[SLOF] [PATCH slof v3 4/4] virtio: Enable IOMMU
Michael Roth
mdroth at linux.vnet.ibm.com
Fri Nov 22 11:09:56 AEDT 2019
Quoting Alexey Kardashevskiy (2019-11-20 17:58:01)
> When QEMU is started with iommu_platform=on, the guest driver must accept
> it or the device will fail.
>
> This enables IOMMU support for virtio-net, -scsi, -block, -serial, -9p
> devices. -serial and -9p are only compile tested though.
>
> For virtio-net we map all RX buffers once and TX when xmit() is called
> and unmap older pages when we are about to reuse the VQ descriptor.
> As all other devices are synchronous, we unmap IOMMU pages right after
> completion of a transaction.
>
> This depends on QEMU's:
> https://patchwork.ozlabs.org/patch/1194067/
>
> Copied-bits-and-pieces-from: Michael Roth <mdroth at linux.vnet.ibm.com>
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> ---
> Changes:
> v2:
> * added Mike's fs/dma-instance-function.fs
> * total rework
> ---
> board-qemu/slof/Makefile | 1 +
> lib/libvirtio/virtio.h | 5 ++
> lib/libvirtio/virtio-9p.c | 4 ++
> lib/libvirtio/virtio-blk.c | 4 ++
> lib/libvirtio/virtio-net.c | 5 +-
> lib/libvirtio/virtio-scsi.c | 5 ++
> lib/libvirtio/virtio-serial.c | 12 +++--
> lib/libvirtio/virtio.c | 82 +++++++++++++++++++++++++++++++-
> board-qemu/slof/OF.fs | 3 ++
> slof/fs/dma-instance-function.fs | 28 +++++++++++
> 10 files changed, 143 insertions(+), 6 deletions(-)
> create mode 100644 slof/fs/dma-instance-function.fs
>
> diff --git a/board-qemu/slof/Makefile b/board-qemu/slof/Makefile
> index 2263e751bde9..d7ed2d7a6f18 100644
> --- a/board-qemu/slof/Makefile
> +++ b/board-qemu/slof/Makefile
> @@ -99,6 +99,7 @@ OF_FFS_FILES = \
> $(SLOFCMNDIR)/fs/graphics.fs \
> $(SLOFCMNDIR)/fs/generic-disk.fs \
> $(SLOFCMNDIR)/fs/dma-function.fs \
> + $(SLOFCMNDIR)/fs/dma-instance-function.fs \
> $(SLOFCMNDIR)/fs/pci-device.fs \
> $(SLOFCMNDIR)/fs/pci-bridge.fs \
> $(SLOFCMNDIR)/fs/pci-properties.fs \
> diff --git a/lib/libvirtio/virtio.h b/lib/libvirtio/virtio.h
> index 4927a97f9f5f..250120b3112b 100644
> --- a/lib/libvirtio/virtio.h
> +++ b/lib/libvirtio/virtio.h
> @@ -29,6 +29,7 @@
> #define VIRTIO_F_RING_INDIRECT_DESC BIT(28)
> #define VIRTIO_F_RING_EVENT_IDX BIT(29)
> #define VIRTIO_F_VERSION_1 BIT(32)
> +#define VIRTIO_F_IOMMU_PLATFORM BIT(33)
>
> #define VIRTIO_TIMEOUT 5000 /* 5 sec timeout */
>
> @@ -84,6 +85,8 @@ struct vqs {
> struct vring_desc *desc;
> struct vring_avail *avail;
> struct vring_used *used;
> + void **desc_gpas; /* to get gpa from desc->addr (which is ioba) */
> + uint64_t bus_desc;
> };
>
> struct virtio_device {
> @@ -109,6 +112,8 @@ extern struct vring_used *virtio_get_vring_used(struct virtio_device *dev, int q
> extern void virtio_fill_desc(struct vqs *vq, int id, uint64_t features,
> uint64_t addr, uint32_t len,
> uint16_t flags, uint16_t next);
> +extern void virtio_free_desc(struct vqs *vq, int id, uint64_t features);
> +void *virtio_desc_addr(struct virtio_device *vdev, int queue, int id);
> extern struct vqs *virtio_queue_init_vq(struct virtio_device *dev, unsigned int id);
> extern void virtio_queue_term_vq(struct virtio_device *dev, struct vqs *vq, unsigned int id);
