linux-kernel - Re: amd kdump failure with iommu=nopt

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Date:   Thu, 14 May 2020 17:40:20 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        Tom Murphy <murphyt7@....ie>
Subject: Re: amd kdump failure with iommu=nopt

On Thu, May 14, 2020 at 05:36:23PM +0200, Joerg Roedel wrote:
> This commit also removes the deferred attach of the device to its new
> domain. Does the attached diff fix the problem for you?
> +static int __iommu_attach_device_no_defer(struct iommu_domain *domain,
> +					  struct device *dev)
> +{
>  	if (unlikely(domain->ops->attach_dev == NULL))
>  		return -ENODEV;
>  
>  	ret = domain->ops->attach_dev(domain, dev);
>  	if (!ret)
>  		trace_attach_device_to_domain(dev);
> +
>  	return ret;
>  }

Sorry, this didn't compile, here is an updated version that actually
compiles:


diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 4050569188be..f54ebb964271 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1889,13 +1889,19 @@ void iommu_domain_free(struct iommu_domain *domain)
 }
 EXPORT_SYMBOL_GPL(iommu_domain_free);
 
-static int __iommu_attach_device(struct iommu_domain *domain,
-				 struct device *dev)
+static bool __iommu_is_attach_deferred(struct iommu_domain *domain,
+				       struct device *dev)
+{
+	if (!domain->ops->is_attach_deferred)
+		return false;
+
+	return domain->ops->is_attach_deferred(domain, dev);
+}
+
+static int __iommu_attach_device_no_defer(struct iommu_domain *domain,
+					  struct device *dev)
 {
 	int ret;
-	if ((domain->ops->is_attach_deferred != NULL) &&
-	    domain->ops->is_attach_deferred(domain, dev))
-		return 0;
 
 	if (unlikely(domain->ops->attach_dev == NULL))
 		return -ENODEV;
@@ -1903,9 +1909,19 @@ static int __iommu_attach_device(struct iommu_domain *domain,
 	ret = domain->ops->attach_dev(domain, dev);
 	if (!ret)
 		trace_attach_device_to_domain(dev);
+
 	return ret;
 }
 
+static int __iommu_attach_device(struct iommu_domain *domain,
+				 struct device *dev)
+{
+	if (__iommu_is_attach_deferred(domain, dev))
+		return 0;
+
+	return __iommu_attach_device_no_defer(domain, dev);
+}
+
 int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
 {
 	struct iommu_group *group;
@@ -2023,7 +2039,12 @@ EXPORT_SYMBOL_GPL(iommu_get_domain_for_dev);
  */
 struct iommu_domain *iommu_get_dma_domain(struct device *dev)
 {
-	return dev->iommu_group->default_domain;
+	struct iommu_domain *domain = dev->iommu_group->default_domain;
+
+	if (__iommu_is_attach_deferred(domain, dev))
+		__iommu_attach_device_no_defer(domain, dev);
+
+	return domain;
 }
 
 /*