* [PATCH 0/1] iommu/of: Fix request and enable ACS for of_iommu_configure
@ 2021-05-07 12:49 ` Wang Xingang
0 siblings, 0 replies; 8+ messages in thread
From: Wang Xingang @ 2021-05-07 12:49 UTC (permalink / raw)
To: will, joro
Cc: bhelgaas, gregkh, iommu, linux-kernel, linux-pci, xieyingtai,
wangxingang5
From: Xingang Wang <wangxingang5@huawei.com>
When request ACS in of_iommu_configure, the pci_acs_init procedure has
already been called. The pci device probe procedure is like the following:
pci_host_common_probe
pci_device_add
pci_acs_init
of_iommu_configure
pci_request_acs
The pci_request_acs() does not work because the pci_acs_init and
pci_enable_acs procedure has already finished, so the ACS is not
enabled as expected. Besides, the ACS is enabled only if IOMMU is
detected and the device is pci.
So this fix 6bf6c24720d33 ("iommu/of: Request ACS from the PCI core
when configuring IOMMU linkage"), add pci_enable_acs() and IOMMU check
to make sure ACS is enabled for the pci_device.
Xingang Wang (1):
iommu/of: Fix request and enable ACS for of_iommu_configure
drivers/iommu/of_iommu.c | 10 +++++++++-
drivers/pci/pci.c | 2 +-
include/linux/pci.h | 1 +
3 files changed, 11 insertions(+), 2 deletions(-)
--
2.19.1
^ permalink raw reply [flat|nested] 8+ messages in thread* [PATCH 0/1] iommu/of: Fix request and enable ACS for of_iommu_configure @ 2021-05-07 12:49 ` Wang Xingang 0 siblings, 0 replies; 8+ messages in thread From: Wang Xingang @ 2021-05-07 12:49 UTC (permalink / raw) To: will, joro Cc: xieyingtai, wangxingang5, gregkh, linux-kernel, iommu, linux-pci, bhelgaas From: Xingang Wang <wangxingang5@huawei.com> When request ACS in of_iommu_configure, the pci_acs_init procedure has already been called. The pci device probe procedure is like the following: pci_host_common_probe pci_device_add pci_acs_init of_iommu_configure pci_request_acs The pci_request_acs() does not work because the pci_acs_init and pci_enable_acs procedure has already finished, so the ACS is not enabled as expected. Besides, the ACS is enabled only if IOMMU is detected and the device is pci. So this fix 6bf6c24720d33 ("iommu/of: Request ACS from the PCI core when configuring IOMMU linkage"), add pci_enable_acs() and IOMMU check to make sure ACS is enabled for the pci_device. Xingang Wang (1): iommu/of: Fix request and enable ACS for of_iommu_configure drivers/iommu/of_iommu.c | 10 +++++++++- drivers/pci/pci.c | 2 +- include/linux/pci.h | 1 + 3 files changed, 11 insertions(+), 2 deletions(-) -- 2.19.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH 1/1] iommu/of: Fix request and enable ACS for of_iommu_configure 2021-05-07 12:49 ` Wang Xingang @ 2021-05-07 12:49 ` Wang Xingang -1 siblings, 0 replies; 8+ messages in thread From: Wang Xingang @ 2021-05-07 12:49 UTC (permalink / raw) To: will, joro Cc: bhelgaas, gregkh, iommu, linux-kernel, linux-pci, xieyingtai, wangxingang5 From: Xingang Wang <wangxingang5@huawei.com> When request ACS for PCI device in of_iommu_configure, the pci device has already been scanned and added with 'pci_acs_enable=0'. So the pci_request_acs() in current procedure does not work for enabling ACS. Besides, the ACS should be enabled only if there's an IOMMU in system. So this fix the call of pci_request_acs() and call pci_enable_acs() to make sure ACS is enabled for the pci_device. Fixes: 6bf6c24720d33 ("iommu/of: Request ACS from the PCI core when configuring IOMMU linkage") Signed-off-by: Xingang Wang <wangxingang5@huawei.com> --- drivers/iommu/of_iommu.c | 10 +++++++++- drivers/pci/pci.c | 2 +- include/linux/pci.h | 1 + 3 files changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c index a9d2df001149..dc621861ae72 100644 --- a/drivers/iommu/of_iommu.c +++ b/drivers/iommu/of_iommu.c @@ -205,7 +205,6 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, .np = master_np, }; - pci_request_acs(); err = pci_for_each_dma_alias(to_pci_dev(dev), of_pci_iommu_init, &info); } else { @@ -222,6 +221,15 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, /* The