
devices.
> - Implement this for all transports
Tested with vhost, and it does not seem to work.
So more TODO:
- make this work with vhost-user and vhost-net.
Also, it seems prudent to add
- make the new behaviour conditional on a new property
> Signed-off-by: Jason Wang <address@hidden>
> ---
> hw/block/virtio-blk.c | 2 +-
> hw/char/virtio-serial-bus.c | 2 +-
> hw/scsi/virtio-scsi.c | 2 +-
> hw/virtio/virtio-pci.c | 9 +++++++++
> hw/virtio/virtio.c | 36 +++++++++++++++++++--------------
> include/hw/virtio/virtio-access.h | 42
> +++++++++++++++++++++++++++++----------
> include/hw/virtio/virtio-bus.h | 1 +
> include/hw/virtio/virtio.h | 2 +-
> 8 files changed, 67 insertions(+), 29 deletions(-)
>
> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> index e70fccf..5499480 100644
> --- a/hw/block/virtio-blk.c
> +++ b/hw/block/virtio-blk.c
> @@ -846,7 +846,7 @@ static int virtio_blk_load_device(VirtIODevice *vdev,
> QEMUFile *f,
> req->next = s->rq;
> s->rq = req;
>
> - virtqueue_map(&req->elem);
> + virtqueue_map(vdev, &req->elem);
> }
>
> return 0;
> diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
> index 497b0af..39e9ed2 100644
> --- a/hw/char/virtio-serial-bus.c
> +++ b/hw/char/virtio-serial-bus.c
> @@ -705,7 +705,7 @@ static int fetch_active_ports_list(QEMUFile *f, int
> version_id,
>
> qemu_get_buffer(f, (unsigned char *)&port->elem,
> sizeof(port->elem));
> - virtqueue_map(&port->elem);
> + virtqueue_map(&s->parent_obj, &port->elem);
>
> /*
> * Port was throttled on source machine. Let's
> diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
> index 7655401..0734d27 100644
> --- a/hw/scsi/virtio-scsi.c
> +++ b/hw/scsi/virtio-scsi.c
> @@ -206,7 +206,7 @@ static void *virtio_scsi_load_request(QEMUFile *f,
> SCSIRequest *sreq)
> req = virtio_scsi_init_req(s, vs->cmd_vqs[n]);
> qemu_get_buffer(f, (unsigned char *)&req->elem, sizeof(req->elem));
>
> - virtqueue_map(&req->elem);
> + virtqueue_map(&vs->parent_obj, &req->elem);
>
> if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICmdReq) + vs->cdb_size,
> sizeof(VirtIOSCSICmdResp) + vs->sense_size) <
> 0) {
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index dd48562..876505d 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1211,6 +1211,14 @@ static int virtio_pci_query_nvectors(DeviceState *d)
> return proxy->nvectors;
> }
>
> +static AddressSpace *virtio_pci_get_dma_as(DeviceState *d)
> +{
> + VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
> + PCIDevice *dev = &proxy->pci_dev;
> +
> + return pci_get_address_space(dev);
> +}
> +
> static int virtio_pci_add_mem_cap(VirtIOPCIProxy *proxy,
> struct virtio_pci_cap *cap)
> {
> @@ -2476,6 +2484,7 @@ static void virtio_pci_bus_class_init(ObjectClass
> *klass, void *data)
> k->device_plugged = virtio_pci_device_plugged;
> k->device_unplugged = virtio_pci_device_unplugged;
> k->query_nvectors = virtio_pci_query_nvectors;
> + k->get_dma_as = virtio_pci_get_dma_as;
> }
>
> static const TypeInfo virtio_pci_bus_info = {
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 1edef59..e09430d 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -21,6 +21,7 @@
> #include "hw/virtio/virtio-bus.h"
> #include "migration/migration.h"
> #include "hw/virtio/virtio-access.h"
> +#include "sysemu/dma.h"
>
> /*
> * The alignment to use between consumer and producer parts of vring.
