On Sat, 05 Sep 2020, Xiaolin Zhang <xiaolin.zhang@xxxxxxxxx> wrote:
> based on the common shared memory, vgpu pv command transport buffer (CTB)
> protocol is implemented which is a simple pv command buffer ring with pv
> command descriptor used to perform guest-2-gvt single direction commucation
> between guest and host GVTg.
>
> with this CTB, guest can send PV command with PV data to host to perform PV
> commands in host side.
>
> Signed-off-by: Xiaolin Zhang <xiaolin.zhang@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_pvinfo.h | 1 +
> drivers/gpu/drm/i915/i915_vgpu.c | 195 ++++++++++++++++++++++++++++++++++++-
> drivers/gpu/drm/i915/i915_vgpu.h | 53 ++++++++++
> 3 files changed, 247 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_pvinfo.h b/drivers/gpu/drm/i915/i915_pvinfo.h
> index 1d44876..ded93c5 100644
> --- a/drivers/gpu/drm/i915/i915_pvinfo.h
> +++ b/drivers/gpu/drm/i915/i915_pvinfo.h
> @@ -49,6 +49,7 @@ enum vgt_g2v_type {
> VGT_G2V_EXECLIST_CONTEXT_CREATE,
> VGT_G2V_EXECLIST_CONTEXT_DESTROY,
> VGT_G2V_SHARED_PAGE_REGISTER,
> + VGT_G2V_PV_SEND_TRIGGER,
> VGT_G2V_MAX,
> };
>
> diff --git a/drivers/gpu/drm/i915/i915_vgpu.c b/drivers/gpu/drm/i915/i915_vgpu.c
> index 8b2b451..e856eff 100644
> --- a/drivers/gpu/drm/i915/i915_vgpu.c
> +++ b/drivers/gpu/drm/i915/i915_vgpu.c
> @@ -370,6 +370,183 @@ int intel_vgt_balloon(struct i915_ggtt *ggtt)
> * i915 vgpu PV support for Linux
> */
>
> +/**
> + * wait_for_desc_update - Wait for the command buffer descriptor update.
> + * @desc: buffer descriptor
> + * @fence: response fence
> + * @status: placeholder for status
> + *
> + * GVTg will update command buffer descriptor with new fence and status
> + * after processing the command identified by the fence. Wait for
> + * specified fence and then read from the descriptor status of the
> + * command.
> + *
> + * Return:
> + * * 0 response received (status is valid)
> + * * -ETIMEDOUT no response within hardcoded timeout
> + */
> +static int wait_for_desc_update(struct vgpu_pv_ct_buffer_desc *desc,
> + u32 fence, u32 *status)
> +{
> + int err;
> +
> +#define done (READ_ONCE(desc->fence) == fence)
> + err = wait_for_us(done, 5);
> + if (err)
> + err = wait_for(done, 10);
> +#undef done
> +
> + if (unlikely(err)) {
> + DRM_ERROR("CT: fence %u failed; reported fence=%u\n",
> + fence, desc->fence);
drm_err() please.
> + }
> +
> + *status = desc->status;
Please have a blank line before the return. Recommended throughout the
series.
> + return err;
> +}
> +
> +/**
> + * CTB Guest to GVT request
> + *
> + * Format of the CTB Guest to GVT request message is as follows::
> + *
> + * +------------+---------+---------+---------+---------+
> + * | msg[0] | [1] | [2] | ... | [n-1] |
> + * +------------+---------+---------+---------+---------+
> + * | MESSAGE | MESSAGE PAYLOAD |
> + * + HEADER +---------+---------+---------+---------+
> + * | | 0 | 1 | ... | n |
> + * +============+=========+=========+=========+=========+
> + * | len >= 1 | FENCE | request specific data |
> + * +------+-----+---------+---------+---------+---------+
> + *
> + * ^-----------------len-------------------^
> + */
> +static int pv_command_buffer_write(struct i915_virtual_gpu_pv *pv,
> + const u32 *action, u32 len /* in dwords */, u32 fence)
> +{
> + struct vgpu_pv_ct_buffer_desc *desc = pv->ctb.desc;
