linux-kernel - [PATCH v5 4/6] PCI/IOV: Check that VF BAR fits within the reservation

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Message-ID: <20250312225949.969716-5-michal.winiarski@intel.com>
Date: Wed, 12 Mar 2025 23:59:47 +0100
From: Michał Winiarski <michal.winiarski@...el.com>
To: <linux-pci@...r.kernel.org>, <intel-xe@...ts.freedesktop.org>,
	<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>, "Bjorn
 Helgaas" <bhelgaas@...gle.com>, Christian König
	<christian.koenig@....com>, Krzysztof Wilczyński
	<kw@...ux.com>, Ilpo Järvinen
	<ilpo.jarvinen@...ux.intel.com>
CC: Rodrigo Vivi <rodrigo.vivi@...el.com>, Michal Wajdeczko
	<michal.wajdeczko@...el.com>, Lucas De Marchi <lucas.demarchi@...el.com>,
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
	<mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
	<airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Matt Roper
	<matthew.d.roper@...el.com>, Michał Winiarski
	<michal.winiarski@...el.com>
Subject: [PATCH v5 4/6] PCI/IOV: Check that VF BAR fits within the reservation

When the resource representing VF MMIO BAR reservation is created, its
size is always large enough to accommodate the BAR of all SR-IOV Virtual
Functions that can potentially be created (total VFs).

If it's not possible to accommodate all VFs - the resource is not
assigned and no VFs can be created.

The following patch will allow VF BAR size to be modified by drivers at
a later point in time, which means that the check for resource
assignment is no longer sufficient.

Add an additional check that verifies that VF BAR for all enabled VFs
fits within the underlying reservation resource.

Signed-off-by: Michał Winiarski <michal.winiarski@...el.com>
---
 drivers/pci/iov.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 7cc17e898cea7..d6d63083884e6 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -646,8 +646,13 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
 
 	nres = 0;
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
+		resource_size_t vf_bar_sz =
+			pci_iov_resource_size(dev,
+					      pci_resource_num_from_vf_bar(i));
 		bars |= (1 << pci_resource_num_from_vf_bar(i));
 		res = &dev->resource[pci_resource_num_from_vf_bar(i)];
+		if (vf_bar_sz * nr_virtfn > resource_size(res))
+			continue;
 		if (res->parent)
 			nres++;
 	}
-- 
2.48.1