On Wed, 29 Mar 2017 17:00:39 +0200
Joerg Roedel <j...@8bytes.org> wrote:
> From: Joerg Roedel <jroe...@suse.de>
>
> When booting into a kexec kernel with intel_iommu=off, and
> the previous kernel had intel_iommu=on, the IOMMU hardware
> is still enabled and gets not disabled by the new kernel.
>
> This causes the boot to fail because DMA is blocked by the
> hardware. Disable the IOMMUs when we find it enabled in the
> kexec kernel and boot with intel_iommu=off.
>
> Signed-off-by: Joerg Roedel <jroe...@suse.de>
> ---
> drivers/iommu/intel-iommu.c | 18 +++++++++++++++++-
> 1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index d412a31..1662288 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -4730,6 +4730,15 @@ static int intel_iommu_cpu_dead(unsigned int
> cpu) return 0;
> }
>
> +static void intel_disable_iommus(void)
> +{
> + struct intel_iommu *iommu = NULL;
> + struct dmar_drhd_unit *drhd;
> +
> + for_each_iommu(iommu, drhd)
> + iommu_disable_translation(iommu);
should we also disable IR here? i.e.
iommu_disable_irq_remapping(iommu);
> +}
> +
> static inline struct intel_iommu *dev_to_intel_iommu(struct device
> *dev) {
> return container_of(dev, struct intel_iommu, iommu.dev);
> @@ -4840,8 +4849,15 @@ int __init intel_iommu_init(void)
> goto out_free_dmar;
> }
>
> - if (no_iommu || dmar_disabled)
> + if (no_iommu || dmar_disabled) {
> + /*
> + * Make sure the IOMMUs are switched off, even when
> we
> + * boot into a kexec kernel and the previous kernel
> left
> + * them enabled
> + */
> + intel_disable_iommus();
> goto out_free_dmar;
> + }
>
> if (list_empty(&dmar_rmrr_units))
> pr_info("No RMRR found\n");
[Jacob Pan]
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