Re: [PATCH v1 2/7] fpga: dfl: check feature type before parse irq info

On Tue, Feb 15, 2022 at 06:49:05AM -0800, Tom Rix wrote:

On 2/14/22 3:26 AM, Tianfei zhang wrote:

quoted

From: Tianfei Zhang <redacted>

The feature ID of "Port User Interrupt" and the
"PMCI Subsystem" are identical, 0x12, but one is for FME,
other is for Port. It should check the feature type While
parsing the irq info in parse_feature_irqs().

This seems like a bug fix and not part of iofs feature.

Split this out of the patchset.

This is a workaround a hardware problem, there should be some comments to
the effect that you can't trust _this_ or _that_ feature id and some special
handling earlier.

The ambiguity of feature id is a problem, and this sort of bug will happen

Actually this is not the feature id definition problem. The identity of the
feature is determined by the dfl_id_type(FME, PORT) AND feature_id. So the
driver should match the dfl_id_type & feature_id to know what feature it
is.

Thanks,
Yilun

again.

What can be done to prevent this in the future ?

quoted

Signed-off-by: Tianfei Zhang <redacted>
---
  drivers/fpga/dfl.c | 11 +++++++++++
  1 file changed, 11 insertions(+)

diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
index 599bb21d86af..26f8cf890700 100644
--- a/drivers/fpga/dfl.c
+++ b/drivers/fpga/dfl.c

@@ -940,9 +940,14 @@ static int parse_feature_irqs(struct build_feature_devs_info *binfo,
  {
  	void __iomem *base = binfo->ioaddr + ofst;
  	unsigned int i, ibase, inr = 0;
+	enum dfl_id_type type;
  	int virq;
  	u64 v;
+	type = feature_dev_id_type(binfo->feature_dev);
+	if (type >= DFL_ID_MAX)
+		return -EINVAL;
+
  	/*
  	 * Ideally DFL framework should only read info from DFL header, but
  	 * current version DFL only provides mmio resources information for

@@ -959,16 +964,22 @@ static int parse_feature_irqs(struct build_feature_devs_info *binfo,
  	 */
  	switch (fid) {
  	case PORT_FEATURE_ID_UINT:
+		if (type != PORT_ID)
+			break;

Instead of embedding a break in the switch, break the switch into fme switch
and port switch

if (type == PORT_ID)

  port-switch

else if (type == FME_ID

  fme-switch

Tom

quoted

  		v = readq(base + PORT_UINT_CAP);
  		ibase = FIELD_GET(PORT_UINT_CAP_FST_VECT, v);
  		inr = FIELD_GET(PORT_UINT_CAP_INT_NUM, v);
  		break;
  	case PORT_FEATURE_ID_ERROR:
+		if (type != PORT_ID)
+			break;
  		v = readq(base + PORT_ERROR_CAP);
  		ibase = FIELD_GET(PORT_ERROR_CAP_INT_VECT, v);
  		inr = FIELD_GET(PORT_ERROR_CAP_SUPP_INT, v);
  		break;
  	case FME_FEATURE_ID_GLOBAL_ERR:
+		if (type != FME_ID)
+			break;
  		v = readq(base + FME_ERROR_CAP);
  		ibase = FIELD_GET(FME_ERROR_CAP_INT_VECT, v);
  		inr = FIELD_GET(FME_ERROR_CAP_SUPP_INT, v);