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Message-ID: <687d4d54-09d6-4e30-921b-66c0e9bd0d51@intel.com>
Date: Thu, 23 Oct 2025 19:37:48 +0200
From: Michal Wajdeczko <michal.wajdeczko@...el.com>
To: Michał Winiarski <michal.winiarski@...el.com>, "Alex
Williamson" <alex.williamson@...hat.com>, Lucas De Marchi
<lucas.demarchi@...el.com>, Thomas Hellström
<thomas.hellstrom@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>,
Jason Gunthorpe <jgg@...pe.ca>, Yishai Hadas <yishaih@...dia.com>, Kevin Tian
<kevin.tian@...el.com>, <intel-xe@...ts.freedesktop.org>,
<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>, Matthew Brost
<matthew.brost@...el.com>
CC: <dri-devel@...ts.freedesktop.org>, Jani Nikula
<jani.nikula@...ux.intel.com>, Joonas Lahtinen
<joonas.lahtinen@...ux.intel.com>, Tvrtko Ursulin <tursulin@...ulin.net>,
David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, "Lukasz
Laguna" <lukasz.laguna@...el.com>
Subject: Re: [PATCH v2 11/26] drm/xe/pf: Increase PF GuC Buffer Cache size and
use it for VF migration
On 10/22/2025 12:41 AM, Michał Winiarski wrote:
> Contiguous PF GGTT VMAs can be scarce after creating VFs.
> Increase the GuC buffer cache size to 4M for PF so that we can fit GuC
> migration data (which currently maxes out at just under 4M) and use the
but the code below still uses 8M
> cache instead of allocating fresh BOs.
>
> Signed-off-by: Michał Winiarski <michal.winiarski@...el.com>
> ---
> drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c | 46 ++++++-------------
> drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h | 3 ++
> drivers/gpu/drm/xe/xe_guc.c | 12 ++++-
> 3 files changed, 28 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> index 4e26feb9c267f..04fad3126865c 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> @@ -11,7 +11,7 @@
> #include "xe_gt_sriov_pf_helpers.h"
> #include "xe_gt_sriov_pf_migration.h"
> #include "xe_gt_sriov_printk.h"
> -#include "xe_guc.h"
> +#include "xe_guc_buf.h"
> #include "xe_guc_ct.h"
> #include "xe_sriov.h"
> #include "xe_sriov_migration_data.h"
> @@ -57,73 +57,55 @@ static int pf_send_guc_query_vf_state_size(struct xe_gt *gt, unsigned int vfid)
>
> /* Return: number of state dwords saved or a negative error code on failure */
> static int pf_send_guc_save_vf_state(struct xe_gt *gt, unsigned int vfid,
> - void *buff, size_t size)
> + void *dst, size_t size)
> {
> const int ndwords = size / sizeof(u32);
> - struct xe_tile *tile = gt_to_tile(gt);
> - struct xe_device *xe = tile_to_xe(tile);
> struct xe_guc *guc = >->uc.guc;
> - struct xe_bo *bo;
> + CLASS(xe_guc_buf, buf)(&guc->buf, ndwords);
> int ret;
>
> xe_gt_assert(gt, size % sizeof(u32) == 0);
> xe_gt_assert(gt, size == ndwords * sizeof(u32));
>
> - bo = xe_bo_create_pin_map_novm(xe, tile,
> - ALIGN(size, PAGE_SIZE),
> - ttm_bo_type_kernel,
> - XE_BO_FLAG_SYSTEM |
> - XE_BO_FLAG_GGTT |
> - XE_BO_FLAG_GGTT_INVALIDATE, false);
> - if (IS_ERR(bo))
> - return PTR_ERR(bo);
> + if (!xe_guc_buf_is_valid(buf))
> + return -ENOBUFS;
> +
> + memset(xe_guc_buf_cpu_ptr(buf), 0, size);
hmm, I didn't find in the GuC spec that this buffer must be zeroed, so why bother?
>
> ret = guc_action_vf_save_restore(guc, vfid, GUC_PF_OPCODE_VF_SAVE,
> - xe_bo_ggtt_addr(bo), ndwords);
> + xe_guc_buf_flush(buf), ndwords);
> if (!ret)
> ret = -ENODATA;
> else if (ret > ndwords)
> ret = -EPROTO;
> else if (ret > 0)
> - xe_map_memcpy_from(xe, buff, &bo->vmap, 0, ret * sizeof(u32));
> + memcpy(dst, xe_guc_buf_sync_read(buf), ret * sizeof(u32));
nit: given this usage, maybe one day we should add optimized variant that copies directly to dst?
