Re: [PATCH] PCI: endpoint: pci-epf-test: Limit PCIe BAR size for fixed BARs

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On 9/4/25 4:40 AM, Damien Le Moal wrote:

Hello Damien,

@@ -1050,7 +1051,13 @@ static int pci_epf_test_alloc_space(struct pci_epf *epf)
  		if (bar == test_reg_bar)
  			continue;
- base = pci_epf_alloc_space(epf, bar_size[bar], bar,
+		test_bar_size = bar_size[bar];
+
+		bar_fixed_size = epc_features->bar[bar].fixed_size;
+		if (epc_features->bar[bar].type == BAR_FIXED && bar_fixed_size)
+			test_bar_size = min(bar_size[bar], bar_fixed_size);

I think this can be simplified to:

		if (epc_features->bar[bar].type == BAR_FIXED)
			test_bar_size = epc_features->bar[bar].fixed_size;
		else
			test_bar_size = bar_size[bar];

because if the bar type is BAR_FIXED, then the size of the bar can only be its
fixed size.
That is correct, however, please consider the following case:

- The BAR under test is BAR4 , therefore the size requested by this driver is bar_size[4] = 131072 Bytes - The BAR4 on a hypothetical hardware is a fixed size BAR , 262144 Bytes large

With your proposed change, the "test_bar_size" would end up being 262144 Bytes , instead of 131072 Bytes without your proposed change , which I think is not the desired behavior.

What do you think ?




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