RE: [PATCH] iommu/vt-d: Handle hotplug devices' default identity mapping setting
Baolu:
Yes, it is a generic issue for hotplug devices with current Intel IOMMU driver,
as reported in this thread as well.
The patch you provided does the job in our case. Please update this thread once
your patch is merged. Thanks.
Best Regards,
James
On 2/23/19 12:56 AM, Lu Baolu wrote
>
> @@ -4807,16 +4807,19 @@ static int device_notifier(struct notifier_block *nb,
> if (iommu_dummy(dev))
> return 0;
>
>- if (action != BUS_NOTIFY_REMOVED_DEVICE)
>- return 0;
>-
>- domain = find_domain(dev);
>- if (!domain)
>- return 0;
>+ if (action == BUS_NOTIFY_REMOVED_DEVICE) {
>+ domain = find_domain(dev);
>+ if (!domain)
>+ return 0;
>
>- dmar_remove_one_dev_info(dev);
>- if (!domain_type_is_vm_or_si(domain) && list_empty(&domain->devices))
>- domain_exit(domain);
>+ dmar_remove_one_dev_info(dev);
>+ if (!domain_type_is_vm_or_si(domain) &&
>+ list_empty(&domain->devices))
>+ domain_exit(domain);
>+ } else if (action == BUS_NOTIFY_ADD_DEVICE) {
>+ if (iommu_should_identity_map(dev, 1))
>+ domain_add_dev_info(si_domain, dev);
>+ }
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RE: [PATCH] iommu/vt-d: Handle hotplug devices' default identity mapping setting
Baolu:
The reproduction depends on devices. HW passthrough PCIe devices with default
identity map could have the issue. Make sure that messages like following came
out in dmesg and their mapping does not change after booting:
[ 10.167809] DMAR: Hardware identity mapping for device :30:00.0
[ 10.167823] DMAR: Hardware identity mapping for device :30:00.1
Devices which make following true could also be used for the experiment:
> static int iommu_should_identity_map(struct device *dev, int startup)
> {
> if ((iommu_identity_mapping & IDENTMAP_AZALIA) &&
IS_AZALIA(pdev))
> return 1;
> if ((iommu_identity_mapping & IDENTMAP_GFX) &&
IS_GFX_DEVICE(pdev))
> return 1;
Once they are up, remove them first by following command:
echo 1 > /sys/bus/pci/devices/\:03\:00.1/remove
Then trigger the hotplug device rescanning:
echo 1 > /sys/bus/pci/rescan
To provide an example of specific devices on the market, I need to try out.
Or, if it is fine with you, forcing a PCIe NIC card to be default hardware
passthrough by changing the intel-iommu.c is another easy way to reproduce
this issue.
Best Regards,
James
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RE: [PATCH] iommu/vt-d: Handle hotplug devices' default identity mapping setting
Baolu: Sorry that my last reply email seems not text format. Resend it now. Thanks for your comments and your patch. Please find below our responses to each of your comments: > What does "I/O operation won't work" exactly mean here? Do you see any > IOMMU fault message? Or, something doesn't work as expected? Yes, DMAR fault messages as following came out: [ 354.939896] DMAR: DMAR:[DMA Read] Request device [03:00.1]fault addr 1fdfe8 [ 354.939896] DMAR:[fault reason 02] Present bit in context entry is clear > Do you mind checking this? > > index 6ecdcf8fc8c0..f62f30bc1339 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -2632,6 +2632,9 @@ static struct dmar_domain > *find_or_alloc_domain(struct device *dev, int gaw) > goto out; > } > > + if (!iommu_should_identity_map(dev, 0)) > + return si_domain; > + > /* Allocate and initialize new domain for the device */ > domain = alloc_domain(0); > if (!domain) Tried this patch, and the same DMAR fault message came out. Guess it is because of the iommu code path for hotplug devices. If a hotplug device is rescanned after removal, iommu_bus_notifier will be called as part of the notifier chains to handle BUS_NOTIFY_ADD_DEVICE event. Along the code path, intel_iommu_ops->add_device() created an iommu group for this hotplug device, but failed to create an iommu domain because of the default domain type IOMMU_DOMAIN_IDENTITY imposed by current IOMMU command line option got declined by intel_iommu_ops->domain_alloc(). Since si_domain is type of "struct dmar_domain", which is platform dependent, it is hard to make this change in intel_iommu_ops->domain_alloc(). In your patch, function find_or_alloc_domain() is not in the code path of BUS_NOTIFY_ADD_DEVICE event notifier chain. Please let us know if your have more concerns and suggestions. Best Regards, James ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH] iommu/vt-d: Handle hotplug devices' default identity mapping setting
