linux-kernel - [PATCH 1/6] PCI: pci-bridge-emul: Make expansion ROM Base Address register read-only

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Message-Id: <20211124155944.1290-2-pali@kernel.org>
Date:   Wed, 24 Nov 2021 16:59:39 +0100
From:   Pali Rohár <pali@...nel.org>
To:     Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Marek Behún <kabel@...nel.org>
Cc:     linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/6] PCI: pci-bridge-emul: Make expansion ROM Base Address register read-only

If expansion ROM is unsupported (which is the case of pci-bridge-emul.c
driver) then ROM Base Address register must be implemented as read-only
register that return 0 when read, same as for unused Base Address
registers.

Signed-off-by: Pali Rohár <pali@...nel.org>
Fixes: 23a5fba4d941 ("PCI: Introduce PCI bridge emulated config space common logic")
Cc: stable@...r.kernel.org
---
 drivers/pci/pci-bridge-emul.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci-bridge-emul.c b/drivers/pci/pci-bridge-emul.c
index db97cddfc85e..5de8b8dde209 100644
--- a/drivers/pci/pci-bridge-emul.c
+++ b/drivers/pci/pci-bridge-emul.c
@@ -139,8 +139,13 @@ struct pci_bridge_reg_behavior pci_regs_behavior[PCI_STD_HEADER_SIZEOF / 4] = {
 		.ro = GENMASK(7, 0),
 	},
 
+	/*
+	 * If expansion ROM is unsupported then ROM Base Address register must
+	 * be implemented as read-only register that return 0 when read, same
+	 * as for unused Base Address registers.
+	 */
 	[PCI_ROM_ADDRESS1 / 4] = {
-		.rw = GENMASK(31, 11) | BIT(0),
+		.ro = ~0,
 	},
 
 	/*
-- 
2.20.1