iommu/amd: Split device table initialization into irq and dma part

When the IOMMU is enabled very early (as with irq-remapping)
some devices are still in BIOS hand. When dma is blocked
early this can cause lots of IO_PAGE_FAULTs. So delay the
DMA initialization and do it right before the dma_ops are
initialized.
To be secure, block all interrupts by default when irq-remapping is
enabled in the system. They will be reenabled on demand
later. Without blocking interrupts by default devices can
issue arbitrary interrupts by sending special DMA packets to
the CPU that look like MSI messages. This is especially
dangerous when a device is assigned to a KVM guest because
the guest can then DoS the host.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 18 insertions, 1 deletions

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index f8a222b0ac3..8a7f1971d63 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -1381,7 +1381,7 @@ static int __init init_memory_definitions(struct acpi_table_header *table)
  * Init the device table to not allow DMA access for devices and
  * suppress all page faults
  */
-static void init_device_table(void)
+static void init_device_table_dma(void)
 {
 	u32 devid;
 
@@ -1391,6 +1391,17 @@ static void init_device_table(void)
 	}
 }
 
+static void init_device_table(void)
+{
+	u32 devid;
+
+	if (!amd_iommu_irq_remap)
+		return;
+
+	for (devid = 0; devid <= amd_iommu_last_bdf; ++devid)
+		set_dev_entry_bit(devid, DEV_ENTRY_IRQ_TBL_EN);
+}
+
 static void iommu_init_flags(struct amd_iommu *iommu)
 {
 	iommu->acpi_flags & IVHD_FLAG_HT_TUN_EN_MASK ?
@@ -1781,8 +1792,14 @@ static bool detect_ivrs(void)
 
 static int amd_iommu_init_dma(void)
 {
+	struct amd_iommu *iommu;
 	int ret;
 
+	init_device_table_dma();
+
+	for_each_iommu(iommu)
+		iommu_flush_all_caches(iommu);
+
 	if (iommu_pass_through)
 		ret = amd_iommu_init_passthrough();
 	else