fwspec pointer changed, read it again */ fwspec = dev_iommu_fwspec_get(dev); ops = fwspec->ops; + + /* + * If we found an IOMMU and the device is pci, + * make sure we enable ACS. + */ + if (dev_is_pci(dev)) { + pci_request_acs(); + pci_enable_acs(to_pci_dev(dev)); + } } /* * If we have reason to believe the IOMMU driver missed the initial diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index b717680377a9..4e4f98ee2870 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -926,7 +926,7 @@ static void pci_std_enable_acs(struct pci_dev *dev) * pci_enable_acs - enable ACS if hardware support it * @dev: the PCI device */ -static void pci_enable_acs(struct pci_dev *dev) +void pci_enable_acs(struct pci_dev *dev) { if (!pci_acs_enable) goto disable_acs_redir; diff --git a/include/linux/pci.h b/include/linux/pci.h index c20211e59a57..e6a8bfbc9c98 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -2223,6 +2223,7 @@ static inline struct pci_dev *pcie_find_root_port(struct pci_dev *dev) } void pci_request_acs(void); +void pci_enable_acs(struct pci_dev *dev); bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags); bool pci_acs_path_enabled(struct pci_dev *start, struct pci_dev *end, u16 acs_flags); -- 2.19.1 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH 1/1] iommu/of: Fix request and enable ACS for of_iommu_configure @ 2021-05-07 12:49 ` Wang Xingang 0 siblings, 0 replies; 8+ messages in thread From: Wang Xingang @ 2021-05-07 12:49 UTC (permalink / raw) To: will, joro Cc: xieyingtai, wangxingang5, gregkh, linux-kernel, iommu, linux-pci, bhelgaas From: Xingang Wang <wangxingang5@huawei.com> When request ACS for PCI device in of_iommu_configure, the pci device has already been scanned and added with 'pci_acs_enable=0'. So the pci_request_acs() in current procedure does not work for enabling ACS. Besides, the ACS should be enabled only if there's an IOMMU in system. So this fix the call of pci_request_acs() and call pci_enable_acs() to make sure ACS is enabled for the pci_device. Fixes: 6bf6c24720d33 ("iommu/of: Request ACS from the PCI core when configuring IOMMU linkage") Signed-off-by: Xingang Wang <wangxingang5@huawei.com> --- drivers/iommu/of_iommu.c | 10 +++++++++- drivers/pci/pci.c | 2 +- include/linux/pci.h | 1 + 3 files changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c index a9d2df001149..dc621861ae72 100644 --- a/drivers/iommu/of_iommu.c +++ b/drivers/iommu/of_iommu.c @@ -205,7 +205,6 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, .np = master_np, }; - pci_request_acs(); err = pci_for_each_dma_alias(to_pci_dev(dev), of_pci_iommu_init, &info); } else { @@ -222,6 +221,15 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, /* The fwspec pointer changed, read it again */ fwspec = dev_iommu_fwspec_get(dev); ops = fwspec->ops; + + /* + * If we found an IOMMU and the device is pci, + * make sure we enable ACS. + */ + if (dev_is_pci(dev)) { + pci_request_acs(); + pci_enable_acs(to_pci_dev(dev)); + } } /* * If we have reason to believe the IOMMU driver missed the initial diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index b717680377a9..4e4f98ee2870 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -926,7 +926,7 @@ static void pci_std_enable_acs(struct pci_dev *dev) * pci_enable_acs - enable ACS if hardware support it * @dev: the PCI device */ -static void pci_enable_acs(struct pci_dev *dev) +void pci_enable_acs(struct pci_dev *dev) { if (!pci_acs_enable) goto disable_acs_redir; diff --git a/include/linux/pci.h b/include/linux/pci.h index c20211e59a57..e6a8bfbc9c98 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -2223,6 +2223,7 @@ static inline struct pci_dev *pcie_find_root_port(struct pci_dev *dev) } void pci_request_acs(void); +void pci_enable_acs(struct pci_dev *dev); bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags); bool pci_acs_path_enabled(struct pci_dev *start, struct pci_dev *end, u16 acs_flags); -- 2.19.