On Tue, Jun 04, 2024 at 07:16:18PM +0300, Imre Deak wrote: > From: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > > In typical cases PCIe tunneling is needed to make the devices fully > usable for the host system. However, it poses a security issue because > they can also use DMA to access the host memory. We already have two > ways of preventing this, one an IOMMU that is enabled on recent systems > by default and the second is the "authorized" attribute under each > connected device that needs to be written by userspace before a PCIe > tunnel is created. This option adds one more by adding a Kconfig option, > which is enabled by default, that can be used to make kernel binaries > where PCIe tunneling is completely disabled. > > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > References: https://intel-gfx-ci.01.org/tree/drm-tip/Trybot_134314v1/bat-mtlp-9/boot0.txt > References: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/11261 > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> > --- > > The issue at the first References: link is a known false-positive lockdep issue > in the TBT/PCIe subsystem. After discussion with the TBT maintainer (Mika > Westerberg), the easiest solution for the iGFX CI is to disable the PCIe TBT > tunneling functionality which leads to the issue, as > > - It's not an important feature iGFX CI needs to test. > - There is no available solution (patch) yet to solve the lockdep issue. > > The feature could be re-enabled if needed once the lockdep issue is > solved upstream. This patch will be merged upstream, until that sending it > for core-for-CI. Acked-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> > > drivers/thunderbolt/Kconfig | 18 ++++++++++++++++++ > drivers/thunderbolt/tb.c | 2 +- > drivers/thunderbolt/tb.h | 9 +++++++++ > drivers/thunderbolt/tunnel.c | 8 ++++---- > drivers/thunderbolt/usb4.c | 2 +- > 5 files changed, 33 insertions(+), 6 deletions(-) > > diff --git a/drivers/thunderbolt/Kconfig b/drivers/thunderbolt/Kconfig > index 448fd2ec8f6e2..facf2e684c022 100644 > --- a/drivers/thunderbolt/Kconfig > +++ b/drivers/thunderbolt/Kconfig > @@ -18,6 +18,24 @@ menuconfig USB4 > > if USB4 > > +config USB4_PCIE_TUNNELING > + bool "Allow PCI Express tunneling over USB4 fabric" > + depends on PCI > + default y > + help > + USB4 and Thunderbolt devices typically include PCIe switch > + with a number of PCIe endpoints such as USB host controllers, > + GPUs and network adapters. These are made available to the > + host system through PCIe tunneling. These can use DMA and > + therefore have access to the host memory which is typically > + guarded by an IOMMU. This option allows disabling PCIe > + tunneling completely. > + > + For devices to be usable it is recommended to say Y here. > + > + Note this only works with systems that use Software Based > + Connection Manager (this is most USB4 hosts). > + > config USB4_DEBUGFS_WRITE > bool "Enable write by debugfs to configuration spaces (DANGEROUS)" > help > diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c > index 10e719dd837ce..7d71ff3f82c13 100644 > --- a/drivers/thunderbolt/tb.c > +++ b/drivers/thunderbolt/tb.c > @@ -3181,7 +3181,7 @@ struct tb *tb_probe(struct tb_nhi *nhi) > if (!tb) > return NULL; > > - if (tb_acpi_may_tunnel_pcie()) > + if (tb_may_tunnel_pcie()) > tb->security_level = TB_SECURITY_USER; > else > tb->security_level = TB_SECURITY_NOPCIE; > diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h > index 18aae4ccaed59..22fad8a9679ae 100644 > --- a/drivers/thunderbolt/tb.h > +++ b/drivers/thunderbolt/tb.h > @@ -1436,6 +1436,15 @@ static inline int tb_acpi_power_on_retimers(struct tb_port *port) { return 0; } > static inline int tb_acpi_power_off_retimers(struct tb_port *port) { return 0; } > #endif > > +static inline bool tb_may_tunnel_pcie(void) > +{ > +#ifdef CONFIG_USB4_PCIE_TUNNELING > + return tb_acpi_may_tunnel_pcie(); > +#else > + return false; > +#endif > +} > + > #ifdef CONFIG_DEBUG_FS > void tb_debugfs_init(void); > void tb_debugfs_exit(void); > diff --git a/drivers/thunderbolt/tunnel.c b/drivers/thunderbolt/tunnel.c > index 41cf6378ad251..7c8397c135ba9 100644 > --- a/drivers/thunderbolt/tunnel.c > +++ b/drivers/thunderbolt/tunnel.c > @@ -101,7 +101,7 @@ static unsigned int tb_available_credits(const struct tb_port *port, > size_t ndp; > > usb3 = tb_acpi_may_tunnel_usb3() ? sw->max_usb3_credits : 0; > - pcie = tb_acpi_may_tunnel_pcie() ? sw->max_pcie_credits : 0; > + pcie = tb_may_tunnel_pcie() ? sw->max_pcie_credits : 0; > > if (tb_acpi_is_xdomain_allowed()) { > spare = min_not_zero(sw->max_dma_credits, dma_credits); > @@ -426,7 +426,7 @@ bool tb_tunnel_reserved_pci(struct tb_port *port, int *reserved_up, > if (WARN_ON_ONCE(!port->remote)) > return false; > > - if (!tb_acpi_may_tunnel_pcie()) > + if (!tb_may_tunnel_pcie()) > return false; > > if (tb_port_get_link_generation(port) < 4) > @@ -1510,7 +1510,7 @@ static unsigned int tb_dma_available_credits(const struct tb_port *port) > int credits; > > credits = tb_available_credits(port, NULL); > - if (tb_acpi_may_tunnel_pcie()) > + if (tb_may_tunnel_pcie()) > credits -= sw->max_pcie_credits; > credits -= port->dma_credits; > > @@ -1821,7 +1821,7 @@ static int tb_usb3_consumed_bandwidth(struct tb_tunnel *tunnel, > int *consumed_up, int *consumed_down) > { > struct tb_port *port = tb_upstream_port(tunnel->dst_port->sw); > - int pcie_weight = tb_acpi_may_tunnel_pcie() ? TB_PCI_WEIGHT : 0; > + int pcie_weight = tb_may_tunnel_pcie() ? TB_PCI_WEIGHT : 0; > > /* > * PCIe tunneling, if enabled, affects the USB3 bandwidth so > diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c > index de480bf2a53de..cacc7bec19eb4 100644 > --- a/drivers/thunderbolt/usb4.c > +++ b/drivers/thunderbolt/usb4.c > @@ -282,7 +282,7 @@ int usb4_switch_setup(struct tb_switch *sw) > * Only enable PCIe tunneling if the parent router supports it > * and it is not disabled. > */ > - if (tb_acpi_may_tunnel_pcie() && > + if (tb_may_tunnel_pcie() && > tb_switch_find_port(parent, TB_TYPE_PCIE_DOWN)) { > val |= ROUTER_CS_5_PTO; > /* > -- > 2.43.3 >
