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From: Russ Weight <russell.h.weight@intel.com>
To: mdf@kernel.org, linux-fpga@vger.kernel.org
Cc: trix@redhat.com, lgoncalv@redhat.com, yilun.xu@intel.com,
	hao.wu@intel.com, matthew.gerlach@intel.com, rc@silicom.dk,
	Russ Weight <russell.h.weight@intel.com>,
	stable@vger.kernel.org
Subject: [PATCH 1/1] fpga: dfl: Avoid reads to AFU CSRs during enumeration
Date: Thu, 16 Sep 2021 14:07:33 -0700	[thread overview]
Message-ID: <20210916210733.153388-1-russell.h.weight@intel.com> (raw)

CSR address space for Accelerator Functional Units (AFU) is not available
during the early Device Feature List (DFL) enumeration. Early access
to this space results in invalid data and port errors. This change adds
a condition to prevent an early read from the AFU CSR space.

Signed-off-by: Russ Weight <russell.h.weight@intel.com>

Fixes: 23bcda750558 ("fpga: dfl: expose feature revision from struct
dfl_device")
Cc: stable@vger.kernel.org
---
 drivers/fpga/dfl.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
index c99b78ee008a..f86666cf2c6a 100644
--- a/drivers/fpga/dfl.c
+++ b/drivers/fpga/dfl.c
@@ -1019,16 +1019,18 @@ create_feature_instance(struct build_feature_devs_info *binfo,
 {
 	unsigned int irq_base, nr_irqs;
 	struct dfl_feature_info *finfo;
+	u8 revision = 0;
 	int ret;
-	u8 revision;
 	u64 v;
 
-	v = readq(binfo->ioaddr + ofst);
-	revision = FIELD_GET(DFH_REVISION, v);
+	if (fid != FEATURE_ID_AFU) {
+		v = readq(binfo->ioaddr + ofst);
+		revision = FIELD_GET(DFH_REVISION, v);
 
-	/* read feature size and id if inputs are invalid */
-	size = size ? size : feature_size(v);
-	fid = fid ? fid : feature_id(v);
+		/* read feature size and id if inputs are invalid */
+		size = size ? size : feature_size(v);
+		fid = fid ? fid : feature_id(v);
+	}
 
 	if (binfo->len - ofst < size)
 		return -EINVAL;
-- 
2.25.1


             reply	other threads:[~2021-09-16 21:08 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-16 21:07 Russ Weight [this message]
2021-09-16 22:24 ` [PATCH 1/1] fpga: dfl: Avoid reads to AFU CSRs during enumeration Moritz Fischer
2021-09-16 22:34   ` Russ Weight
2021-09-16 22:50     ` Moritz Fischer
2021-09-17 18:24       ` Russ Weight
2021-09-17  5:42 ` Greg KH
2021-09-17 16:26   ` Moritz Fischer

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