Re: [PATCH v2 5/7] drm/xe/migrate: support MEM_COPY instruction

[Matthew Brost <matthew.brost@intel.com>]

On Mon, Oct 20, 2025 at 01:54:37PM +0100, Matthew Auld wrote:
> Make this the default on xe2+ when doing a copy. This has a few
> advantages over the exiting copy instruction:
> 
> 1) It has a special PAGE_COPY mode that claims to be optimised for
>    page-in/page-out, which is the vast majority of current users.
> 
> 2) It also has a simple BYTE_COPY mode that supports byte granularity
>    copying without any restrictions.
> 
> With 2) we can now easily skip the bounce buffer flow when copying
> buffers with strange sizing/alignment, like for memory_access. But that
> is left for the next patch.
> 
> v2 (Matt Brost):
>   - Use device info to check whether device should use the MEM_COPY
>     path. This should fit better with making this a configfs tunable.
>   - And with that also keep old path still functional on xe2 for possible
>     experimentation.
>   - Add a define for PAGE_COPY page-size.
> 
> BSpec: 57561
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>

Reviewed-by: Matthew Brost <matthew.brost@intel.com>

> ---
>  .../gpu/drm/xe/instructions/xe_gpu_commands.h |  6 ++
>  drivers/gpu/drm/xe/xe_device_types.h          |  2 +
>  drivers/gpu/drm/xe/xe_migrate.c               | 56 ++++++++++++++++++-
>  drivers/gpu/drm/xe/xe_pci.c                   |  4 ++
>  drivers/gpu/drm/xe/xe_pci_types.h             |  1 +
>  5 files changed, 66 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/instructions/xe_gpu_commands.h b/drivers/gpu/drm/xe/instructions/xe_gpu_commands.h
> index 8cfcd3360896..5d41ca297447 100644
> --- a/drivers/gpu/drm/xe/instructions/xe_gpu_commands.h
> +++ b/drivers/gpu/drm/xe/instructions/xe_gpu_commands.h
> @@ -31,6 +31,12 @@
>  #define   XY_FAST_COPY_BLT_D1_DST_TILE4	REG_BIT(30)
>  #define   XE2_XY_FAST_COPY_BLT_MOCS_INDEX_MASK	GENMASK(23, 20)
>  
> +#define MEM_COPY_CMD (2 << 29 | 0x5a << 22 | 0x8)
> +#define   MEM_COPY_PAGE_COPY_MODE REG_BIT(19)
> +#define   MEM_COPY_MATRIX_COPY REG_BIT(17)
> +#define   MEM_COPY_SRC_MOCS_INDEX_MASK	GENMASK(31, 28)
> +#define   MEM_COPY_DST_MOCS_INDEX_MASK	GENMASK(6, 3)
> +
>  #define	PVC_MEM_SET_CMD		(2 << 29 | 0x5b << 22)
>  #define   PVC_MEM_SET_CMD_LEN_DW	7
>  #define   PVC_MEM_SET_MATRIX		REG_BIT(17)
> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
> index 02c04ad7296e..6a62b520f5b5 100644
> --- a/drivers/gpu/drm/xe/xe_device_types.h
> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> @@ -305,6 +305,8 @@ struct xe_device {
>  		 * pcode mailbox commands.
>  		 */
>  		u8 has_mbx_power_limits:1;
> +		/** @info.has_mem_copy_instr: Device supports MEM_COPY instruction */
> +		u8 has_mem_copy_instr:1;
>  		/** @info.has_pxp: Device has PXP support */
>  		u8 has_pxp:1;
>  		/** @info.has_range_tlb_inval: Has range based TLB invalidations */
> diff --git a/drivers/gpu/drm/xe/xe_migrate.c b/drivers/gpu/drm/xe/xe_migrate.c
> index c966b6bad930..14ade32b8b69 100644
> --- a/drivers/gpu/drm/xe/xe_migrate.c
> +++ b/drivers/gpu/drm/xe/xe_migrate.c
> @@ -699,9 +699,9 @@ static void emit_copy_ccs(struct xe_gt *gt, struct xe_bb *bb,
>  }
>  
>  #define EMIT_COPY_DW 10
> -static void emit_copy(struct xe_gt *gt, struct xe_bb *bb,
> -		      u64 src_ofs, u64 dst_ofs, unsigned int size,
> -		      unsigned int pitch)
> +static void emit_xy_fast_copy(struct xe_gt *gt, struct xe_bb *bb, u64 src_ofs,
> +			      u64 dst_ofs, unsigned int size,
> +			      unsigned int pitch)
>  {
>  	struct xe_device *xe = gt_to_xe(gt);
>  	u32 mocs = 0;
> @@ -730,6 +730,56 @@ static void emit_copy(struct xe_gt *gt, struct xe_bb *bb,
>  	bb->cs[bb->len++] = upper_32_bits(src_ofs);
>  }
>  
> +#define PAGE_COPY_MODE_PS SZ_256 /* hw uses 256 bytes as the page-size */
