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Date: Sat, 24 Jul 2021 18:36:08 +0800 From: Dongdong Liu <liudongdong3@...wei.com> To: Logan Gunthorpe <logang@...tatee.com>, <helgaas@...nel.org>, <hch@...radead.org>, <kw@...ux.com>, <linux-pci@...r.kernel.org>, <rajur@...lsio.com>, <hverkuil-cisco@...all.nl> CC: <linux-media@...r.kernel.org>, <netdev@...r.kernel.org> Subject: Re: [PATCH V6 8/8] PCI/P2PDMA: Add a 10-bit tag check in P2PDMA 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@...wei.com> >> --- >> 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 > . >
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