Messages in this thread Patch in this message | | | Subject | Re: [PATCH] iommu/vt-d: Handle hotplug devices' default identity mapping setting | From | Lu Baolu <> | Date | Fri, 22 Feb 2019 13:06:47 +0800 |
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Hi,
On 2/22/19 10:44 AM, James Dong wrote: > 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/0000\: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.
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?
> > 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 <xmdong@google.com> > Reported-by: Jis Ben <jisben@google.com> > --- > 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)); > + } > +
I am not sure about whether this is a good place to fix this problem before Intel IOMMU driver switches to default domain.
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) Best regards, Lu Baolu
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