x86/amd-iommu: Reenable AMD IOMMU if it's mysteriously vanished over suspend

AMD's reference BIOS code had a bug that could result in the
firmware failing to reenable the iommu on resume. It
transpires that this causes certain less than desirable
behaviour when it comes to PCI accesses, to whit them ending
up somewhere near Bristol when the more desirable outcome
was Edinburgh. Sadness ensues, perhaps along with filesystem
corruption.  Let's make sure that it gets turned back on,
and that we restore its configuration so decisions it makes
bear some resemblance to those made by reasonable people
rather than crack-addled lemurs who spent all your DMA on
Thunderbird.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 15 insertions, 6 deletions

diff --git a/arch/x86/include/asm/amd_iommu_types.h b/arch/x86/include/asm/amd_iommu_types.h
index 08616180deaf..bdd20c8891e8 100644
--- a/arch/x86/include/asm/amd_iommu_types.h
+++ b/arch/x86/include/asm/amd_iommu_types.h
@@ -416,13 +416,22 @@ struct amd_iommu {
 	struct dma_ops_domain *default_dom;
 
 	/*
-	 * This array is required to work around a potential BIOS bug.
-	 * The BIOS may miss to restore parts of the PCI configuration
-	 * space when the system resumes from S3. The result is that the
-	 * IOMMU does not execute commands anymore which leads to system
-	 * failure.
+	 * We can't rely on the BIOS to restore all values on reinit, so we
+	 * need to stash them
 	 */
-	u32 cache_cfg[4];
+
+	/* The iommu BAR */
+	u32 stored_addr_lo;
+	u32 stored_addr_hi;
+
+	/*
+	 * Each iommu has 6 l1s, each of which is documented as having 0x12
+	 * registers
+	 */
+	u32 stored_l1[6][0x12];
+
+	/* The l2 indirect registers */
+	u32 stored_l2[0x83];
 };
 
 /*