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 1/1] iommu/of: Fix request and enable ACS for of_iommu_configure 2021-05-07 12:49 ` Wang Xingang @ 2021-05-07 21:14 ` Bjorn Helgaas -1 siblings, 0 replies; 8+ messages in thread From: Bjorn Helgaas @ 2021-05-07 21:14 UTC (permalink / raw) To: Wang Xingang Cc: will, joro, bhelgaas, gregkh, iommu, linux-kernel, linux-pci, xieyingtai On Fri, May 07, 2021 at 12:49:53PM +0000, Wang Xingang wrote: > From: Xingang Wang <wangxingang5@huawei.com> > > When request ACS for PCI device in of_iommu_configure, the pci device > has already been scanned and added with 'pci_acs_enable=0'. So the > pci_request_acs() in current procedure does not work for enabling ACS. > Besides, the ACS should be enabled only if there's an IOMMU in system. > So this fix the call of pci_request_acs() and call pci_enable_acs() to > make sure ACS is enabled for the pci_device. For consistency: s/of_iommu_configure/of_iommu_configure()/ s/pci device/PCI device/ s/pci_device/PCI device/ But I'm confused about what problem this fixes. On x86, I think we *do* set pci_acs_enable=1 in this path: start_kernel mm_init mem_init pci_iommu_alloc p->detect() detect_intel_iommu # IOMMU_INIT_POST(detect_intel_iommu) pci_request_acs pci_acs_enable = 1 before enumerating any PCI devices. But you mentioned pci_host_common_probe(), which I think is mostly used on non-x86 architectures, and I'm guessing those arches detect the IOMMU differently. So my question is, can we figure out how to detect IOMMUs the same way across all arches? > Fixes: 6bf6c24720d33 ("iommu/of: Request ACS from the PCI core when > configuring IOMMU linkage") > Signed-off-by: Xingang Wang <wangxingang5@huawei.com> > --- > drivers/iommu/of_iommu.c | 10 +++++++++- > drivers/pci/pci.c | 2 +- > include/linux/pci.h | 1 + > 3 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c > index a9d2df001149..dc621861ae72 100644 > --- a/drivers/iommu/of_iommu.c > +++ b/drivers/iommu/of_iommu.c > @@ -205,7 +205,6 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, > .np = master_np, > }; > > - pci_request_acs(); > err = pci_for_each_dma_alias(to_pci_dev(dev), > of_pci_iommu_init, &info); > } else { > @@ -222,6 +221,15 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, > /* The fwspec pointer changed, read it again */ > fwspec = dev_iommu_fwspec_get(dev); > ops = fwspec->ops; > + > + /* > + * If we found an IOMMU and the device is pci, > + * make sure we enable ACS. s/pci/PCI/ for consistency. > + */ > + if (dev_is_pci(dev)) { > + pci_request_acs(); > + pci_enable_acs(to_pci_dev(dev)); > + } > } > /* > * If we have reason to believe the IOMMU driver missed the initial > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index b717680377a9..4e4f98ee2870 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -926,7 +926,7 @@ static void pci_std_enable_acs(struct pci_dev *dev) > * pci_enable_acs - enable ACS if hardware support it > * @dev: the PCI device > */ > -static void pci_enable_acs(struct pci_dev *dev) > +void pci_enable_acs(struct pci_dev *dev) > { > if (!pci_acs_enable) > goto disable_acs_redir; > diff --git a/include/linux/pci.h b/include/linux/pci.h > index c20211e59a57..e6a8bfbc9c98 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -2223,6 +2223,7 @@ static inline struct pci_dev *pcie_find_root_port(struct pci_dev *dev) > } > > void pci_request_acs(void); > +void pci_enable_acs(struct pci_dev *dev); > bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags); > bool pci_acs_path_enabled(struct pci_dev *start, > struct pci_dev *end, u16 acs_flags); > -- > 2.19.1 > ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 1/1] iommu/of: Fix request and enable ACS for of_iommu_configure @ 2021-05-07 21:14 ` Bjorn Helgaas 0 siblings, 0 replies; 8+ messages in thread From: Bjorn Helgaas @ 2021-05-07 21:14 UTC (permalink / raw) To: Wang Xingang Cc: xieyingtai, gregkh, linux-kernel, iommu, linux-pci, bhelgaas, will On Fri, May 07, 2021 at 12:49:53PM +0000, Wang Xingang wrote: > From: Xingang Wang <wangxingang5@huawei.com> > > When request ACS for PCI device in of_iommu_configure, the pci