> +static void emit_mem_copy(struct xe_gt *gt, struct xe_bb *bb, u64 src_ofs,
> +			  u64 dst_ofs, unsigned int size, unsigned int pitch)
> +{
> +	u32 mode, copy_type, width;
> +
> +	xe_gt_assert(gt, IS_ALIGNED(size, pitch));
> +	xe_gt_assert(gt, pitch <= U16_MAX);
> +	xe_gt_assert(gt, size);
> +
> +	if (IS_ALIGNED(size, PAGE_COPY_MODE_PS) &&
> +	    IS_ALIGNED(lower_32_bits(src_ofs), PAGE_COPY_MODE_PS) &&
> +	    IS_ALIGNED(lower_32_bits(dst_ofs), PAGE_COPY_MODE_PS)) {
> +		mode = MEM_COPY_PAGE_COPY_MODE;
> +		copy_type = 0; /* linear copy */
> +		width = size / PAGE_COPY_MODE_PS;
> +	} else {
> +		xe_gt_assert(gt, size / pitch <= U16_MAX);
> +		mode = 0; /* BYTE_COPY */
> +		copy_type = MEM_COPY_MATRIX_COPY;
> +		width = pitch;
> +	}
> +
> +	xe_gt_assert(gt, width <= U16_MAX);
> +
> +	bb->cs[bb->len++] = MEM_COPY_CMD | mode | copy_type;
> +	bb->cs[bb->len++] = width - 1;
> +	bb->cs[bb->len++] = size / pitch - 1; /* ignored by hw for page copy above */
> +	bb->cs[bb->len++] = pitch - 1;
> +	bb->cs[bb->len++] = pitch - 1;
> +	bb->cs[bb->len++] = lower_32_bits(src_ofs);
> +	bb->cs[bb->len++] = upper_32_bits(src_ofs);
> +	bb->cs[bb->len++] = lower_32_bits(dst_ofs);
> +	bb->cs[bb->len++] = upper_32_bits(dst_ofs);
> +	bb->cs[bb->len++] = FIELD_PREP(MEM_COPY_SRC_MOCS_INDEX_MASK, gt->mocs.uc_index) |
> +			    FIELD_PREP(MEM_COPY_DST_MOCS_INDEX_MASK, gt->mocs.uc_index);
> +}
> +
> +static void emit_copy(struct xe_gt *gt, struct xe_bb *bb,
> +		      u64 src_ofs, u64 dst_ofs, unsigned int size,
> +		      unsigned int pitch)
> +{
> +	struct xe_device *xe = gt_to_xe(gt);
> +
> +	if (xe->info.has_mem_copy_instr)
> +		emit_mem_copy(gt, bb, src_ofs, dst_ofs, size, pitch);
> +	else
> +		emit_xy_fast_copy(gt, bb, src_ofs, dst_ofs, size, pitch);
> +}
> +
>  static u64 xe_migrate_batch_base(struct xe_migrate *m, bool usm)
>  {
>  	return usm ? m->usm_batch_base_ofs : m->batch_base_ofs;
> diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
> index c3136141a953..8458d4ae8ee7 100644
> --- a/drivers/gpu/drm/xe/xe_pci.c
> +++ b/drivers/gpu/drm/xe/xe_pci.c
> @@ -342,6 +342,7 @@ static const struct xe_device_desc lnl_desc = {
>  	.has_display = true,
>  	.has_flat_ccs = 1,
>  	.has_pxp = true,
> +	.has_mem_copy_instr = true,
>  	.max_gt_per_tile = 2,
>  	.needs_scratch = true,
>  	.va_bits = 48,
> @@ -362,6 +363,7 @@ static const struct xe_device_desc bmg_desc = {
>  	.has_heci_cscfi = 1,
>  	.has_late_bind = true,
>  	.has_sriov = true,
> +	.has_mem_copy_instr = true,
>  	.max_gt_per_tile = 2,
>  	.needs_scratch = true,
>  	.subplatforms = (const struct xe_subplatform_desc[]) {
> @@ -378,6 +380,7 @@ static const struct xe_device_desc ptl_desc = {
>  	.has_display = true,
>  	.has_flat_ccs = 1,
>  	.has_sriov = true,
> +	.has_mem_copy_instr = true,
>  	.max_gt_per_tile = 2,
>  	.needs_scratch = true,
>  	.needs_shared_vf_gt_wq = true,
> @@ -657,6 +660,7 @@ static int xe_info_init_early(struct xe_device *xe,
>  	xe->info.has_pxp = desc->has_pxp;
>  	xe->info.has_sriov = xe_configfs_primary_gt_allowed(to_pci_dev(xe->drm.dev)) &&
>  		desc->has_sriov;
> +	xe->info.has_mem_copy_instr = desc->has_mem_copy_instr;
>  	xe->info.skip_guc_pc = desc->skip_guc_pc;
>  	xe->info.skip_mtcfg = desc->skip_mtcfg;
>  	xe->info.skip_pcode = desc->skip_pcode;
> diff --git a/drivers/gpu/drm/xe/xe_pci_types.h b/drivers/gpu/drm/xe/xe_pci_types.h
> index a4451bdc79fb..9892c063a9c5 100644
> --- a/drivers/gpu/drm/xe/xe_pci_types.h
> +++ b/drivers/gpu/drm/xe/xe_pci_types.h
> @@ -46,6 +46,7 @@ struct xe_device_desc {
>  	u8 has_late_bind:1;
>  	u8 has_llc:1;
>  	u8 has_mbx_power_limits:1;
> +	u8 has_mem_copy_instr:1;
>  	u8 has_pxp:1;
>  	u8 has_sriov:1;
>  	u8 needs_scratch:1;
> -- 
> 2.51.0
>