linux-kernel - [PATCH v3 4/5] iommu/amd - Expose the active IOMMU device table entries

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Date:   Wed, 14 Mar 2018 18:05:25 -0500
From:   Gary R Hook <gary.hook@....com>
To:     iommu@...ts.linux-foundation.org
Cc:     joro@...tes.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 4/5] iommu/amd - Expose the active IOMMU device table
 entries

Add a debugfs entry to dump the active device table entries from
the IOMMU's table. Active is determined by non-default values
in the first and second long words of the DTE. Aside from IOMMU
devices, this output should list every device reported by lspci.

Signed-off-by: Gary R Hook <gary.hook@....com>
---
 drivers/iommu/amd_iommu_debugfs.c |   60 +++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/drivers/iommu/amd_iommu_debugfs.c b/drivers/iommu/amd_iommu_debugfs.c
index d95428b1ef90..1d941c5329be 100644
--- a/drivers/iommu/amd_iommu_debugfs.c
+++ b/drivers/iommu/amd_iommu_debugfs.c
@@ -92,9 +92,62 @@ static const struct file_operations amd_iommu_debugfs_dtecount_ops = {
 	.write = NULL,
 };
 
+#define	MAX_PCI_ID	0xFFFF
+
+#define	PRINTDTE(i)	OSCNPRINTF("%02x:%02x:%x - %016llx %016llx %016llx %016llx\n", \
+				   PCI_BUS_NUM(i), PCI_SLOT(i), PCI_FUNC(i), \
+				   amd_iommu_dev_table[i].data[0], \
+				   amd_iommu_dev_table[i].data[1], \
+				   amd_iommu_dev_table[i].data[2], \
+				   amd_iommu_dev_table[i].data[3]);
+
+static ssize_t amd_iommu_debugfs_dte_read(struct file *filp,
+					  char __user *ubuf,
+					  size_t count, loff_t *offp)
+{
+	unsigned int obuflen;
+	unsigned int oboff = 0;
+	unsigned int istart, iend;
+	ssize_t ret;
+	u32 i, n;
+	char *obuf;
+
+	/* Count the number of valid entries in the device table */
+	istart = 0;
+	iend = MAX_PCI_ID;
+	n = amd_iommu_count_valid_dtes(istart, iend);
+	obuflen = n * 80;
+
+	obuf = kmalloc(OBUFLEN, GFP_KERNEL);
+	if (!obuf)
+		return -ENOMEM;
+
+	for (i = istart ; i <= iend ; i++)
+		if ((amd_iommu_dev_table[i].data[0] ^ 0x3)
+		     || amd_iommu_dev_table[i].data[1])
+			oboff += PRINTDTE(i);
+
+	ret = simple_read_from_buffer(ubuf, count, offp, obuf, oboff);
+	kfree(obuf);
+
+	return ret;
+}
+
+static const struct file_operations amd_iommu_debugfs_dte_ops = {
+	.owner = THIS_MODULE,
+	.open = simple_open,
+	.read = amd_iommu_debugfs_dte_read,
+	.write = NULL,
+};
+
 static char readmetext[] =
+"devicetable             Print active entries in the device table\n"
 "count                   Count of active devices\n"
 "verbose                 Provide additional descriptive text\n"
+"\n"
+"                        Dumping the Device Table\n"
+"The device table is scanned for entries that appear to be active. The\n"
+"default range is from 0 to 0xFFFF, and only active entries will be reported\n"
 "\n";
 
 static ssize_t amd_iommu_debugfs_readme_read(struct file *filp,
@@ -144,6 +197,13 @@ void amd_iommu_debugfs_setup(struct amd_iommu *iommu)
 	if (!d_verbose)
 		goto err;
 
+	/* Device Table Entries */
+	d_dte = debugfs_create_file("devicetable", 0400,
+				    iommu->debugfs_instance, iommu,
+				    &amd_iommu_debugfs_dte_ops);
+	if (!d_dte)
+		goto err;
+
 	d_dte = debugfs_create_file("count", 0400,
 				    iommu->debugfs_instance, iommu,
 				    &amd_iommu_debugfs_dtecount_ops);