From: Kevin Mitchell <kevmitch@arista.com>
Date: Wed, 12 Jun 2019 21:52:03 +0000 (-0700)
Subject: iommu/amd: Make iommu_disable safer
X-Git-Tag: iommu-updates-v5.3^2~3
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=3ddbe913e55516d3e2165d43d4d5570761769878;p=users%2Fdwmw2%2Flinux.git

iommu/amd: Make iommu_disable safer

Make it safe to call iommu_disable during early init error conditions
before mmio_base is set, but after the struct amd_iommu has been added
to the amd_iommu_list. For example, this happens if firmware fails to
fill in mmio_phys in the ACPI table leading to a NULL pointer
dereference in iommu_feature_disable.

Fixes: 2c0ae1720c09c ('iommu/amd: Convert iommu initialization to state machine')
Signed-off-by: Kevin Mitchell <kevmitch@arista.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index f977df90d2a49..df144dc6d8aca 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -418,6 +418,9 @@ static void iommu_enable(struct amd_iommu *iommu)
 
 static void iommu_disable(struct amd_iommu *iommu)
 {
+	if (!iommu->mmio_base)
+		return;
+
 	/* Disable command buffer */
 	iommu_feature_disable(iommu, CONTROL_CMDBUF_EN);