> + u32 head = desc->head / 4; /* in dwords */
> + u32 tail = desc->tail / 4; /* in dwords */
> + u32 size = desc->size / 4; /* in dwords */
> + u32 used; /* in dwords */
> + u32 header;
> + u32 *cmds = pv->ctb.cmds;
> + unsigned int i;
> +
> + GEM_BUG_ON(desc->size % 4);
> + GEM_BUG_ON(desc->head % 4);
> + GEM_BUG_ON(desc->tail % 4);
> + GEM_BUG_ON(tail >= size);
> +
> + /* tail == head condition indicates empty */
> + if (tail < head)
> + used = (size - head) + tail;
> + else
> + used = tail - head;
> +
> + /* make sure there is a space including extra dw for the fence */
> + if (unlikely(used + len + 1 >= size))
> + return -ENOSPC;
> +
> + /*
> + * Write the message. The format is the following:
> + * DW0: header (including action code)
> + * DW1: fence
> + * DW2+: action data
> + */
> + header = (len << PV_CT_MSG_LEN_SHIFT) |
> + (PV_CT_MSG_WRITE_FENCE_TO_DESC) |
> + (action[0] << PV_CT_MSG_ACTION_SHIFT);
> +
> + cmds[tail] = header;
> + tail = (tail + 1) % size;
> +
> + cmds[tail] = fence;
> + tail = (tail + 1) % size;
> +
> + for (i = 1; i < len; i++) {
> + cmds[tail] = action[i];
> + tail = (tail + 1) % size;
> + }
> +
> + /* now update desc tail (back in bytes) */
> + desc->tail = tail * 4;
> + GEM_BUG_ON(desc->tail > desc->size);
> +
> + return 0;
> +}
> +
> +static u32 pv_get_next_fence(struct i915_virtual_gpu_pv *pv)
> +{
> + /* For now it's trivial */
> + return ++pv->next_fence;
> +}
> +
> +static int pv_send(struct drm_i915_private *i915,
> + const u32 *action, u32 len, u32 *status)
> +{
> + struct i915_virtual_gpu *vgpu = &i915->vgpu;
> + struct i915_virtual_gpu_pv *pv = vgpu->pv;
> +
> + struct vgpu_pv_ct_buffer_desc *desc = pv->ctb.desc;
> +
> + u32 fence;
> + int err;
> +
> + GEM_BUG_ON(!len);
> + GEM_BUG_ON(len & ~PV_CT_MSG_LEN_MASK);
> +
> + fence = pv_get_next_fence(pv);
> + err = pv_command_buffer_write(pv, action, len, fence);
> + if (unlikely(err))
> + goto unlink;
> +
> + i915->vgpu.pv->notify(i915);
> +
> + err = wait_for_desc_update(desc, fence, status);
> + if (unlikely(err))
> + goto unlink;
> +
> + if ((*status)) {
> + err = -EIO;
> + goto unlink;
> + }
> +
> + err = (*status);
> +unlink:
> + return err;
> +}
> +
> +static int intel_vgpu_pv_send_command_buffer(struct drm_i915_private *i915,
> + u32 *action, u32 len)
> +{
> + struct i915_virtual_gpu *vgpu = &i915->vgpu;
> + unsigned long flags;
> +
> + u32 status = ~0; /* undefined */
> + int ret;
> +
> + spin_lock_irqsave(&vgpu->pv->lock, flags);
> +
> + ret = pv_send(i915, action, len, &status);
> + if (unlikely(ret < 0)) {
> + DRM_ERROR("PV: send action %#X failed; err=%d status=%#X\n",
> + action[0], ret, status);
> + } else if (unlikely(ret)) {
> + DRM_ERROR("PV: send action %#x returned %d (%#x)\n",
> + action[0], ret, ret);
drm_err() please.
> + }
> +
> + spin_unlock_irqrestore(&vgpu->pv->lock, flags);
> + return ret;
> +}
> +
> +static void intel_vgpu_pv_notify_mmio(struct drm_i915_private *dev_priv)
> +{
> + I915_WRITE(vgtif_reg(g2v_notify), VGT_G2V_PV_SEND_TRIGGER);
Please do not add any more I915_WRITE() uses. intel_uncore_write() please.
> +}
> +
> /*
> * shared_page setup for VGPU PV features
> */
> @@ -385,7 +562,7 @@ static int intel_vgpu_setup_shared_page(struct drm_i915_private *i915,
>
> /* We allocate 1 page shared between guest and GVT for data exchange.