xe_guc_buf_sync_into(buf, dst, size);
>
> - xe_bo_unpin_map_no_vm(bo);
> return ret;
> }
>
> /* Return: number of state dwords restored or a negative error code on failure */
> static int pf_send_guc_restore_vf_state(struct xe_gt *gt, unsigned int vfid,
> - const void *buff, size_t size)
> + const void *src, size_t size)
> {
> const int ndwords = size / sizeof(u32);
> - struct xe_tile *tile = gt_to_tile(gt);
> - struct xe_device *xe = tile_to_xe(tile);
> struct xe_guc *guc = >->uc.guc;
> - struct xe_bo *bo;
> + CLASS(xe_guc_buf_from_data, buf)(&guc->buf, src, size);
> int ret;
>
> xe_gt_assert(gt, size % sizeof(u32) == 0);
> xe_gt_assert(gt, size == ndwords * sizeof(u32));
>
> - bo = xe_bo_create_pin_map_novm(xe, tile,
> - ALIGN(size, PAGE_SIZE),
> - ttm_bo_type_kernel,
> - XE_BO_FLAG_SYSTEM |
> - XE_BO_FLAG_GGTT |
> - XE_BO_FLAG_GGTT_INVALIDATE, false);
> - if (IS_ERR(bo))
> - return PTR_ERR(bo);
> -
> - xe_map_memcpy_to(xe, &bo->vmap, 0, buff, size);
> + if (!xe_guc_buf_is_valid(buf))
> + return -ENOBUFS;
>
> ret = guc_action_vf_save_restore(guc, vfid, GUC_PF_OPCODE_VF_RESTORE,
> - xe_bo_ggtt_addr(bo), ndwords);
> + xe_guc_buf_flush(buf), ndwords);
> if (!ret)
> ret = -ENODATA;
> else if (ret > ndwords)
> ret = -EPROTO;
>
> - xe_bo_unpin_map_no_vm(bo);
> return ret;
> }
>
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h
> index e2d41750f863c..4f2f2783339c3 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h
> @@ -11,6 +11,9 @@
> struct xe_gt;
> struct xe_sriov_migration_data;
>
> +/* TODO: get this information by querying GuC in the future */
> +#define XE_GT_SRIOV_PF_MIGRATION_GUC_DATA_MAX_SIZE SZ_8M
so it's 8M or 4M ?
maybe wrap that into function now
u32 xe_gt_sriov_pf_migration_guc_data_size(struct xe_gt *gt)
{
if (xe_sriov_pf_migration_supported(gt_to_xe))
return SZ_4M; /* TODO: ... */
return 0;
}
> +
> int xe_gt_sriov_pf_migration_init(struct xe_gt *gt);
> int xe_gt_sriov_pf_migration_save_guc_state(struct xe_gt *gt, unsigned int vfid);
> int xe_gt_sriov_pf_migration_restore_guc_state(struct xe_gt *gt, unsigned int vfid);
> diff --git a/drivers/gpu/drm/xe/xe_guc.c b/drivers/gpu/drm/xe/xe_guc.c
> index 7c65528859ecb..cd6ab277a7876 100644
> --- a/drivers/gpu/drm/xe/xe_guc.c
> +++ b/drivers/gpu/drm/xe/xe_guc.c
> @@ -24,6 +24,7 @@
> #include "xe_gt_printk.h"
> #include "xe_gt_sriov_vf.h"
> #include "xe_gt_throttle.h"
> +#include "xe_gt_sriov_pf_migration.h"
> #include "xe_guc_ads.h"
> #include "xe_guc_buf.h"
> #include "xe_guc_capture.h"
> @@ -40,6 +41,7 @@
> #include "xe_mmio.h"
> #include "xe_platform_types.h"
> #include "xe_sriov.h"
> +#include "xe_sriov_pf_migration.h"
> #include "xe_uc.h"
> #include "xe_uc_fw.h"
> #include "xe_wa.h"
> @@ -821,6 +823,14 @@ static int vf_guc_init_post_hwconfig(struct xe_guc *guc)
> return 0;
> }
>
> +static u32 guc_buf_cache_size(struct xe_guc *guc)
> +{
> + if (IS_SRIOV_PF(guc_to_xe(guc)) && xe_sriov_pf_migration_supported(guc_to_xe(guc)))
> + return XE_GT_SRIOV_PF_MIGRATION_GUC_DATA_MAX_SIZE;
then
u32 size = XE_GUC_BUF_CACHE_DEFAULT_SIZE;
if (IS_SRIOV_PF(guc_to_xe(guc)))
size += xe_gt_sriov_pf_migration_guc_data_size(guc_to_gt(guc));
return size;
> + else
> + return XE_GUC_BUF_CACHE_DEFAULT_SIZE;
> +}
> +
> /**
> * xe_guc_init_post_hwconfig - initialize GuC post hwconfig load
> * @guc: The GuC object
> @@ -860,7 +870,7 @@ int xe_guc_init_post_hwconfig(struct xe_guc *guc)
> if (ret)
> return ret;
>
> - ret = xe_guc_buf_cache_init(&guc->buf, XE_GUC_BUF_CACHE_DEFAULT_SIZE);
> + ret = xe_guc_buf_cache_init(&guc->buf, guc_buf_cache_size(guc));
> if (ret)
> return ret;
>
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