From: Robin Murphy <robin.murphy@arm.com> To: andreas.noever@gmail.com, michael.jamet@intel.com, mika.westerberg@linux.intel.com, YehezkelShB@gmail.com Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, mario.limonciello@amd.com, hch@lst.de Subject: [PATCH] thunderbolt: Stop using iommu_present() Date: Wed, 16 Mar 2022 11:25:51 +0000 [thread overview] Message-ID: <b4356b228db9cb88d12db6559e28714ce26e022e.1647429348.git.robin.murphy@arm.com> (raw) Even if an IOMMU might be present for some PCI segment in the system, that doesn't necessarily mean it provides translation for the device we care about. Furthermore, the presence or not of one firmware flag doesn't imply anything about the IOMMU driver's behaviour, which may still depend on other firmware properties and kernel options too. What actually matters is whether an IOMMU is enforcing protection for our device - regardless of whether that stemmed from firmware policy, kernel config, or user control - at the point we need to decide whether to authorise it. We can ascertain that generically by simply looking at whether we're currently attached to a translation domain or not. Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- I don't have the means to test this, but I'm at least 80% confident in my unpicking of the structures to retrieve the correct device... drivers/thunderbolt/domain.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/thunderbolt/domain.c b/drivers/thunderbolt/domain.c index 7018d959f775..5f5fc5f6a09b 100644 --- a/drivers/thunderbolt/domain.c +++ b/drivers/thunderbolt/domain.c @@ -257,13 +257,14 @@ static ssize_t iommu_dma_protection_show(struct device *dev, struct device_attribute *attr, char *buf) { + struct tb *tb = container_of(dev, struct tb, dev); + struct iommu_domain *iod = iommu_get_domain_for_dev(&tb->nhi->pdev->dev); /* * Kernel DMA protection is a feature where Thunderbolt security is * handled natively using IOMMU. It is enabled when IOMMU is - * enabled and ACPI DMAR table has DMAR_PLATFORM_OPT_IN set. + * enabled and actively enforcing translation. */ - return sprintf(buf, "%d\n", - iommu_present(&pci_bus_type) && dmar_platform_optin()); + return sprintf(buf, "%d\n", iod && iod->type != IOMMU_DOMAIN_IDENTITY); } static DEVICE_ATTR_RO(iommu_dma_protection); -- 2.28.0.dirty
WARNING: multiple messages have this Message-ID (diff)
From: Robin Murphy <robin.murphy@arm.com> To: andreas.noever@gmail.com, michael.jamet@intel.com, mika.westerberg@linux.intel.com, YehezkelShB@gmail.com Cc: iommu@lists.linux-foundation.org, linux-usb@vger.kernel.org, hch@lst.de, linux-kernel@vger.kernel.org, mario.limonciello@amd.com Subject: [PATCH] thunderbolt: Stop using iommu_present() Date: Wed, 16 Mar 2022 11:25:51 +0000 [thread overview] Message-ID: <b4356b228db9cb88d12db6559e28714ce26e022e.1647429348.git.robin.murphy@arm.com> (raw) Even if an IOMMU might be present for some PCI segment in the system, that doesn't necessarily mean it provides translation for the device we care about. Furthermore, the presence or not of one firmware flag doesn't imply anything about the IOMMU driver's behaviour, which may still depend on other firmware properties and kernel options too. What actually matters is whether an IOMMU is enforcing protection for our device - regardless of whether that stemmed from firmware policy, kernel config, or user control - at the point we need to decide whether to authorise it. We can ascertain that generically by simply looking at whether we're currently attached to a translation domain or not. Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- I don't have the means to test this, but I'm at least 80% confident in my unpicking of the structures to retrieve the correct device... drivers/thunderbolt/domain.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/thunderbolt/domain.c b/drivers/thunderbolt/domain.c index 7018d959f775..5f5fc5f6a09b 100644 --- a/drivers/thunderbolt/domain.c +++ b/drivers/thunderbolt/domain.c @@ -257,13 +257,14 @@ static ssize_t iommu_dma_protection_show(struct device *dev, struct device_attribute *attr, char *buf) { + struct tb *tb = container_of(dev, struct tb, dev); + struct iommu_domain *iod = iommu_get_domain_for_dev(&tb->nhi->pdev->dev); /* * Kernel DMA protection is a feature where Thunderbolt security is * handled natively using IOMMU. It is enabled when IOMMU is - * enabled and ACPI DMAR table has DMAR_PLATFORM_OPT_IN set. + * enabled and actively enforcing translation. */ - return sprintf(buf, "%d\n", - iommu_present(&pci_bus_type) && dmar_platform_optin()); + return sprintf(buf, "%d\n", iod && iod->type != IOMMU_DOMAIN_IDENTITY); } static DEVICE_ATTR_RO(iommu_dma_protection); -- 2.28.0.dirty _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
next reply other threads:[~2022-03-16 11:26 UTC|newest] Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-03-16 11:25 Robin Murphy [this message] 2022-03-16 11:25 ` [PATCH] thunderbolt: Stop using iommu_present() Robin Murphy 2022-03-16 12:45 ` Mika Westerberg 2022-03-16 12:45 ` Mika Westerberg 2022-03-16 14:49 ` Robin Murphy 2022-03-16 14:49 ` Robin Murphy 2022-03-16 17:18 ` Mika Westerberg 2022-03-16 17:18 ` Mika Westerberg 2022-03-16 17:24 ` Limonciello, Mario 2022-03-16 17:24 ` Limonciello, Mario via iommu 2022-03-16 17:37 ` Mika Westerberg 2022-03-16 17:37 ` Mika Westerberg 2022-03-16 17:49 ` Robin Murphy 2022-03-16 17:49 ` Robin Murphy 2022-03-16 17:53 ` Limonciello, Mario 2022-03-16 17:53 ` Limonciello, Mario via iommu 2022-03-16 18:08 ` Limonciello, Mario 2022-03-16 18:08 ` Limonciello, Mario via iommu 2022-03-16 18:22 ` Robin Murphy 2022-03-16 18:22 ` Robin Murphy 2022-03-16 18:34 ` Limonciello, Mario 2022-03-16 18:34 ` Limonciello, Mario via iommu 2022-03-16 19:17 ` Robin Murphy 2022-03-16 19:17 ` Robin Murphy 2022-03-16 19:25 ` Limonciello, Mario 2022-03-16 19:25 ` Limonciello, Mario via iommu 2022-03-17 8:08 ` Mika Westerberg 2022-03-17 8:08 ` Mika Westerberg 2022-03-17 13:42 ` Robin Murphy 2022-03-17 13:42 ` Robin Murphy 2022-03-17 14:21 ` Mika Westerberg 2022-03-17 14:21 ` Mika Westerberg 2022-03-17 6:30 ` Mika Westerberg 2022-03-17 6:30 ` Mika Westerberg 2022-03-16 14:49 ` Limonciello, Mario 2022-03-16 14:49 ` Limonciello, Mario via iommu
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