> * _______________________________
> - * |version |
> + * |version|PV_DESCs(SEND) |
> * |_______________________________PAGE/8
> * | |
> * |_______________________________PAGE/4
> @@ -393,7 +570,7 @@ static int intel_vgpu_setup_shared_page(struct drm_i915_private *i915,
> * | |
> * | |
> * |_______________________________PAGE/2
> - * | |
> + * |PV_CMDs(SEND) |
> * | |
> * | |
> * | |
> @@ -403,6 +580,8 @@ static int intel_vgpu_setup_shared_page(struct drm_i915_private *i915,
> * |_______________________________|
> *
> * 0 offset: PV version area
> + * PAGE/4 offset: PV command buffer command descriptor area
> + * PAGE/2 offset: PV command buffer command data area
> */
>
> base = (struct gvt_shared_page *)get_zeroed_page(GFP_KERNEL);
> @@ -441,6 +620,18 @@ static int intel_vgpu_setup_shared_page(struct drm_i915_private *i915,
> DRM_INFO("vgpu PV ver major %d and minor %d\n", ver_maj, ver_min);
> i915->vgpu.pv = pv;
> pv->shared_page = base;
> +
> + /* setup PV command buffer ptr */
> + pv->ctb.cmds = (void *)base + PV_CMD_OFF;
> + pv->ctb.desc = (void *)base + PV_DESC_OFF;
> + pv->ctb.desc->size = PAGE_SIZE/2;
> + pv->ctb.desc->addr = PV_CMD_OFF;
> +
> + /* setup PV command buffer callback */
> + pv->send = intel_vgpu_pv_send_command_buffer;
> + pv->notify = intel_vgpu_pv_notify_mmio;
> + spin_lock_init(&pv->lock);
> +
> return ret;
> err:
> __free_page(virt_to_page(base));
> diff --git a/drivers/gpu/drm/i915/i915_vgpu.h b/drivers/gpu/drm/i915/i915_vgpu.h
> index aeef20f..f2826f9 100644
> --- a/drivers/gpu/drm/i915/i915_vgpu.h
> +++ b/drivers/gpu/drm/i915/i915_vgpu.h
> @@ -31,6 +31,8 @@ struct i915_ggtt;
>
> #define PV_MAJOR 0
> #define PV_MINOR 1
> +#define PV_DESC_OFF (PAGE_SIZE/256)
> +#define PV_CMD_OFF (PAGE_SIZE/2)
>
> /* define different PV capabilities */
> enum pv_caps {
> @@ -43,8 +45,59 @@ struct gvt_shared_page {
> u16 ver_minor;
> };
>
> +/*
> + * Definition of the command transport message header (DW0)
> + *
> + * bit[0..4] message len (in dwords)
> + * bit[5..7] reserved
> + * bit[8..8] write fence to desc
> + * bit[9..15] reserved
> + * bit[16..31] action code
> + */
> +#define PV_CT_MSG_LEN_SHIFT 0
> +#define PV_CT_MSG_LEN_MASK 0x1F
> +#define PV_CT_MSG_WRITE_FENCE_TO_DESC (1 << 8)
> +#define PV_CT_MSG_ACTION_SHIFT 16
> +#define PV_CT_MSG_ACTION_MASK 0xFFFF
> +
> +/* PV command transport buffer descriptor */
> +struct vgpu_pv_ct_buffer_desc {
> + u32 addr; /* gpa address */
> + u32 size; /* size in bytes */
> + u32 head; /* offset updated by GVT */
> + u32 tail; /* offset updated by owner */
> +
> + u32 fence; /* fence updated by GVT */
> + u32 status; /* status updated by GVT */
> +} __packed;
> +
> +/** PV single command transport buffer.
> + *
> + * A single command transport buffer consists of two parts, the header
> + * record (command transport buffer descriptor) and the actual buffer which
> + * holds the commands.
> + *
> + * @desc: pointer to the buffer descriptor
> + * @cmds: pointer to the commands buffer
> + */
> +struct vgpu_pv_ct_buffer {
> + struct vgpu_pv_ct_buffer_desc *desc;
> + u32 *cmds;
> +};
> +
Again, another name prefix that is not in line with the rest of the file
or driver.
> struct i915_virtual_gpu_pv {
> struct gvt_shared_page *shared_page;
> +
> + /* PV command buffer support */
> + struct vgpu_pv_ct_buffer ctb;
> + u32 next_fence;
> +
> + /* To serialize the vgpu PV send actions */
> + spinlock_t lock;
> +
> + /* VGPU's PV specific send function */
> + int (*send)(struct drm_i915_private *dev_priv, u32 *data, u32 len);
> + void (*notify)(struct drm_i915_private *dev_priv);
> };
>
> void intel_vgpu_detect(struct drm_i915_private *i915);
--
Jani Nikula, Intel Open Source Graphics Center
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