Re: [RFC PATCH 3/4] PCI/TSM: Derive the coherent-range IPA from CXL

[Andy Shevchenko]

On Mon, Oct 05, 2026 at 09:02:51AM +0200, Ankit Agrawal wrote:
> The DevIf report range with range ID 0xffff describes the device's
> coherent (CXL) memory window and unlike every other reported range
> carries no BAR number. Recognize
> PCI_TSM_DEVIF_REPORT_MMIO_RANGE_ID_COHERENT and recover that window's
> address from the CXL side of the device instead of treating it as a
> BAR-relative offset.
> 
> pci_tsm_coherent_range() resolves the window from pdev->coh_resource[],
> snapshotted once with the committed CXL HDM decoders range. The
> range to IPA conversion is applied onto range_base/range_len using
> pdev->coh_resource[]. The ascending BAR order checks stay on the BAR
> path only. The coherent range is required to be the last report entry
> and is not part of the BAR sequence.
> 
> An HDM decoded window lives in the CXL Fixed Memory Window and is not
> part of a BAR. So by construction, no pci_dev resource contains it. So
> the function pci_tsm_coh_resource_contains() validates the range against
> pdev->coh_resource[] instead; the same known-good snapshot
> pci_tsm_coherent_range() already trusts.

> Assisted-by: Claude:sonnet-5

Assisted-by: LLM

...

> +static bool pci_tsm_coh_resource_contains(struct pci_dev *pdev,
> +					  const struct resource *res)
> +{
> +	int i;
> +
> +	for (i = 0; i < PCI_CXL_MAX_COHERENT_RANGES; i++) {

	for (int i = 0...)

> +		struct resource *coh_res = &pdev->coh_resource[i];

		pci_resource_n()

> +		if ((coh_res->flags & IORESOURCE_MEM) &&
> +		    resource_contains(coh_res, res))
> +			return true;
> +	}
> +
> +	return false;
> +}

...

> +			for (j = 0; j < PCI_NUM_RESOURCES; j++)
> +				if (resource_contains(pci_resource_n(pdev, j), res))
> +					break;

pci_dev_for_each_resource()

...

> +static int pci_tsm_coherent_range(struct pci_dev *pdev, u64 *out_base,
> +				  u64 *out_size)

Instead of the last two you can use struct range.

> +{
> +	for (int i = 0; i < PCI_CXL_MAX_COHERENT_RANGES; i++) {
> +		struct resource *res = &pdev->coh_resource[i];

		pci_resource_n()

> +		if (!(res->flags & IORESOURCE_MEM))
> +			continue;

		resource_type()

> +		*out_base = res->start;
> +		*out_size = resource_size(res);
> +		return 0;
> +	}
> +
> +	return -ENODEV;
> +}

...

> +			if (pci_tsm_coherent_range(pdev, &range_base,
> +						   &range_len)) {

I would leave it on a single line.

> +				pci_dbg(pdev, "No CXL region or committed HDM decoder for coherent reporting range\n");
> +				return NULL;
> +			}


...

> +		range_off = coherent ? tsm_offset :
> +					tsm_offset - reporting_bar_base;

Indentation is broken. I think it's better to read when it's a single line.

-- 
With Best Regards,
Andy Shevchenko