>
> diff --git a/lib/libvirtio/virtio-9p.c b/lib/libvirtio/virtio-9p.c
> index 426069fe9509..76078612b06e 100644
> --- a/lib/libvirtio/virtio-9p.c
> +++ b/lib/libvirtio/virtio-9p.c
> @@ -129,6 +129,10 @@ static int virtio_9p_transact(void *opaque, uint8_t *tx, int tx_size, uint8_t *r
> // do something better
> mb();
> }
> +
> + virtio_free_desc(vq, id, dev->features);
> + virtio_free_desc(vq, id + 1, dev->features);
> +
> if (i == 0) {
> return -1;
> }
> diff --git a/lib/libvirtio/virtio-blk.c b/lib/libvirtio/virtio-blk.c
> index a0dadbb0d6a8..0363038e559d 100644
> --- a/lib/libvirtio/virtio-blk.c
> +++ b/lib/libvirtio/virtio-blk.c
> @@ -195,6 +195,10 @@ virtioblk_transfer(struct virtio_device *dev, char *buf, uint64_t blocknum,
> break;
> }
>
> + virtio_free_desc(vq, id, dev->features);
> + virtio_free_desc(vq, id + 1, dev->features);
> + virtio_free_desc(vq, id + 2, dev->features);
> +
> if (status == 0)
> return cnt;
>
> diff --git a/lib/libvirtio/virtio-net.c b/lib/libvirtio/virtio-net.c
> index ae67883020ef..5a0d19088527 100644
> --- a/lib/libvirtio/virtio-net.c
> +++ b/lib/libvirtio/virtio-net.c
> @@ -255,6 +255,9 @@ static int virtionet_xmit(struct virtio_net *vnet, char *buf, int len)
> idx = virtio_modern16_to_cpu(vdev, vq_tx->avail->idx);
> id = (idx * 2) % vq_tx->size;
>
> + virtio_free_desc(vq_tx, id, vdev->features);
> + virtio_free_desc(vq_tx, id + 1, vdev->features);
> +
> /* Set up virtqueue descriptor for header */
> virtio_fill_desc(vq_tx, id, vdev->features, (uint64_t)nethdr,
> net_hdr_size, VRING_DESC_F_NEXT, id + 1);
> @@ -317,7 +320,7 @@ static int virtionet_receive(struct virtio_net *vnet, char *buf, int maxlen)
> #endif
>
> /* Copy data to destination buffer */
> - memcpy(buf, (void *)virtio_modern64_to_cpu(vdev, vq_rx->desc[id].addr), len);
> + memcpy(buf, virtio_desc_addr(vdev, VQ_RX, id), len);
>
> /* Move indices to next entries */
> last_rx_idx = last_rx_idx + 1;
> diff --git a/lib/libvirtio/virtio-scsi.c b/lib/libvirtio/virtio-scsi.c
> index 251661e8d466..44573d10e24c 100644
> --- a/lib/libvirtio/virtio-scsi.c
> +++ b/lib/libvirtio/virtio-scsi.c
> @@ -81,6 +81,11 @@ int virtioscsi_send(struct virtio_device *dev,
> break;
> }
>
> + virtio_free_desc(vq, id, dev->features);
> + virtio_free_desc(vq, id + 1, dev->features);
> + if (!(buf == NULL || buf_len == 0))
> + virtio_free_desc(vq, id + 2, dev->features);
> +
> return 0;
> }
>
> diff --git a/lib/libvirtio/virtio-serial.c b/lib/libvirtio/virtio-serial.c
> index 78ab0e25d7db..66fbfe8b6cc6 100644
> --- a/lib/libvirtio/virtio-serial.c
> +++ b/lib/libvirtio/virtio-serial.c
> @@ -108,7 +108,7 @@ void virtio_serial_shutdown(struct virtio_device *dev)
>
> int virtio_serial_putchar(struct virtio_device *dev, char c)
> {
> - int id;
> + int id, ret;
> uint32_t vq_size, time;
> volatile uint16_t *current_used_idx;
> uint16_t last_used_idx, avail_idx;
> @@ -135,17 +135,21 @@ int virtio_serial_putchar(struct virtio_device *dev, char c)
> virtio_queue_notify(dev, TX_Q);
>
> /* Wait for host to consume the descriptor */
> + ret = 1;
> time = SLOF_GetTimer() + VIRTIO_TIMEOUT;
