On 2021/8/10 1:31, Bjorn Helgaas wrote:
On Sat, Aug 07, 2021 at 03:11:34PM +0800, Dongdong Liu wrote:
On 2021/8/6 2:12, Bjorn Helgaas wrote:
On Wed, Aug 04, 2021 at 09:47:08PM +0800, Dongdong Liu wrote:
Add a 10-Bit Tag check in the P2PDMA code to ensure that a device with
10-Bit Tag Requester doesn't interact with a device that does not
support 10-BIT Tag Completer. Before that happens, the kernel should
emit a warning. "echo 0 > /sys/bus/pci/devices/.../10bit_tag" to
disable 10-BIT Tag Requester for PF device.
"echo 0 > /sys/bus/pci/devices/.../sriov_vf_10bit_tag_ctl" to disable
10-BIT Tag Requester for VF device.
s/10-BIT/10-Bit/ several times.
Will fix.
Add blank lines between paragraphs.
Will fix.
Signed-off-by: Dongdong Liu <liudongdong3@xxxxxxxxxx>
---
drivers/pci/p2pdma.c | 40 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 50cdde3..948f2be 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -19,6 +19,7 @@
#include <linux/random.h>
#include <linux/seq_buf.h>
#include <linux/xarray.h>
+#include "pci.h"
enum pci_p2pdma_map_type {
PCI_P2PDMA_MAP_UNKNOWN = 0,
@@ -410,6 +411,41 @@ static unsigned long map_types_idx(struct pci_dev *client)
(client->bus->number << 8) | client->devfn;
}
+static bool check_10bit_tags_vaild(struct pci_dev *a, struct pci_dev *b,
s/vaild/valid/
Or maybe s/valid/safe/ or s/valid/supported/, since "valid" isn't
quite the right word here. We want to know whether the source is
enabled to generate 10-bit tags, and if so, whether the destination
can handle them.
"if (check_10bit_tags_valid())" does not make sense because
"check_10bit_tags_valid()" is not a question with a yes/no answer.
"10bit_tags_valid()" *might* be, because "if (10bit_tags_valid())"
makes sense. But I don't think you can start with a digit.
Or maybe you want to invert the sense, e.g.,
"10bit_tags_unsupported()", since that avoids negation at the caller:
if (10bit_tags_unsupported(a, b) ||
10bit_tags_unsupported(b, a))
map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
Good suggestion. add a pci_ prefix.
if (pci_10bit_tags_unsupported(a, b) ||
pci_10bit_tags_unsupported(b, a))
map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
This treats both directions as equally important. I don't know P2PDMA
very well, but that doesn't seem like it would necessarily be the
case. I would think a common case would be device A doing DMA to B,
but B *not* doing DMA to A. So can you tell which direction you're
setting up here, and can you take advantage of any asymmetry, e.g., by
enabling 10-bit tags in the direction that supports it even if the
other direction does not?
Documentation/driver-api/pci/p2pdma.rst
* Provider - A driver which provides or publishes P2P resources like
memory or doorbell registers to other drivers.
* Client - A driver which makes use of a resource by setting up a
DMA transaction to or from it.
So we may just check as below.
if (10bit_tags_unsupported(client, provider, verbose)
map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
@Logan What's your opinion?
Thanks,
Dongdong
.
