linux-kernel - Re: [PATCH v6 2/3] i915/gvt: Save the initial HW state snapshot in i915

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Date:   Wed, 9 Feb 2022 08:32:01 +0100
From:   Christoph Hellwig <hch@....de>
To:     Zhi Wang <zhi.wang.linux@...il.com>
Cc:     hch@....de, jgg@...dia.com, jani.nikula@...ux.intel.com,
        intel-gfx@...ts.freedesktop.org,
        intel-gvt-dev@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Zhi Wang <zhi.a.wang@...el.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Vivi Rodrigo <rodrigo.vivi@...el.com>,
        Zhenyu Wang <zhenyuw@...ux.intel.com>
Subject: Re: [PATCH v6 2/3] i915/gvt: Save the initial HW state snapshot in
 i915

On Tue, Feb 08, 2022 at 06:11:50AM -0500, Zhi Wang wrote:
> +	struct drm_i915_private *dev_priv = iter->i915;
> +	u32 *mmio, i;
> +
> +	for (i = offset; i < offset + size; i += 4) {
> +		mmio = iter->data + i;
> +		*mmio = intel_uncore_read_notrace(to_gt(dev_priv)->uncore,
> +						  _MMIO(i));

This reads much stranger than:

	u32 *mmio = iter->data;

	for (i = offset; i < offset + size; i += 4) {
		mmio[i] = intel_uncore_read_notrace(to_gt(dev_priv)->uncore,
						    _MMIO(i));
	}

> +static int handle_mmio(struct intel_gvt_mmio_table_iter *iter,
> +		       u32 offset, u32 device, u32 size)
> +{
> +	if (WARN_ON(!IS_ALIGNED(offset, 4)))
> +		return -EINVAL;

Shouldn't this be in the caller of the method?

> +	save_mmio(iter, offset, size);
> +	return 0;

Now that the block callback is gone save_mmio and handle_mmio
can be merged.

> +	mem = vzalloc(2 * SZ_1M);

Don't we want a driver-wide constant for this instead of a magic number?