> @@ -247,6 +248,7 @@ int virtio_queue_empty(VirtQueue *vq)
> static void virtqueue_unmap_sg(VirtQueue *vq, const VirtQueueElement *elem,
> unsigned int len)
> {
> + AddressSpace *dma_as = virtio_get_dma_as(vq->vdev);
> unsigned int offset;
> int i;
>
> @@ -254,17 +256,17 @@ static void virtqueue_unmap_sg(VirtQueue *vq, const
> VirtQueueElement *elem,
> for (i = 0; i < elem->in_num; i++) {
> size_t size = MIN(len - offset, elem->in_sg[i].iov_len);
>
> - cpu_physical_memory_unmap(elem->in_sg[i].iov_base,
> - elem->in_sg[i].iov_len,
> - 1, size);
> + dma_memory_unmap(dma_as, elem->in_sg[i].iov_base,
> elem->in_sg[i].iov_len,
> + DMA_DIRECTION_FROM_DEVICE, size);
>
> offset += size;
> }
>
> for (i = 0; i < elem->out_num; i++)
> - cpu_physical_memory_unmap(elem->out_sg[i].iov_base,
> - elem->out_sg[i].iov_len,
> - 0, elem->out_sg[i].iov_len);
> + dma_memory_unmap(dma_as, elem->out_sg[i].iov_base,
> + elem->out_sg[i].iov_len,
> + DMA_DIRECTION_TO_DEVICE,
> + elem->out_sg[i].iov_len);
> }
>
> void virtqueue_discard(VirtQueue *vq, const VirtQueueElement *elem,
> @@ -448,9 +450,9 @@ int virtqueue_avail_bytes(VirtQueue *vq, unsigned int
> in_bytes,
> return in_bytes <= in_total && out_bytes <= out_total;
> }
>
> -static void virtqueue_map_iovec(struct iovec *sg, hwaddr *addr,
> - unsigned int *num_sg, unsigned int max_size,
> - int is_write)
> +static void virtqueue_map_iovec(VirtIODevice *vdev, struct iovec *sg,
> + hwaddr *addr, unsigned int *num_sg,
> + unsigned int max_size, int is_write)
> {
> unsigned int i;
> hwaddr len;
> @@ -469,7 +471,10 @@ static void virtqueue_map_iovec(struct iovec *sg, hwaddr
> *addr,
>
> for (i = 0; i < *num_sg; i++) {
> len = sg[i].iov_len;
> - sg[i].iov_base = cpu_physical_memory_map(addr[i], &len, is_write);
> + sg[i].iov_base = dma_memory_map(virtio_get_dma_as(vdev),
> + addr[i], &len, is_write ?
> + DMA_DIRECTION_FROM_DEVICE :
> + DMA_DIRECTION_TO_DEVICE);
> if (!sg[i].iov_base) {
> error_report("virtio: error trying to map MMIO memory");
> exit(1);
> @@ -491,13 +496,14 @@ static void virtqueue_map_iovec(struct iovec *sg,
> hwaddr *addr,
> }
> }
>
> -void virtqueue_map(VirtQueueElement *elem)
> +void virtqueue_map(VirtIODevice *vdev, VirtQueueElement *elem)
> {
> - virtqueue_map_iovec(elem->in_sg, elem->in_addr, &elem->in_num,
> + virtqueue_map_iovec(vdev, elem->in_sg, elem->in_addr, &elem->in_num,
> MIN(ARRAY_SIZE(elem->in_sg),
> ARRAY_SIZE(elem->in_addr)),
> 1);
> - virtqueue_map_iovec(elem->out_sg, elem->out_addr, &elem->out_num,
> - MIN(ARRAY_SIZE(elem->out_sg),
> ARRAY_SIZE(elem->out_addr)),
> + virtqueue_map_iovec(vdev, elem->out_sg, elem->out_addr, &elem->out_num,
> + MIN(ARRAY_SIZE(elem->out_sg),
> + ARRAY_SIZE(elem->out_addr)),
> 0);
> }
>
> @@ -562,7 +568,7 @@ int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem)
> } while ((i = virtqueue_next_desc(vdev, desc_pa, i, max)) != max);
>
> /* Now map what we have collected */
> - virtqueue_map(elem);
> + virtqueue_map(vdev, elem);
>
> elem->index = head;
>
> diff --git a/include/hw/virtio/virtio-access.h
> b/include/hw/virtio/virtio-access.h
> index 8aec843..cca7d2a 100644
> --- a/include/hw/virtio/virtio-access.h
> +++ b/include/hw/virtio/virtio-access.h
> @@ -15,8 +15,20 @@
> #ifndef _QEMU_VIRTIO_ACCESS_H
> #define _QEMU_VIRTIO_ACCESS_H
> #include "hw/virtio/virtio.h"
> +#include "hw/virtio/virtio-bus.h"
> #include "exec/address-spaces.h"
>