> while (*current_used_idx == last_used_idx) {
> // do something better
> mb();
> if (time < SLOF_GetTimer()) {
> printf("virtio_serial_putchar failed! \n");
> - return 0;
> + ret = 0;
> + break;
> }
> }
>
> - return 1;
> + virtio_free_desc(vq, id, dev->features);
> +
> + return ret;
> }
>
> char virtio_serial_getchar(struct virtio_device *dev)
> @@ -165,7 +169,7 @@ char virtio_serial_getchar(struct virtio_device *dev)
> % vq_rx->size;
>
> /* Copy data to destination buffer */
> - memcpy(buf, (void *)virtio_modern64_to_cpu(dev, vq_rx->desc[id - 1].addr), RX_ELEM_SIZE);
> + memcpy(buf, virtio_desc_addr(dev, RX_Q, id - 1), RX_ELEM_SIZE);
>
> /* Move indices to next entries */
> last_rx_idx = last_rx_idx + 1;
> diff --git a/lib/libvirtio/virtio.c b/lib/libvirtio/virtio.c
> index fff0c7e54c19..d4db5f656888 100644
> --- a/lib/libvirtio/virtio.c
> +++ b/lib/libvirtio/virtio.c
> @@ -273,6 +273,17 @@ void virtio_fill_desc(struct vqs *vq, int id, uint64_t features,
> next %= vq->size;
>
> if (features & VIRTIO_F_VERSION_1) {
> + if (features & VIRTIO_F_IOMMU_PLATFORM) {
> + void *gpa = (void *) addr;
> +
> + if (!vq->desc_gpas) {
> + fprintf(stderr, "IOMMU setup has not been done!\n");
> + return;
> + }
> +
> + addr = SLOF_dma_map_in(gpa, len, 0);
> + vq->desc_gpas[id] = gpa;
> + }
> desc->addr = cpu_to_le64(addr);
> desc->len = cpu_to_le32(len);
> desc->flags = cpu_to_le16(flags);
> @@ -285,6 +296,32 @@ void virtio_fill_desc(struct vqs *vq, int id, uint64_t features,
> }
> }
>
> +void virtio_free_desc(struct vqs *vq, int id, uint64_t features)
> +{
> + struct vring_desc *desc;
> +
> + id %= vq->size;
> + desc = &vq->desc[id];
> +
> + if (features & VIRTIO_F_VERSION_1) {
> + if (features & VIRTIO_F_IOMMU_PLATFORM) {
> + SLOF_dma_map_out(le64_to_cpu(desc->addr),
> + 0, le32_to_cpu(desc->len));
> + vq->desc_gpas[id] = NULL;
> + }
> + }
> +}
On a 4.18 RHEL8 kernel I was unable to boot from virtio-blk, it complains the
disk isn't bootable and the H_PUT_TCE traces show:
qemu-system-ppc-19019 [045] .... 786844.067356: kvm_hcall_enter: VCPU 0: hcall=H_PUT_TCE GPR4-7=0x80000000,0x1000,0xe46b003,0xdc73350
qemu-system-ppc-19019 [045] .... 786844.067358: kvm_hcall_exit: VCPU 0: ret=RESUME_GUEST hcall_rc=H_SUCCESS
qemu-system-ppc-19019 [045] .... 786844.067361: kvm_hcall_enter: VCPU 0: hcall=H_PUT_TCE GPR4-7=0x80000000,0x2000,0xe46c003,0xdc73350
qemu-system-ppc-19019 [045] .... 786844.067362: kvm_hcall_exit: VCPU 0: ret=RESUME_GUEST hcall_rc=H_SUCCESS
qemu-system-ppc-19019 [041] .... 786844.070532: kvm_hcall_enter: VCPU 0: hcall=H_PUT_TCE GPR4-7=0x80000000,0x3000,0xe67b003,0xdc73490
qemu-system-ppc-19019 [041] .... 786844.070533: kvm_hcall_exit: VCPU 0: ret=RESUME_GUEST hcall_rc=H_SUCCESS
qemu-system-ppc-19019 [041] .... 786844.070817: kvm_hcall_enter: VCPU 0: hcall=H_PUT_TCE GPR4-7=0x80000000,0x4000,0xe469003,0xdc73490
qemu-system-ppc-19019 [041] .... 786844.070818: kvm_hcall_exit: VCPU 0: ret=RESUME_GUEST hcall_rc=H_SUCCESS
qemu-system-ppc-19019 [041] .... 786844.071102: kvm_hcall_enter: VCPU 0: hcall=H_PUT_TCE GPR4-7=0x80000000,0x5000,0xe67a003,0xdc73490
