[v2,2/3] misc: pci_endpoint_test: Handle 64-bit BARs properly

Message ID 20180208123346.20784-3-niklas.cassel@axis.com
State Changes Requested
Headers show
Series
  • PCI endpoint 64-bit BAR fixes
Related show

Commit Message

Niklas Cassel Feb. 8, 2018, 12:33 p.m.
A 64-bit BAR uses the succeeding BAR for the upper bits,
so we cannot simply call pci_ioremap_bar() on every single BAR.

Ignore BARs that does not have a valid resource length.

pci 0000:01:00.0: BAR 4: assigned [mem 0xc0300000-0xc031ffff 64bit]
pci 0000:01:00.0: BAR 2: assigned [mem 0xc0320000-0xc03203ff 64bit]
pci 0000:01:00.0: BAR 0: assigned [mem 0xc0320400-0xc03204ff 64bit]
pci-endpoint-test 0000:01:00.0: can't ioremap BAR 1: [??? 0x00000000 flags 0x0]
pci-endpoint-test 0000:01:00.0: failed to read BAR1
pci-endpoint-test 0000:01:00.0: can't ioremap BAR 3: [??? 0x00000000 flags 0x0]
pci-endpoint-test 0000:01:00.0: failed to read BAR3
pci-endpoint-test 0000:01:00.0: can't ioremap BAR 5: [??? 0x00000000 flags 0x0]
pci-endpoint-test 0000:01:00.0: failed to read BAR5

Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
---
Lorenzo/Bjorn: pci_resource_len() seems to fix my problem,
but is it the correct function to use here?
If BAR[x] is a 64-bit BAR, I'm assuming that pci_resource_len() on BAR[x+1]
will always return 0 (since BAR[x+1] cannot have any prefetchable/type bits
when BAR[x] is 64-bit).

 drivers/misc/pci_endpoint_test.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Lorenzo Pieralisi Feb. 26, 2018, 5:26 p.m. | #1
On Thu, Feb 08, 2018 at 01:33:45PM +0100, Niklas Cassel wrote:
> A 64-bit BAR uses the succeeding BAR for the upper bits,
> so we cannot simply call pci_ioremap_bar() on every single BAR.
> 
> Ignore BARs that does not have a valid resource length.
> 
> pci 0000:01:00.0: BAR 4: assigned [mem 0xc0300000-0xc031ffff 64bit]
> pci 0000:01:00.0: BAR 2: assigned [mem 0xc0320000-0xc03203ff 64bit]
> pci 0000:01:00.0: BAR 0: assigned [mem 0xc0320400-0xc03204ff 64bit]
> pci-endpoint-test 0000:01:00.0: can't ioremap BAR 1: [??? 0x00000000 flags 0x0]
> pci-endpoint-test 0000:01:00.0: failed to read BAR1
> pci-endpoint-test 0000:01:00.0: can't ioremap BAR 3: [??? 0x00000000 flags 0x0]
> pci-endpoint-test 0000:01:00.0: failed to read BAR3
> pci-endpoint-test 0000:01:00.0: can't ioremap BAR 5: [??? 0x00000000 flags 0x0]
> pci-endpoint-test 0000:01:00.0: failed to read BAR5
> 
> Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
> ---
> Lorenzo/Bjorn: pci_resource_len() seems to fix my problem,
> but is it the correct function to use here?
> If BAR[x] is a 64-bit BAR, I'm assuming that pci_resource_len() on BAR[x+1]
> will always return 0 (since BAR[x+1] cannot have any prefetchable/type bits
> when BAR[x] is 64-bit).
> 
>  drivers/misc/pci_endpoint_test.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
> index 320276f42653..3af31bfdcfdd 100644
> --- a/drivers/misc/pci_endpoint_test.c
> +++ b/drivers/misc/pci_endpoint_test.c
> @@ -534,6 +534,8 @@ static int pci_endpoint_test_probe(struct pci_dev *pdev,
>  	}
>  
>  	for (bar = BAR_0; bar <= BAR_5; bar++) {
> +		if (pci_resource_len(pdev, bar) == 0)
> +			continue;

Should not it be handled by checking the resource flags as you loop
through the bar counter and incrementing the bar counter (+1) if
IORESOURCE_MEM_64 is detected ?