> +static inline AddressSpace *virtio_get_dma_as(VirtIODevice *vdev)
> +{
> + BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
> + VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
> +
> + if (k->get_dma_as) {
> + return k->get_dma_as(qbus->parent);
> + }
> + return &address_space_memory;
> +}
> +
> static inline bool virtio_access_is_big_endian(VirtIODevice *vdev)
> {
> if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
> @@ -47,45 +59,55 @@ static inline bool
> virtio_legacy_is_cross_endian(VirtIODevice *vdev)
>
> static inline uint16_t virtio_lduw_phys(VirtIODevice *vdev, hwaddr pa)
> {
> + AddressSpace *dma_as = virtio_get_dma_as(vdev);
> +
> if (virtio_access_is_big_endian(vdev)) {
> - return lduw_be_phys(&address_space_memory, pa);
> + return lduw_be_phys(dma_as, pa);
> }
> - return lduw_le_phys(&address_space_memory, pa);
> + return lduw_le_phys(dma_as, pa);
> }
>
> static inline uint32_t virtio_ldl_phys(VirtIODevice *vdev, hwaddr pa)
> {
> + AddressSpace *dma_as = virtio_get_dma_as(vdev);
> +
> if (virtio_access_is_big_endian(vdev)) {
> - return ldl_be_phys(&address_space_memory, pa);
> + return ldl_be_phys(dma_as, pa);
> }
> - return ldl_le_phys(&address_space_memory, pa);
> + return ldl_le_phys(dma_as, pa);
> }
>
> static inline uint64_t virtio_ldq_phys(VirtIODevice *vdev, hwaddr pa)
> {
> + AddressSpace *dma_as = virtio_get_dma_as(vdev);
> +
> if (virtio_access_is_big_endian(vdev)) {
> - return ldq_be_phys(&address_space_memory, pa);
> + return ldq_be_phys(dma_as, pa);
> }
> - return ldq_le_phys(&address_space_memory, pa);
> + return ldq_le_phys(dma_as, pa);
> }
>
> static inline void virtio_stw_phys(VirtIODevice *vdev, hwaddr pa,
> uint16_t value)
> {
> + AddressSpace *dma_as = virtio_get_dma_as(vdev);
> +
> if (virtio_access_is_big_endian(vdev)) {
> - stw_be_phys(&address_space_memory, pa, value);
> + stw_be_phys(dma_as, pa, value);
> } else {
> - stw_le_phys(&address_space_memory, pa, value);
> + stw_le_phys(dma_as, pa, value);
> }
> }
>
> static inline void virtio_stl_phys(VirtIODevice *vdev, hwaddr pa,
> uint32_t value)
> {
> + AddressSpace *dma_as = virtio_get_dma_as(vdev);
> +
> if (virtio_access_is_big_endian(vdev)) {
> - stl_be_phys(&address_space_memory, pa, value);
> + stl_be_phys(dma_as, pa, value);
> } else {
> - stl_le_phys(&address_space_memory, pa, value);
> + stl_le_phys(dma_as, pa, value);
> }
> }
>
> diff --git a/include/hw/virtio/virtio-bus.h b/include/hw/virtio/virtio-bus.h
> index 6c3d4cb..638735e 100644
> --- a/include/hw/virtio/virtio-bus.h
> +++ b/include/hw/virtio/virtio-bus.h
> @@ -71,6 +71,7 @@ typedef struct VirtioBusClass {
> * Note that changing this will break migration for this transport.
> */
> bool has_variable_vring_alignment;
> + AddressSpace *(*get_dma_as)(DeviceState *d);
> } VirtioBusClass;
>
> struct VirtioBusState {
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index 205fadf..7a8ef13 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -151,7 +151,7 @@ void virtqueue_discard(VirtQueue *vq, const
> VirtQueueElement *elem,
> void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
> unsigned int len, unsigned int idx);
>
> -void virtqueue_map(VirtQueueElement *elem);
> +void virtqueue_map(VirtIODevice *vdev, VirtQueueElement *elem);
> int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem);
> int virtqueue_avail_bytes(VirtQueue *vq, unsigned int in_bytes,
> unsigned int out_bytes);
> --
> 2.5.0