Baolu: Thanks for your comments and your patch. Please find below our responses to each of your comments: > What does "I/O operation won't work" exactly mean here? Do you see any > IOMMU fault message? Or, something doesn't work as expected? Yes, DMAR fault messages as following came out: [ 354.939896] DMAR: DMAR:[DMA Read] Request device [03:00.1]fault addr 1fdfe8 [ 354.939896] DMAR:[fault reason 02] Present bit in context entry is clear > Do you mind checking this? > > index 6ecdcf8fc8c0..f62f30bc1339 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -2632,6 +2632,9 @@ static struct dmar_domain > *find_or_alloc_domain(struct device *dev, int gaw) > goto out; > } > > + if (!iommu_should_identity_map(dev, 0)) > + return si_domain; > + > /* Allocate and initialize new domain for the device */ > domain = alloc_domain(0); > if (!domain) Tried this patch, and the same DMAR fault message came out. Guess it is because of the iommu code path for hotplug devices. If a hotplug device is rescanned after removal, iommu_bus_notifier will be called as part of the notifier chains to handle BUS_NOTIFY_ADD_DEVICE event. Along the code path, intel_iommu_ops->add_device() created an iommu group for this hotplug device, but failed to create an iommu domain because of the default domain type IOMMU_DOMAIN_IDENTITY imposed by current IOMMU command line option got declined by intel_iommu_ops->domain_alloc(). In your patch, function find_or_alloc_domain() is not even in the code path of BUS_NOTIFY_ADD_DEVICE event notifier chain. Please let us know if your have more concerns and suggestions. Best Regards, James On Thu, Feb 21, 2019 at 9:35 PM Lu Baolu wrote: > Hi > > On 2/22/19 1:06 PM, Lu Baolu wrote: > > > Do you mind checking this? > > > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > > index 6ecdcf8fc8c0..f62f30bc1339 100644 > > --- a/drivers/iommu/intel-iommu.c > > +++ b/drivers/iommu/intel-iommu.c > > @@ -2632,6 +2632,9 @@ static struct dmar_domain > > *find_or_alloc_domain(struct device *dev, int gaw) > > goto out; > > } > > > > + if (!iommu_should_identity_map(dev, 0)) > > + return si_domain; > > + > > /* Allocate and initialize new domain for the device */ > > domain = alloc_domain(0); > > if (!domain) > > Oops! This can't be compiled. Please try below instead if you'd like to. > Sorry about it. > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index 6ecdcf8fc8c0..b89f5ba6a3c8 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -174,6 +174,8 @@ static inline unsigned long virt_to_dma_pfn(void *p) > return page_to_dma_pfn(virt_to_page(p)); > } > > +static int iommu_should_identity_map(struct device *dev, int startup); > + > /* global iommu list, set NULL for ignored DMAR units */ > static struct intel_iommu **g_iommus; > > @@ -2632,6 +2634,9 @@ static struct dmar_domain > *find_or_alloc_domain(struct device *dev, int gaw) > goto out; > } > > + if (iommu_should_identity_map(dev, 0)) > + return si_domain; > + > /* Allocate and initialize new domain for the device */ > domain = alloc_domain(0); > if (!domain) > > Best regards, > Lu Baolu > > > ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
[PATCH] iommu/vt-d: Handle hotplug devices' default identity mapping setting
With specific Linux command line option such as "iommu=pt", some types
of hotplug devices will be assigned to the static 1:1 iommu domain by
default during kernel init.
If such a hotplug device is rescanned after being removed, for example,
with following sample commands:
echo 1 > /sys/bus/pci/devices/\:03\:00.1/remove
echo 1 > /sys/bus/pci/rescan
, an iommu group for this hotplug device will be added without attaching
it to the default static 1:1 domain. As a result, this device's I/O
operation won't work.
Keep hotplug devices with default static 1:1 iommu mapping in their default
domain after such hotplug devices are rescanned.
Signed-off-by: James Dong
Reported-by: Jis Ben
---
drivers/iommu/intel-iommu.c | 14 +-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 78188bf7e90d..4b02949e58ca 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5230,6 +5230,7 @@ static int intel_iommu_add_device(struct device *dev)
struct intel_iommu *iommu;
struct iommu_group *group;
u8 bus, devfn;
+ int ret = 0;
iommu = device_to_iommu(dev, &bus, &devfn);
if (!iommu)
@@ -5242,8 +5243,19 @@ static int intel_iommu_add_device(struct device *dev)
if (IS_ERR(group))
return PTR_ERR(group);
+ if (!iommu_group_default_domain(group) &&
+ !find_domain(dev) && iommu_should_identity_map(dev, 0)) {
+ ret = domain_add_dev_info(si_domain, dev);
+ if (!ret)
+ pr_info("identity mapping for device %s\n",
+ dev_name(dev));
+ else
+ pr_info("identity mapping failed (%d) for device %s\n",
+ ret, dev_name(dev));
+ }
+
iommu_group_put(group);
- return 0;
+ return ret;
}
static void intel_iommu_remove_device(struct device *dev)
--
2.21.0.rc0.258.g878e2cd30e-goog
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