From:   Naveen Naidu <naveennaidu479@gmail.com>
To:     bhelgaas@google.com
Cc:     Naveen Naidu <naveennaidu479@gmail.com>,
        linux-kernel-mentees@lists.linuxfoundation.org,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        skhan@linuxfoundation.org,
        Jonathan Derrick <jonathan.derrick@linux.dev>,
        Nirmal Patel <nirmal.patel@linux.intel.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Rob Herring <robh@kernel.org>,
        =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= <kw@linux.com>
Subject: [PATCH v4 17/25] PCI: vmd: Use PCI_POSSIBLE_ERROR() to check read from hardware
Date:   Thu, 18 Nov 2021 19:33:27 +0530
Message-Id: <ed01cad87a2e35f3865275b5fb34290817a1ebf8.1637243717.git.naveennaidu479@gmail.com>
In-Reply-To: <cover.1637243717.git.naveennaidu479@gmail.com>
References: <cover.1637243717.git.naveennaidu479@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error.  There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

Use PCI_POSSIBLE_ERROR() to check the response we get when we read
data from hardware.

This helps unify PCI error response checking and make error checks
consistent and easier to find.

Reviewed-by: Jonathan Derrick <jonathan.derrick@linux.dev>
Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com>
---
 drivers/pci/controller/vmd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index a45e8e59d3d4..515d05605204 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -541,7 +541,7 @@ static int vmd_get_phys_offsets(struct vmd_dev *vmd, bool native_hint,
 		int ret;
 
 		ret = pci_read_config_dword(dev, PCI_REG_VMLOCK, &vmlock);
-		if (ret || vmlock == ~0)
+		if (ret || PCI_POSSIBLE_ERROR(vmlock))
 			return -ENODEV;
 
 		if (MB2_SHADOW_EN(vmlock)) {
-- 
2.25.1