On 10/06/15 17:30, Michael S. Tsirkin wrote:
On Tue, Oct 06, 2015 at 11:37:59AM +0300, Vlad Zolotarov wrote:Bus mastering is easily enabled from the user space (taken from DPDK code): static int pci_uio_set_bus_master(int dev_fd) { uint16_t reg; int ret; ret = pread(dev_fd, ®, sizeof(reg), PCI_COMMAND); if (ret != sizeof(reg)) { RTE_LOG(ERR, EAL, "Cannot read command from PCI config space!\n"); return -1; } /* return if bus mastering is already on */ if (reg & PCI_COMMAND_MASTER) return 0; reg |= PCI_COMMAND_MASTER; ret = pwrite(dev_fd, ®, sizeof(reg), PCI_COMMAND); if (ret != sizeof(reg)) { RTE_LOG(ERR, EAL, "Cannot write command to PCI config space!\n"); return -1; } return 0; } So, this is a non-issue. ;)There might be valid reasons for DPDK to do this, e.g. if using VFIO.
Michael, I'm afraid u are missing the main point here - the code above destroys all your long arguments. U can't possibly prevent the root-user from enabling the device bus mastering. And as me and other people on this thread have already mentioned MSI and MSI-X device configuration is controlled from the device BAR, thus may not be prevented too.
I'm guessing it doesn't enable MSI though, does it?
Again, enabling MSI is a matter of a trivial patch configuring device registers on the device BAR.
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