lkml.org 
[lkml]   [2019]   [Nov]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] intel-iommu: Turn off translations at shutdown
From
Date
Hi,

On 11/8/19 4:59 AM, Deepa Dinamani wrote:
> The intel-iommu driver assumes that the iommu state is
> cleaned up at the start of the new kernel.
> But, when we try to kexec boot something other than the
> Linux kernel, the cleanup cannot be relied upon.
> Hence, cleanup before we go down for reboot.
>
> Keeping the cleanup at initialization also, in case BIOS
> leaves the IOMMU enabled.
>
> I considered turning off iommu only during kexec reboot,
> but a clean shutdown seems always a good idea. But if
> someone wants to make it conditional, we can do that.
>
> Tested that before, the info message
> 'DMAR: Translation was enabled for <iommu> but we are not in kdump mode'
> would be reported for each iommu. The message will not appear when the
> DMA-remapping is not enabled on entry to the kernel.
>
> Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
> ---
> drivers/iommu/intel-iommu.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index fe8097078669..f0636b263722 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -4764,6 +4764,26 @@ static void intel_disable_iommus(void)
> iommu_disable_translation(iommu);
> }
>
> +static void intel_iommu_shutdown(void)
> +{
> + struct dmar_drhd_unit *drhd;
> + struct intel_iommu *iommu = NULL;
> +
> + if (no_iommu || dmar_disabled)
> + return;
> +
> + down_write(&dmar_global_lock);
> +
> + /* Disable PMRs explicitly here. */
> + for_each_iommu(iommu, drhd)
> + iommu_disable_protect_mem_regions(iommu);
> +
> + /* Make sure the IOMMUs are switched off */
> + intel_disable_iommus();
> +
> + up_write(&dmar_global_lock);
> +}
> +
> static inline struct intel_iommu *dev_to_intel_iommu(struct device *dev)
> {
> struct iommu_device *iommu_dev = dev_to_iommu_device(dev);
> @@ -5013,6 +5033,8 @@ int __init intel_iommu_init(void)
> }
> up_write(&dmar_global_lock);
>
> + x86_platform.iommu_shutdown = intel_iommu_shutdown;

How about moving it to detect_intel_iommu() in drivers/iommu/dmar.c? And
make sure that it's included with CONFIG_X86_64.

Best regards,
baolu

> +
> #if defined(CONFIG_X86) && defined(CONFIG_SWIOTLB)
> /*
> * If the system has no untrusted device or the user has decided
>

\
 
 \ /
  Last update: 2019-11-08 04:09    [W:0.184 / U:0.156 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site