device > has already been scanned and added with 'pci_acs_enable=0'. So the > pci_request_acs() in current procedure does not work for enabling ACS. > Besides, the ACS should be enabled only if there's an IOMMU in system. > So this fix the call of pci_request_acs() and call pci_enable_acs() to > make sure ACS is enabled for the pci_device. For consistency: s/of_iommu_configure/of_iommu_configure()/ s/pci device/PCI device/ s/pci_device/PCI device/ But I'm confused about what problem this fixes. On x86, I think we *do* set pci_acs_enable=1 in this path: start_kernel mm_init mem_init pci_iommu_alloc p->detect() detect_intel_iommu # IOMMU_INIT_POST(detect_intel_iommu) pci_request_acs pci_acs_enable = 1 before enumerating any PCI devices. But you mentioned pci_host_common_probe(), which I think is mostly used on non-x86 architectures, and I'm guessing those arches detect the IOMMU differently. So my question is, can we figure out how to detect IOMMUs the same way across all arches? > Fixes: 6bf6c24720d33 ("iommu/of: Request ACS from the PCI core when > configuring IOMMU linkage") > Signed-off-by: Xingang Wang <wangxingang5@huawei.com> > --- > drivers/iommu/of_iommu.c | 10 +++++++++- > drivers/pci/pci.c | 2 +- > include/linux/pci.h | 1 + > 3 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c > index a9d2df001149..dc621861ae72 100644 > --- a/drivers/iommu/of_iommu.c > +++ b/drivers/iommu/of_iommu.c > @@ -205,7 +205,6 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, > .np = master_np, > }; > > - pci_request_acs(); > err = pci_for_each_dma_alias(to_pci_dev(dev), > of_pci_iommu_init, &info); > } else { > @@ -222,6 +221,15 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, > /* The fwspec pointer changed, read it again */ > fwspec = dev_iommu_fwspec_get(dev); > ops = fwspec->ops; > + > + /* > + * If we found an IOMMU and the device is pci, > + * make sure we enable ACS. s/pci/PCI/ for consistency. > + */ > + if (dev_is_pci(dev)) { > + pci_request_acs(); > + pci_enable_acs(to_pci_dev(dev)); > + } > } > /* > * If we have reason to believe the IOMMU driver missed the initial > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index b717680377a9..4e4f98ee2870 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -926,7 +926,7 @@ static void pci_std_enable_acs(struct pci_dev *dev) > * pci_enable_acs - enable ACS if hardware support it > * @dev: the PCI device > */ > -static void pci_enable_acs(struct pci_dev *dev) > +void pci_enable_acs(struct pci_dev *dev) > { > if (!pci_acs_enable) > goto disable_acs_redir; > diff --git a/include/linux/pci.h b/include/linux/pci.h > index c20211e59a57..e6a8bfbc9c98 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -2223,6 +2223,7 @@ static inline struct pci_dev *pcie_find_root_port(struct pci_dev *dev) > } > > void pci_request_acs(void); > +void pci_enable_acs(struct pci_dev *dev); > bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags); > bool pci_acs_path_enabled(struct pci_dev *start, > struct pci_dev *end, u16 acs_flags); > -- > 2.19.1 > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 1/1] iommu/of: Fix request and enable ACS for of_iommu_configure 2021-05-07 21:14 ` Bjorn Helgaas @ 2021-05-08 1:32 ` Xingang Wang -1 siblings, 0 replies; 8+ messages in thread From: Xingang Wang @ 2021-05-08 1:32 UTC (permalink / raw) To: Bjorn Helgaas Cc: will, joro, bhelgaas, gregkh, iommu, linux-kernel, linux-pci, xieyingtai Hi Bjorn, On 2021/5/8 5:14, Bjorn Helgaas wrote: > On Fri, May 07, 2021 at 12:49:53PM +0000, Wang Xingang wrote: >> From: Xingang Wang <wangxingang5@huawei.com> >> >> When request ACS for PCI device in of_iommu_configure, the pci device >> has already been scanned and added with 'pci_acs_enable=0'. So the >> pci_request_acs() in current procedure does not work for enabling ACS. >> Besides, the ACS should be enabled only if there's an IOMMU in system. >> So this fix the call of pci_request_acs() and call pci_enable_acs() to >> make sure ACS is enabled for the pci_device. > > For consistency: > > s/of_iommu_configure/of_iommu_configure()/ > s/pci device/PCI device/ > s/pci_device/PCI device/ > > But I'm confused about what problem this fixes. On x86, I think we > *do* set pci_acs_enable=1 in this path: > > start_kernel > mm_init > mem_init > pci_iommu_alloc > p->detect() > detect_intel_iommu # IOMMU_INIT_POST(detect_intel_iommu) > pci_request_acs > pci_acs_enable = 1 > > before enumerating any PCI devices. > > But you mentioned pci_host_common_probe(), which I think is mostly > used on non-x86 architectures, and I'm guessing those arches detect > the IOMMU differently. > I am testing on an arm architecture, and found that the ACS is enabled properly when booting with ACPI. With ACPI enabled, x86 IOMMU is checked when parsing DMAR, arm SMMU is checked when parsing IORT. But when booting with devicetree, IOMMU is checked in of_iommu_configure, and the pci_request_acs() is late at this time. > So my question is, can we figure out how to detect IOMMUs the same way > across all arches? > Thanks. It would be better if there's a way to detect IOMMUs across all arches and both for ACPI and DT. >> Fixes: 6bf6c24720d33 ("iommu/of: Request ACS from the PCI core when >> configuring IOMMU linkage") >> Signed-off-by: Xingang Wang <wangxingang5@huawei.com> >> --- >> drivers/iommu/of_iommu.c | 10 +++++++++- >> drivers/pci/pci.c | 2 +- >> include/linux/pci.h | 1 + >> 3 files changed, 11 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c >> index a9d2df001149..dc621861ae72 100644 >> --- a/drivers/iommu/of_iommu.c >> +++ b/drivers/iommu/of_iommu.c >> @@ -205,7 +205,6 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, >> .np = master_np, >> }; >> >> - pci_request_acs(); >> err = pci_for_each_dma_alias(to_pci_dev(dev), >> of_pci_iommu_init, &info); >> } else { >> @@ -222,6 +221,15 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, >> /* The fwspec pointer changed, read it again */ >> fwspec = dev_iommu_fwspec_get(dev); >> ops = fwspec->ops; >> + >> + /* >> + * If we found an IOMMU and the device is pci, >> + * make sure we enable ACS. > > s/pci/PCI/ for consistency. > >> + */ >> + if (dev_is_pci(dev)) { >> + pci_request_acs(); >> + pci_enable_acs(to_pci_dev(dev)); >> + } >> } >> /* >> * If we have reason to believe the IOMMU driver missed the initial >> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c >> index b717680377a9..4e4f98ee2870 100644 >> --- a/drivers/pci/pci.c >> +++ b/drivers/pci/pci.c >> @@ -926,7 +926,7 @@ static void pci_std_enable_acs(struct pci_dev *dev) >> * pci_enable_acs - enable ACS if hardware support it >> * @dev: the PCI device >> */ >> -static void pci_enable_acs(struct pci_dev *dev) >> +void pci_enable_acs(struct pci_dev *dev) >> { >> if (!pci_acs_enable) >> goto disable_acs_redir; >> diff --git a/include/linux/pci.h b/include/linux/pci.h >> index c20211e59a57..e6a8bfbc9c98 100644 >> --- a/include/linux/pci.h >> +++ b/include/linux/pci.h >> @@ -2223,6 +2223,7 @@ static inline struct pci_dev *pcie_find_root_port(struct pci_dev *dev) >> } >> >> void pci_request_acs(void); >> +void pci_enable_acs(struct pci_dev *dev); >> bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags); >> bool pci_acs_path_enabled(struct pci_dev *start, >> struct pci_dev *end, u16 acs_flags); >> -- >> 2.19.1 >> > . > Thanks Xingang . ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 1/1] iommu/of: Fix request and enable ACS for of_iommu_configure @ 2021-05-08 1:32 ` Xingang Wang 0 siblings, 0 replies; 8+ messages in thread From: Xingang Wang @ 2021-05-08 1:32 UTC (permalink / raw) To: Bjorn Helgaas Cc: xieyingtai, gregkh, linux-kernel, iommu, linux-pci, bhelgaas, will Hi Bjorn, On 2021/5/8 5:14, Bjorn Helgaas wrote: > On Fri, May 07, 2021 at 12:49:53PM +0000, Wang Xingang wrote: >> From: Xingang Wang <wangxingang5@huawei.com> >> >> When request ACS for PCI device in of_iommu_configure, the pci device >> has already been scanned and added with 'pci_acs_enable=0'. So the >> pci_request_acs() in current procedure does not work for enabling ACS. >> Besides, the