Hi Logan Many thanks for your review. On 2021/7/24 0:25, Logan Gunthorpe wrote:
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()).
Will fix. Thanks, Dongdong
Logan .
