[PATCH] iommu/vt-d: quirk_ioat_snb_local_iommu: replace WARN_TAINT with pr_warn + add_taint

[PATCH] iommu/vt-d: quirk_ioat_snb_local_iommu: replace WARN_TAINT with pr_warn + add_taint

[Hans de Goede]

Quoting from the comment describing the WARN functions in
include/asm-generic/bug.h:

 * WARN(), WARN_ON(), WARN_ON_ONCE, and so on can be used to report
 * significant kernel issues that need prompt attention if they should ever
 * appear at runtime.
 *
 * Do not use these macros when checking for invalid external inputs

The (buggy) firmware tables which the dmar code was calling WARN_TAINT
for really are invalid external inputs. They are not under the kernel's
control and the issues in them cannot be fixed by a kernel update.
So logging a backtrace, which invites bug reports to be filed about this,
is not helpful.

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=701847
Fixes: 556ab45f9a77 ("ioat2: catch and recover from broken vtd configurations v6")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/iommu/intel-iommu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 3857a5cd1a75..8fd132f8e885 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4261,10 +4261,11 @@ static void quirk_ioat_snb_local_iommu(struct pci_dev *pdev)
 
 	/* we know that the this iommu should be at offset 0xa000 from vtbar */
 	drhd = dmar_find_matched_drhd_unit(pdev);
-	if (WARN_TAINT_ONCE(!drhd || drhd->reg_base_addr - vtbar != 0xa000,
-			    TAINT_FIRMWARE_WORKAROUND,
-			    "BIOS assigned incorrect VT-d unit for Intel(R) QuickData Technology device\n"))
+	if (!drhd || drhd->reg_base_addr - vtbar != 0xa000) {
+		pr_warn_once(FW_BUG "BIOS assigned incorrect VT-d unit for Intel(R) QuickData Technology device\n");
+		add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
 		pdev->dev.archdata.iommu = DUMMY_DEVICE_DOMAIN_INFO;
+	}
 }
 DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_IOAT_SNB, quirk_ioat_snb_local_iommu);
 
-- 
2.25.1

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Re: [PATCH] iommu/vt-d: quirk_ioat_snb_local_iommu: replace WARN_TAINT with pr_warn + add_taint

[Lu Baolu]

On 2020/3/10 2:25, Hans de Goede wrote:
> Quoting from the comment describing the WARN functions in
> include/asm-generic/bug.h:
> 
>   * WARN(), WARN_ON(), WARN_ON_ONCE, and so on can be used to report
>   * significant kernel issues that need prompt attention if they should ever
>   * appear at runtime.
>   *
>   * Do not use these macros when checking for invalid external inputs
> 
> The (buggy) firmware tables which the dmar code was calling WARN_TAINT
> for really are invalid external inputs. They are not under the kernel's
> control and the issues in them cannot be fixed by a kernel update.
> So logging a backtrace, which invites bug reports to be filed about this,
> is not helpful.
> 
> BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=701847
> Fixes: 556ab45f9a77 ("ioat2: catch and recover from broken vtd configurations v6")
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Acked-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu

> ---
>   drivers/iommu/intel-iommu.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 3857a5cd1a75..8fd132f8e885 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -4261,10 +4261,11 @@ static void quirk_ioat_snb_local_iommu(struct pci_dev *pdev)
>   
>   	/* we know that the this iommu should be at offset 0xa000 from vtbar */
>   	drhd = dmar_find_matched_drhd_unit(pdev);
> -	if (WARN_TAINT_ONCE(!drhd || drhd->reg_base_addr - vtbar != 0xa000,
> -			    TAINT_FIRMWARE_WORKAROUND,
> -			    "BIOS assigned incorrect VT-d unit for Intel(R) QuickData Technology device\n"))
> +	if (!drhd || drhd->reg_base_addr - vtbar != 0xa000) {
> +		pr_warn_once(FW_BUG "BIOS assigned incorrect VT-d unit for Intel(R) QuickData Technology device\n");
> +		add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
>   		pdev->dev.archdata.iommu = DUMMY_DEVICE_DOMAIN_INFO;
> +	}
>   }
>   DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_IOAT_SNB, quirk_ioat_snb_local_iommu);
>   
> 
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Re: [PATCH] iommu/vt-d: quirk_ioat_snb_local_iommu: replace WARN_TAINT with pr_warn + add_taint

[Joerg Roedel]

On Mon, Mar 09, 2020 at 07:25:10PM +0100, Hans de Goede wrote:
> Quoting from the comment describing the WARN functions in
> include/asm-generic/bug.h:
> 
>  * WARN(), WARN_ON(), WARN_ON_ONCE, and so on can be used to report
>  * significant kernel issues that need prompt attention if they should ever
>  * appear at runtime.
>  *
>  * Do not use these macros when checking for invalid external inputs
> 
> The (buggy) firmware tables which the dmar code was calling WARN_TAINT
> for really are invalid external inputs. They are not under the kernel's
> control and the issues in them cannot be fixed by a kernel update.
> So logging a backtrace, which invites bug reports to be filed about this,
> is not helpful.
> 
> BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=701847
> Fixes: 556ab45f9a77 ("ioat2: catch and recover from broken vtd configurations v6")
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  drivers/iommu/intel-iommu.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)

Applied, thanks.

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