ACS should be enabled only if there's an IOMMU in system. >> So this fix the call of pci_request_acs() and call pci_enable_acs() to >> make sure ACS is enabled for the pci_device. > > For consistency: > > s/of_iommu_configure/of_iommu_configure()/ > s/pci device/PCI device/ > s/pci_device/PCI device/ > > But I'm confused about what problem this fixes. On x86, I think we > *do* set pci_acs_enable=1 in this path: > > start_kernel > mm_init > mem_init > pci_iommu_alloc > p->detect() > detect_intel_iommu # IOMMU_INIT_POST(detect_intel_iommu) > pci_request_acs > pci_acs_enable = 1 > > before enumerating any PCI devices. > > But you mentioned pci_host_common_probe(), which I think is mostly > used on non-x86 architectures, and I'm guessing those arches detect > the IOMMU differently. > I am testing on an arm architecture, and found that the ACS is enabled properly when booting with ACPI. With ACPI enabled, x86 IOMMU is checked when parsing DMAR, arm SMMU is checked when parsing IORT. But when booting with devicetree, IOMMU is checked in of_iommu_configure, and the pci_request_acs() is late at this time. > So my question is, can we figure out how to detect IOMMUs the same way > across all arches? > Thanks. It would be better if there's a way to detect IOMMUs across all arches and both for ACPI and DT. >> Fixes: 6bf6c24720d33 ("iommu/of: Request ACS from the PCI core when >> configuring IOMMU linkage") >> Signed-off-by: Xingang Wang <wangxingang5@huawei.com> >> --- >> drivers/iommu/of_iommu.c | 10 +++++++++- >> drivers/pci/pci.c | 2 +- >> include/linux/pci.h | 1 + >> 3 files changed, 11 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c >> index a9d2df001149..dc621861ae72 100644 >> --- a/drivers/iommu/of_iommu.c >> +++ b/drivers/iommu/of_iommu.c >> @@ -205,7 +205,6 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, >> .np = master_np, >> }; >> >> - pci_request_acs(); >> err = pci_for_each_dma_alias(to_pci_dev(dev), >> of_pci_iommu_init, &info); >> } else { >> @@ -222,6 +221,15 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, >> /* The fwspec pointer changed, read it again */ >> fwspec = dev_iommu_fwspec_get(dev); >> ops = fwspec->ops; >> + >> + /* >> + * If we found an IOMMU and the device is pci, >> + * make sure we enable ACS. > > s/pci/PCI/ for consistency. > >> + */ >> + if (dev_is_pci(dev)) { >> + pci_request_acs(); >> + pci_enable_acs(to_pci_dev(dev)); >> + } >> } >> /* >> * If we have reason to believe the IOMMU driver missed the initial >> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c >> index b717680377a9..4e4f98ee2870 100644 >> --- a/drivers/pci/pci.c >> +++ b/drivers/pci/pci.c >> @@ -926,7 +926,7 @@ static void pci_std_enable_acs(struct pci_dev *dev) >> * pci_enable_acs - enable ACS if hardware support it >> * @dev: the PCI device >> */ >> -static void pci_enable_acs(struct pci_dev *dev) >> +void pci_enable_acs(struct pci_dev *dev) >> { >> if (!pci_acs_enable) >> goto disable_acs_redir; >> diff --git a/include/linux/pci.h b/include/linux/pci.h >> index c20211e59a57..e6a8bfbc9c98 100644 >> --- a/include/linux/pci.h >> +++ b/include/linux/pci.h >> @@ -2223,6 +2223,7 @@ static inline struct pci_dev *pcie_find_root_port(struct pci_dev *dev) >> } >> >> void pci_request_acs(void); >> +void pci_enable_acs(struct pci_dev *dev); >> bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags); >> bool pci_acs_path_enabled(struct pci_dev *start, >> struct pci_dev *end, u16 acs_flags); >> -- >> 2.19.1 >> > . > Thanks Xingang . _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2021-05-08 1:33 UTC | newest] Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-05-07 12:49 [PATCH 0/1] iommu/of: Fix request and enable ACS for of_iommu_configure Wang Xingang 2021-05-07 12:49 ` Wang Xingang 2021-05-07 12:49 ` [PATCH 1/1] " Wang Xingang 2021-05-07 12:49 ` Wang Xingang 2021-05-07 21:14 ` Bjorn Helgaas 2021-05-07 21:14 ` Bjorn Helgaas 2021-05-08 1:32 ` Xingang Wang 2021-05-08 1:32 ` Xingang Wang
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