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Subject[PATCH 5.5 004/150] iommu/vt-d: Do deferred attachment in iommu_need_mapping()
Date
From: Joerg Roedel <jroedel@suse.de>

commit a11bfde9c77df1fd350ea27169ab921f511bf5d0 upstream.

The attachment of deferred devices needs to happen before the check
whether the device is identity mapped or not. Otherwise the check will
return wrong results, cause warnings boot failures in kdump kernels, like

WARNING: CPU: 0 PID: 318 at ../drivers/iommu/intel-iommu.c:592 domain_get_iommu+0x61/0x70

[...]

Call Trace:
__intel_map_single+0x55/0x190
intel_alloc_coherent+0xac/0x110
dmam_alloc_attrs+0x50/0xa0
ahci_port_start+0xfb/0x1f0 [libahci]
ata_host_start.part.39+0x104/0x1e0 [libata]

With the earlier check the kdump boot succeeds and a crashdump is written.

Fixes: 1ee0186b9a12 ("iommu/vt-d: Refactor find_domain() helper")
Cc: stable@vger.kernel.org # v5.5
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/iommu/intel-iommu.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2452,9 +2452,6 @@ static void do_deferred_attach(struct de

static struct dmar_domain *deferred_attach_domain(struct device *dev)
{
- if (unlikely(attach_deferred(dev)))
- do_deferred_attach(dev);
-
return find_domain(dev);
}

@@ -3478,6 +3475,9 @@ static bool iommu_need_mapping(struct de
if (iommu_dummy(dev))
return false;

+ if (unlikely(attach_deferred(dev)))
+ do_deferred_attach(dev);
+
ret = identity_mapping(dev);
if (ret) {
u64 dma_mask = *dev->dma_mask;
@@ -3841,7 +3841,11 @@ bounce_map_single(struct device *dev, ph
int prot = 0;
int ret;

+ if (unlikely(attach_deferred(dev)))
+ do_deferred_attach(dev);
+
domain = deferred_attach_domain(dev);
+
if (WARN_ON(dir == DMA_NONE || !domain))
return DMA_MAPPING_ERROR;


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