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

From: Christoph Hellwig <hch@lst.de>
To: Zhi Wang <zhi.wang.linux@gmail.com>
Cc: hch@lst.de, jgg@nvidia.com, jani.nikula@linux.intel.com,
	intel-gfx@lists.freedesktop.org,
	intel-gvt-dev@lists.freedesktop.org,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	Zhi Wang <zhi.a.wang@intel.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	Vivi Rodrigo <rodrigo.vivi@intel.com>,
	Zhenyu Wang <zhenyuw@linux.intel.com>
Subject: Re: [PATCH v6 2/3] i915/gvt: Save the initial HW state snapshot in i915
Date: Wed, 9 Feb 2022 08:32:01 +0100	[thread overview]
Message-ID: <20220209073201.GB9050@lst.de> (raw)
In-Reply-To: <20220208111151.13115-2-zhi.a.wang@intel.com>

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?