[PATCH 4/6] amd-iommu: disable cmd buffer and evt logging before reprogramming iommu

[Joerg Roedel <joerg.roedel@amd.com>]

From: Chris Wright <chrisw@sous-sol.org>

The IOMMU spec states that IOMMU behavior may be undefined when the
IOMMU registers are rewritten while command or event buffer is enabled.
Disable them in IOMMU disable path.

Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
---
 arch/x86/kernel/amd_iommu_init.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index 575ca46..48a79b9 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -260,6 +260,14 @@ static void iommu_enable(struct amd_iommu *iommu)
 
 static void iommu_disable(struct amd_iommu *iommu)
 {
+	/* Disable command buffer */
+	iommu_feature_disable(iommu, CONTROL_CMDBUF_EN);
+
+	/* Disable event logging and event interrupts */
+	iommu_feature_disable(iommu, CONTROL_EVT_INT_EN);
+	iommu_feature_disable(iommu, CONTROL_EVT_LOG_EN);
+
+	/* Disable IOMMU hardware itself */
 	iommu_feature_disable(iommu, CONTROL_IOMMU_EN);
 }
 
@@ -1042,6 +1050,7 @@ static void enable_iommus(void)
 	struct amd_iommu *iommu;
 
 	for_each_iommu(iommu) {
+		iommu_disable(iommu);
 		iommu_set_device_table(iommu);
 		iommu_enable_command_buffer(iommu);
 		iommu_enable_event_buffer(iommu);
-- 
1.6.3.1