qemu-system-ppc-19019 [041] .... 786844.071103: kvm_hcall_exit: VCPU 0: ret=RESUME_GUEST hcall_rc=H_SUCCESS
qemu-system-ppc-19019 [041] .... 786844.071123: kvm_hcall_exit: VCPU 0: ret=RESUME_GUEST hcall_rc=H_SUCCESS
qemu-system-ppc-19019 [041] .... 786844.073532: kvm_hcall_enter: VCPU 0: hcall=H_PUT_TCE GPR4-7=0x80000000,0x3228,0x0,0xdc73488
qemu-system-ppc-19019 [041] .... 786844.073534: kvm_hcall_exit: VCPU 0: ret=RESUME_GUEST hcall_rc=H_PARAMETER
If I disable in-kernel TCE acceleration, or use TCG, it seems to work
fine. If I add the following hack it seems to fix things:
@@ -305,7 +307,8 @@ void virtio_free_desc(struct vqs *vq, int id, uint64_t features)
if (features & VIRTIO_F_VERSION_1) {
if (features & VIRTIO_F_IOMMU_PLATFORM) {
- SLOF_dma_map_out(le64_to_cpu(desc->addr),
+ fprintf(stderr, "mapping out desc->addr: %llx\n", le64_to_cpu(desc->addr));
+ SLOF_dma_map_out(le64_to_cpu(desc->addr) & ~(0xfff),
0, le32_to_cpu(desc->len));
vq->desc_gpas[id] = NULL;
}
I guess the kernel is a bit stricter about unmapping unaligned TCE entries? If
so, maybe we should align automatically in dma-map-out?
> +
> +void *virtio_desc_addr(struct virtio_device *vdev, int queue, int id)
> +{
> + struct vqs *vq = &vdev->vq[queue];
> +
> + if (vq->desc_gpas)
> + return vq->desc_gpas[id];
> +
> + return (void *) virtio_modern64_to_cpu(vdev, vq->desc[id].addr);
> +}
> +
> /**
> * Reset virtio device
> */
<snip>
> diff --git a/board-qemu/slof/OF.fs b/board-qemu/slof/OF.fs
> index a85f6c558e67..3e117ad03e09 100644
> --- a/board-qemu/slof/OF.fs
> +++ b/board-qemu/slof/OF.fs
> @@ -143,6 +143,9 @@ check-for-nvramrc
>
> 8a0 cp
>
> +\ For DMA functions used by client/package instances.
> +#include "dma-instance-function.fs"
> +
> \ The client interface.
> #include "client.fs"
> \ ELF binary file format.
> diff --git a/slof/fs/dma-instance-function.fs b/slof/fs/dma-instance-function.fs
> new file mode 100644
> index 000000000000..057181be0f44
> --- /dev/null
> +++ b/slof/fs/dma-instance-function.fs
> @@ -0,0 +1,28 @@
> +\ ****************************************************************************/
> +\ * Copyright (c) 2011 IBM Corporation
I copy/pasted the license header and forgot to update, should probably change
to 2019.
Also, if you think you need it:
Signed-off-by: Michael Roth <mdroth at linux.vnet.ibm.com>
> +\ * All rights reserved.
> +\ * This program and the accompanying materials
> +\ * are made available under the terms of the BSD License
> +\ * which accompanies this distribution, and is available at
> +\ * http://www.opensource.org/licenses/bsd-license.php
> +\ *
> +\ * Contributors:
> +\ * IBM Corporation - initial implementation
> +\ ****************************************************************************/
> +
> +\ DMA memory allocation functions
> +: dma-alloc ( size -- virt )
> + s" dma-alloc" $call-parent
> +;
> +
> +: dma-free ( virt size -- )
> + s" dma-free" $call-parent
> +;
> +
> +: dma-map-in ( virt size cacheable? -- devaddr )
> + s" dma-map-in" $call-parent
> +;
> +
> +: dma-map-out ( virt devaddr size -- )
> + s" dma-map-out" $call-parent
> +;
> --
> 2.17.1
>
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