On Wed, 17 Sep 2025, Lucas De Marchi wrote:
> Now that xe_pci.c calls the rebar directly, it doens't make sense to
> keep it in xe_vram.c since it's closer to the PCI initialization than to
> the vram. Move it to its own file.
>
> While at it, add a better comment to document the possible values for
> the vram_bar_size module parameter.
>
> Signed-off-by: Lucas De Marchi <lucas.demar...@intel.com>
> ---
> drivers/gpu/drm/xe/Makefile | 1 +
> drivers/gpu/drm/xe/xe_pci.c | 3 +-
> drivers/gpu/drm/xe/xe_pci_rebar.c | 125
> ++++++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/xe/xe_pci_rebar.h | 13 ++++
> drivers/gpu/drm/xe/xe_vram.c | 109 ---------------------------------
> drivers/gpu/drm/xe/xe_vram.h | 1 -
> 6 files changed, 141 insertions(+), 111 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> index 7a065c98a3b85..5a66d7a53d0db 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -95,6 +95,7 @@ xe-y += xe_bb.o \
> xe_observation.o \
> xe_pat.o \
> xe_pci.o \
> + xe_pci_rebar.o \
> xe_pcode.o \
> xe_pm.o \
> xe_preempt_fence.o \
> diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
> index 1f4120b535137..6cc5e7b6901a8 100644
> --- a/drivers/gpu/drm/xe/xe_pci.c
> +++ b/drivers/gpu/drm/xe/xe_pci.c
> @@ -27,6 +27,7 @@
> #include "xe_macros.h"
> #include "xe_mmio.h"
> #include "xe_module.h"
> +#include "xe_pci_rebar.h"
> #include "xe_pci_sriov.h"
> #include "xe_pci_types.h"
> #include "xe_pm.h"
> @@ -866,7 +867,7 @@ static int xe_pci_probe(struct pci_dev *pdev, const
> struct pci_device_id *ent)
> if (err)
> return err;
>
> - xe_vram_resize_bar(xe);
> + xe_pci_rebar(xe);
>
> err = xe_device_probe_early(xe);
> /*
> diff --git a/drivers/gpu/drm/xe/xe_pci_rebar.c
> b/drivers/gpu/drm/xe/xe_pci_rebar.c
> new file mode 100644
> index 0000000000000..e04416630b573
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_pci_rebar.c
> @@ -0,0 +1,125 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2025 Intel Corporation
> + */
> +
> +#include "xe_pci_rebar.h"
> +
> +#include <linux/pci.h>
> +#include <linux/types.h>
> +
> +#include <drm/drm_print.h>
> +
> +#include "regs/xe_bars.h"
> +#include "xe_device_types.h"
> +#include "xe_module.h"
> +
> +#define BAR_SIZE_SHIFT 20
> +
> +static void release_bars(struct pci_dev *pdev)
> +{
> + int resno;
> +
> + for (resno = PCI_STD_RESOURCES; resno < PCI_STD_RESOURCE_END; resno++) {
> + if (pci_resource_len(pdev, resno))
> + pci_release_resource(pdev, resno);
> + }
> +}
> +
> +static void resize_bar(struct xe_device *xe, int resno, resource_size_t size)
> +{
> + struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
> + int bar_size = pci_rebar_bytes_to_size(size);
> + int ret;
> +
> + release_bars(pdev);
> +
> + ret = pci_resize_resource(pdev, resno, bar_size);
> + if (ret) {
> + drm_info(&xe->drm, "Failed to resize BAR%d to %dM (%pe).
> Consider enabling 'Resizable BAR' support in your BIOS\n",
> + resno, 1 << bar_size, ERR_PTR(ret));
> + return;
> + }
> +
> + drm_info(&xe->drm, "BAR%d resized to %dM\n", resno, 1 << bar_size);
> +}
> +
> +void xe_pci_rebar(struct xe_device *xe)
> +{
> + int force_vram_bar_size = xe_modparam.force_vram_bar_size;
> + struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
> + struct pci_bus *root = pdev->bus;
> + resource_size_t current_size;
> + resource_size_t rebar_size;
> + struct resource *root_res;
> + u32 bar_size_mask;
> + u32 pci_cmd;
> + int i;
> +
> + /* gather some relevant info */
> + current_size = pci_resource_len(pdev, LMEM_BAR);
> + bar_size_mask = pci_rebar_get_possible_sizes(pdev, LMEM_BAR);
> +
> + if (!bar_size_mask)
> + return;
> +
> + /*
> + * Handle force_vram_bar_size:
> + * - negative: resize is disabled
> + * - 0: try to resize to maximum possible
> + * - positive: resize to specific value
> + */
> + if (force_vram_bar_size < 0)
> + return;
> +
> + if (force_vram_bar_size) {
> + u32 bar_size_bit;
> +
> + rebar_size = force_vram_bar_size * (resource_size_t)SZ_1M;
> +
> + bar_size_bit = bar_size_mask &
> BIT(pci_rebar_bytes_to_size(rebar_size));
> +
> + if (!bar_size_bit) {
> + drm_info(&xe->drm,
> + "Requested size: %lluMiB is not supported by
> rebar sizes: 0x%x. Leaving default: %lluMiB\n",
> + (u64)rebar_size >> 20, bar_size_mask,
> (u64)current_size >> 20);
> + return;
> + }
> +
> + rebar_size = 1ULL << (__fls(bar_size_bit) + BAR_SIZE_SHIFT);
> +
> + if (rebar_size == current_size)
> + return;
> + } else {
> + rebar_size = 1ULL << (__fls(bar_size_mask) + BAR_SIZE_SHIFT);
> +
> + /* only resize if larger than current */
> + if (rebar_size <= current_size)
> + return;
> + }
> +
> + drm_info(&xe->drm, "Attempting to resize bar from %lluMiB -> %lluMiB\n",
> + (u64)current_size >> 20, (u64)rebar_size >> 20);
BTW, if you want to do additional cleanups, all these 20 could be replaced
with ilog(SZ_1M) as it makes more obvious where that number comes from.
But this conflicts anyway with my rebar rework series so perhaps this
is not the best time for such cleanup.
--
i.
