On 2021-07-23 5:06 a.m., 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 saying to enable a ”pci=disable_10bit_tag=“ kernel
> parameter.
>
> Signed-off-by: Dongdong Liu <liudongdong3@xxxxxxxxxx>
> ---
> drivers/pci/p2pdma.c | 38 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 38 insertions(+)
>
> diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
> index 50cdde3..bd93840 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,
> @@ -541,6 +542,39 @@ calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client,
> return map_type;
> }
>
> +
> +static bool check_10bit_tags_vaild(struct pci_dev *a, struct pci_dev *b,
> + bool verbose)
> +{
> + bool req;
> + bool comp;
> + u16 ctl2;
> +
> + if (a->is_virtfn) {
> +#ifdef CONFIG_PCI_IOV
> + req = !!(a->physfn->sriov->ctrl &
> + PCI_SRIOV_CTRL_VF_10BIT_TAG_REQ_EN);
> +#endif
> + } else {
> + pcie_capability_read_word(a, PCI_EXP_DEVCTL2, &ctl2);
> + req = !!(ctl2 & PCI_EXP_DEVCTL2_10BIT_TAG_REQ_EN);
> + }
> +
> + comp = !!(b->pcie_devcap2 & PCI_EXP_DEVCAP2_10BIT_TAG_COMP);
> + if (req && (!comp)) {
> + if (verbose) {
> + pci_warn(a, "cannot be used for peer-to-peer DMA as 10-Bit Tag Requester enable is set in device (%s), but peer device (%s) does not support the 10-Bit Tag Completer\n",
> + pci_name(a), pci_name(b));
> +
> + pci_warn(a, "to disable 10-Bit Tag Requester for this device, add the kernel parameter: pci=disable_10bit_tag=%s\n",
> + pci_name(a));
> + }
> + return false;
> + }
> +
> + return true;
> +}
> +
> /**
> * pci_p2pdma_distance_many - Determine the cumulative distance between
> * a p2pdma provider and the clients in use.
> @@ -579,6 +613,10 @@ int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients,
> return -1;
> }
>
> + if (!check_10bit_tags_vaild(pci_client, provider, verbose) ||
> + !check_10bit_tags_vaild(provider, pci_client, verbose))
> + not_supported = true;
> +
This check needs to be done in calc_map_type_and_dist(). The mapping
type needs to be correctly stored in the xarray cache as other functions
rely on the cached value (and upcoming work will be calling
calc_map_type_and_dist() without pci_p2pdma_distance_many()).
Logan
