[Intel-gfx] [PATCH v1 03/12] drm/i915: vgpu pv command buffer transport protocol
Zhang, Xiaolin
xiaolin.zhang at intel.com
Mon Sep 21 05:33:47 UTC 2020
On Thu, 2020-09-10 at 16:20 +0300, Jani Nikula wrote:
> On Sat, 05 Sep 2020, Xiaolin Zhang <xiaolin.zhang at intel.com> 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 at intel.com>
> > ---
> > 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.
Sure. will change all the similar code. thanks.
>
> > + }
> > +
> > + *status = desc->status;
>
> Please have a blank line before the return. Recommended throughout
> the
> series.
Sure, will do it in whole series. thanks.
>
> > + 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.
Sure. NP.
>
> > +}
> > +
> > /*
> > * 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.
Sure. will fix the name prefix and use consistant name prefix.
>
> > 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);
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