[PATCH 2/2] iommu: dmar -- reserve mmio space used by IOMMU

[Donald Dutile <ddutile-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

Intel-iommu initialization doesn't currently reserve the memory used
for the IOMMU registers. This can allow the pci resource allocator
to assign a device BAR to the same address as the IOMMU registers.
This can cause some not so nice side affects when the driver
ioremap's that region.

Introduced two helper functions to map & unmap the IOMMU registers
as well as simplify the init and exit paths.

Signed-off-by: Donald Dutile <ddutile-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 drivers/iommu/dmar.c        | 111 +++++++++++++++++++++++++++++++++-----------
 include/linux/intel-iommu.h |   2 +
 2 files changed, 86 insertions(+), 27 deletions(-)

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 1e5a10d..9ab6ebf 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -570,14 +570,89 @@ int __init detect_intel_iommu(void)
 }
 
 
+static void unmap_iommu(struct intel_iommu *iommu)
+{
+	iounmap(iommu->reg);
+	release_mem_region(iommu->reg_phys, iommu->reg_size);
+}
+
+/**
+ * map_iommu: map the iommu's registers
+ * @iommu: the iommu to map
+ * @phys_addr: the physical address of the base resgister
+ * 
+ * Memory map the iommu's registers.  Start w/ a single page, and
+ * possibly expand if that turns out to be insufficent.  
+ */
+static int map_iommu(struct intel_iommu *iommu, u64 phys_addr)
+{
+	int map_size, err=0;
+
+	iommu->reg_phys = phys_addr;
+	iommu->reg_size = VTD_PAGE_SIZE;
+
+	if (!request_mem_region(iommu->reg_phys, iommu->reg_size, iommu->name)) {
+		pr_err("IOMMU: can't reserve memory\n");
+		err = -EBUSY;
+		goto out;
+	}
+
+	iommu->reg = ioremap(iommu->reg_phys, iommu->reg_size);
+	if (!iommu->reg) {
+		pr_err("IOMMU: can't map the region\n");
+		err = -ENOMEM;
+		goto release;
+	}
+
+	iommu->cap = dmar_readq(iommu->reg + DMAR_CAP_REG);
+	iommu->ecap = dmar_readq(iommu->reg + DMAR_ECAP_REG);
+
+	if (iommu->cap == (uint64_t)-1 && iommu->ecap == (uint64_t)-1) {
+		err = -EINVAL;
+		warn_invalid_dmar(phys_addr, " returns all ones");
+		goto unmap;
+	}
+
+	/* the registers might be more than one page */
+	map_size = max_t(int, ecap_max_iotlb_offset(iommu->ecap),
+			 cap_max_fault_reg_offset(iommu->cap));
+	map_size = VTD_PAGE_ALIGN(map_size);
+	if (map_size > iommu->reg_size) {
+		iounmap(iommu->reg);
+		release_mem_region(iommu->reg_phys, iommu->reg_size);
+		iommu->reg_size = map_size;
+		if (!request_mem_region(iommu->reg_phys, iommu->reg_size,
+					iommu->name)) {
+			pr_err("IOMMU: can't reserve memory\n");
+			err = -EBUSY;
+			goto out;
+		}
+		iommu->reg = ioremap(iommu->reg_phys, iommu->reg_size);
+		if (!iommu->reg) {
+			pr_err("IOMMU: can't map the region\n");
+			err = -ENOMEM;
+			goto release;
+		}
+	}
+	err = 0;
+	goto out;
+
+unmap:
+	iounmap(iommu->reg);
+release:
+	release_mem_region(iommu->reg_phys, iommu->reg_size);
+out:
+	return err;
+}
+
 int alloc_iommu(struct dmar_drhd_unit *drhd)
 {
 	struct intel_iommu *iommu;
-	int map_size;
 	u32 ver;
 	static int iommu_allocated = 0;
 	int agaw = 0;
 	int msagaw = 0;
+	int err;
 
 	if (!drhd->reg_base_addr) {
 		warn_invalid_dmar(0, "");
@@ -591,19 +666,13 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
 	iommu->seq_id = iommu_allocated++;
 	sprintf (iommu->name, "dmar%d", iommu->seq_id);
 
-	iommu->reg = ioremap(drhd->reg_base_addr, VTD_PAGE_SIZE);
-	if (!iommu->reg) {
-		pr_err("IOMMU: can't map the region\n");
+	err = map_iommu(iommu, drhd->reg_base_addr);
+	if (err) {
+		pr_err("IOMMU: failed to map %s\n", iommu->name);
 		goto error;
 	}
-	iommu->cap = dmar_readq(iommu->reg + DMAR_CAP_REG);
-	iommu->ecap = dmar_readq(iommu->reg + DMAR_ECAP_REG);
-
-	if (iommu->cap == (uint64_t)-1 && iommu->ecap == (uint64_t)-1) {
-		warn_invalid_dmar(drhd->reg_base_addr, " returns all ones");
-		goto err_unmap;
-	}
 
+	err = -EINVAL;
 	agaw = iommu_calculate_agaw(iommu);
 	if (agaw < 0) {
 		pr_err("Cannot get a valid agaw for iommu (seq_id = %d)\n",
@@ -621,19 +690,6 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
 
 	iommu->node = -1;
 
-	/* the registers might be more than one page */
-	map_size = max_t(int, ecap_max_iotlb_offset(iommu->ecap),
-		cap_max_fault_reg_offset(iommu->cap));
-	map_size = VTD_PAGE_ALIGN(map_size);
-	if (map_size > VTD_PAGE_SIZE) {
-		iounmap(iommu->reg);
-		iommu->reg = ioremap(drhd->reg_base_addr, map_size);
-		if (!iommu->reg) {
-			pr_err("IOMMU: can't map the region\n");
-			goto error;
-		}
-	}
-
 	ver = readl(iommu->reg + DMAR_VER_REG);
 	pr_info("IOMMU %d: reg_base_addr %llx ver %d:%d cap %llx ecap %llx\n",
 		iommu->seq_id,
@@ -648,10 +704,10 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
 	return 0;
 
  err_unmap:
-	iounmap(iommu->reg);
+	unmap_iommu(iommu);
  error:
 	kfree(iommu);
-	return -1;
+	return err;
 }
 
 void free_iommu(struct intel_iommu *iommu)
@@ -662,7 +718,8 @@ void free_iommu(struct intel_iommu *iommu)
 	free_dmar_iommu(iommu);
 
 	if (iommu->reg)
-		iounmap(iommu->reg);
+		unmap_iommu(iommu);
+
 	kfree(iommu);
 }
 
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index e6ca56d..78e2ada 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -308,6 +308,8 @@ enum {
 
 struct intel_iommu {
 	void __iomem	*reg; /* Pointer to hardware regs, virtual addr */
+	u64 		reg_phys; /* physical address of hw register set */
+	u64		reg_size; /* size of hw register set */
 	u64		cap;
 	u64		ecap;
 	u32		gcmd; /* Holds TE, EAFL. Don't need SRTP, SFL, WBF */
-- 
1.7.10.2.552.gaa3bb87