Hi Bjorn, On Tue, Jul 14, 2020 at 1:15 PM Rajat Jain wrote: > The ACS "Translation Blocking" bit blocks the translated addresses from > the devices. We don't expect such traffic from devices unless ATS is > enabled on them. A device sending such traffic without ATS enabled, > indicates malicious intent, and thus should be blocked. > > Enable PCI_ACS_TB by default for all devices, and it stays enabled until > atleast one of the devices downstream wants to enable ATS. It gets > disabled to enable ATS on a device downstream it, and then gets enabled > back on once all the downstream devices don't need ATS. > > Signed-off-by: Rajat Jain > Just checking to see if you got a chance to look at this V5 patch. Thanks & Best Regards, Rajat > --- > Note that I'm ignoring the devices that require quirks to enable or > disable ACS, instead of using the standard way for ACS configuration. > The reason is that it would require adding yet another quirk table or > quirk function pointer, that I don't know how to implement for those > devices, and will neither have the devices to test that code. > > v5: Enable TB and disable ATS for all devices on boot. Disable TB later > only if needed to enable ATS on downstream devices. > v4: Add braces to avoid warning from kernel robot > print warning for only external-facing devices. > v3: print warning if ACS_TB not supported on external-facing/untrusted > ports. > Minor code comments fixes. > v2: Commit log change > > drivers/pci/ats.c | 5 ++++ > drivers/pci/pci.c | 57 +++++++++++++++++++++++++++++++++++++++++++++ > drivers/pci/pci.h | 2 ++ > drivers/pci/probe.c | 2 +- > include/linux/pci.h | 2 ++ > 5 files changed, 67 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c > index b761c1f72f67..e2ea9083f30f 100644 > --- a/drivers/pci/ats.c > +++ b/drivers/pci/ats.c > @@ -28,6 +28,9 @@ void pci_ats_init(struct pci_dev *dev) > return; > > dev->ats_cap = pos; > + > + dev->ats_enabled = 1; /* To avoid WARN_ON from pci_disable_ats() */ > + pci_disable_ats(dev); > } > > /** > @@ -82,6 +85,7 @@ int pci_enable_ats(struct pci_dev *dev, int ps) > } > pci_write_config_word(dev, dev->ats_cap + PCI_ATS_CTRL, ctrl); > > + pci_disable_acs_trans_blocking(dev); > dev->ats_enabled = 1; > return 0; > } > @@ -102,6 +106,7 @@ void pci_disable_ats(struct pci_dev *dev) > ctrl &= ~PCI_ATS_CTRL_ENABLE; > pci_write_config_word(dev, dev->ats_cap + PCI_ATS_CTRL, ctrl); > > + pci_enable_acs_trans_blocking(dev); > dev->ats_enabled = 0; > } > EXPORT_SYMBOL_GPL(pci_disable_ats); > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 73a862782214..614e3c1e8c56 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -876,6 +876,9 @@ static void pci_std_enable_acs(struct pci_dev *dev) > /* Upstream Forwarding */ > ctrl |= (cap & PCI_ACS_UF); > > + /* Translation Blocking */ > + ctrl |= (cap & PCI_ACS_TB); > + > pci_write_config_word(dev, pos + PCI_ACS_CTRL, ctrl); > } > > @@ -904,6 +907,60 @@ static void pci_enable_acs(struct pci_dev *dev) > pci_disable_acs_redir(dev); > } > > +void pci_disable_acs_trans_blocking(struct pci_dev *pdev) > +{ > + u16 cap, ctrl, pos; > + struct pci_dev *dev; > + > + if (!pci_acs_enable) > + return; > + > + for (dev = pdev; dev; dev = pci_upstream_bridge(pdev)) { > + > + pos = dev->acs_cap; > + if (!pos) > + continue; > + > + /* > + * Disable translation blocking when first downstream > + * device that needs it (for ATS) wants to enable ATS > + */ > + if (++dev->ats_dependencies == 1) { > + pci_read_config_word(dev, pos + PCI_ACS_CAP, &cap); > + pci_read_config_word(dev, pos + PCI_ACS_CTRL, > &ctrl); > + ctrl &= ~(cap & PCI_ACS_TB); > + pci_write_config_word(dev, pos + PCI_ACS_CTRL, > ctrl); > + } > + } > +} > + > +void pci_enable_acs_trans_blocking(struct pci_dev *pdev) > +{ > + u16 cap, ctrl, pos; > + struct pci_dev *dev; > + > + if (!pci_acs_enable) > + return; > + > + for (dev = pdev; dev; dev = pci_upstream_bridge(pdev)) { > + > + pos = dev->acs_cap; > + if (!pos) > + continue; > + > + /* > + * Enable translation blocking when last downstream device > + * that depends on it (for ATS), doesn't need ATS anymore > + */ > + if (--dev->ats_dependencies == 0) { > + pci_read_config_word(dev, pos + PCI_ACS_CAP, &cap); > + pci_read_config_word(dev, pos + PCI_ACS_CTRL, > &ctrl); > + ctrl |= (cap & PCI_ACS_TB); > + pci_write_config_word(dev, pos + PCI_ACS_CTRL, > ctrl); > + } > + } > +} > + > /** > * pci_restore_bars - restore a device's BAR values (e.g. after wake-up) > * @dev: PCI device to have its BARs restored > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h > index 12fb79fbe29d..f5d8ecb6ba96 100644 > --- a/drivers/pci/pci.h > +++ b/drivers/pci/pci.h > @@ -552,6 +552,8 @@ static inline int > pci_dev_specific_disable_acs_redir(struct pci_dev *dev) > return -ENOTTY; > } > #endif > +void pci_disable_acs_trans_blocking(struct pci_dev *dev); > +void pci_enable_acs_trans_blocking(struct pci_dev *dev); > > /* PCI error reporting and recovery */ > pci_ers_result_t pcie_do_recovery(struct pci_dev *dev, > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > index 8c40c00413e7..e2ff3a94e621 100644 > --- a/drivers/pci/probe.c > +++ b/drivers/pci/probe.c > @@ -2387,10 +2387,10 @@ static void pci_init_capabilities(struct pci_dev > *dev) > pci_vpd_init(dev); /* Vital Product Data */ > pci_configure_ari(dev); /* Alternative Routing-ID > Forwarding */ > pci_iov_init(dev); /* Single Root I/O Virtualization > */ > + pci_acs_init(dev); /* Access Control Services */ > pci_ats_init(dev); /* Address Translation Services */ > pci_pri_init(dev); /* Page Request Interface */ > pci_pasid_init(dev); /* Process Address Space ID */ > - pci_acs_init(dev); /* Access Control Services */ > pci_ptm_init(dev); /* Precision Time Measurement */ > pci_aer_init(dev); /* Advanced Error Reporting */ > pci_dpc_init(dev); /* Downstream Port Containment */ > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 7a40cd5caed0..31da4355f0fd 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -480,6 +480,8 @@ struct pci_dev { > u16 ats_cap; /* ATS Capability offset */ > u8 ats_stu; /* ATS Smallest Translation Unit */ > #endif > + /* Total number of downstream devices below a bridge that need ATS > */ > + u8 ats_dependencies; > #ifdef CONFIG_PCI_PRI > u16 pri_cap; /* PRI Capability offset */ > u32 pri_reqs_alloc; /* Number of PRI requests > allocated */ > -- > 2.27.0.389.gc38d7665816-goog > >