I would like to get Bjorn's point of view on this since it is definitely
more comprehensive than mine.

Thanks,
Lorenzo

>  		base = pci_ioremap_bar(pdev, bar);
>  		if (!base) {
>  			dev_err(dev, "failed to read BAR%d\n", bar);
> -- 
> 2.14.2
>
Bjorn Helgaas Feb. 26, 2018, 6:09 p.m. | #2
On Mon, Feb 26, 2018 at 05:26:18PM +0000, Lorenzo Pieralisi wrote:
> On Thu, Feb 08, 2018 at 01:33:45PM +0100, Niklas Cassel wrote:
> > A 64-bit BAR uses the succeeding BAR for the upper bits,
> > so we cannot simply call pci_ioremap_bar() on every single BAR.
> > 
> > Ignore BARs that does not have a valid resource length.
> > 
> > pci 0000:01:00.0: BAR 4: assigned [mem 0xc0300000-0xc031ffff 64bit]
> > pci 0000:01:00.0: BAR 2: assigned [mem 0xc0320000-0xc03203ff 64bit]
> > pci 0000:01:00.0: BAR 0: assigned [mem 0xc0320400-0xc03204ff 64bit]
> > pci-endpoint-test 0000:01:00.0: can't ioremap BAR 1: [??? 0x00000000 flags 0x0]
> > pci-endpoint-test 0000:01:00.0: failed to read BAR1
> > pci-endpoint-test 0000:01:00.0: can't ioremap BAR 3: [??? 0x00000000 flags 0x0]
> > pci-endpoint-test 0000:01:00.0: failed to read BAR3
> > pci-endpoint-test 0000:01:00.0: can't ioremap BAR 5: [??? 0x00000000 flags 0x0]
> > pci-endpoint-test 0000:01:00.0: failed to read BAR5
> > 
> > Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
> > ---
> > Lorenzo/Bjorn: pci_resource_len() seems to fix my problem,
> > but is it the correct function to use here?
> > If BAR[x] is a 64-bit BAR, I'm assuming that pci_resource_len() on BAR[x+1]
> > will always return 0 (since BAR[x+1] cannot have any prefetchable/type bits
> > when BAR[x] is 64-bit).
> > 
> >  drivers/misc/pci_endpoint_test.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
> > index 320276f42653..3af31bfdcfdd 100644
> > --- a/drivers/misc/pci_endpoint_test.c
> > +++ b/drivers/misc/pci_endpoint_test.c
> > @@ -534,6 +534,8 @@ static int pci_endpoint_test_probe(struct pci_dev *pdev,
> >  	}
> >  
> >  	for (bar = BAR_0; bar <= BAR_5; bar++) {
> > +		if (pci_resource_len(pdev, bar) == 0)
> > +			continue;
> 
> Should not it be handled by checking the resource flags as you loop
> through the bar counter and incrementing the bar counter (+1) if
> IORESOURCE_MEM_64 is detected ?

I agree, pci_resource_len() is the wrong thing here.  The length
(actually the entire resource[x]) *should* be zero if the slot
corresponds to the upper bits of a 64-bit BAR, but I think it would be
more natural to do this:

  if (pci_resource_flags(pdev, bar) & IORESOURCE_MEM)
    base = pci_ioremap_bar(pdev, bar);

You *could* check for IORESOURCE_MEM_64 and increment "bar" if you
find it, but I don't think that's really idiomatic, and it builds in a
little bit of unnecessary knowledge about how the PCI core maps BAR
registers to the resource[] array.

> >  		base = pci_ioremap_bar(pdev, bar);
> >  		if (!base) {
> >  			dev_err(dev, "failed to read BAR%d\n", bar);
> > -- 
> > 2.14.2
> >

Patch

diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
index 320276f42653..3af31bfdcfdd 100644
--- a/drivers/misc/pci_endpoint_test.c
+++ b/drivers/misc/pci_endpoint_test.c
@@ -534,6 +534,8 @@  static int pci_endpoint_test_probe(struct pci_dev *pdev,
 	}
 
 	for (bar = BAR_0; bar <= BAR_5; bar++) {
+		if (pci_resource_len(pdev, bar) == 0)
+			continue;
 		base = pci_ioremap_bar(pdev, bar);
 		if (!base) {
 			dev_err(dev, "failed to read BAR%d\n", bar);