[RFC PATCH v2 21/22] pci: Allow encrypted MMIO mapping via sysfs

[Alexey Kardashevskiy <aik@amd.com>]

Add another resource#d_enc to allow mapping MMIO as
an encrypted/private region.

Unlike resourceN_wc, the node is added always as ability to
map MMIO as private depends on negotiation with the TSM which
happens quite late.

Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
---
 include/linux/pci.h     |  2 +-
 drivers/pci/mmap.c      | 11 +++++++-
 drivers/pci/pci-sysfs.c | 27 +++++++++++++++-----
 drivers/pci/proc.c      |  2 +-
 4 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 073f8f3aece8..862f63ef9bf9 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2129,7 +2129,7 @@ pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
  */
 int pci_mmap_resource_range(struct pci_dev *dev, int bar,
 			    struct vm_area_struct *vma,
-			    enum pci_mmap_state mmap_state, int write_combine);
+			    enum pci_mmap_state mmap_state, int write_combine, int enc);
 
 #ifndef arch_can_pci_mmap_wc
 #define arch_can_pci_mmap_wc()		0
diff --git a/drivers/pci/mmap.c b/drivers/pci/mmap.c
index 8da3347a95c4..4fd522aeb767 100644
--- a/drivers/pci/mmap.c
+++ b/drivers/pci/mmap.c
@@ -23,7 +23,7 @@ static const struct vm_operations_struct pci_phys_vm_ops = {
 
 int pci_mmap_resource_range(struct pci_dev *pdev, int bar,
 			    struct vm_area_struct *vma,
-			    enum pci_mmap_state mmap_state, int write_combine)
+			    enum pci_mmap_state mmap_state, int write_combine, int enc)
 {
 	unsigned long size;
 	int ret;
@@ -46,6 +46,15 @@ int pci_mmap_resource_range(struct pci_dev *pdev, int bar,
 
 	vma->vm_ops = &pci_phys_vm_ops;
 
+	/*
+	 * Calling remap_pfn_range() directly as io_remap_pfn_range()
+	 * enforces shared mapping.
+	 */
+	if (enc)
+		return remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
+				       vma->vm_end - vma->vm_start,
+				       vma->vm_page_prot);
+
 	return io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
 				  vma->vm_end - vma->vm_start,
 				  vma->vm_page_prot);
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 4136889011c9..7b03daa13879 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1062,7 +1062,7 @@ void pci_remove_legacy_files(struct pci_bus *b)
  * Use the regular PCI mapping routines to map a PCI resource into userspace.
  */
 static int pci_mmap_resource(struct kobject *kobj, const struct bin_attribute *attr,
-			     struct vm_area_struct *vma, int write_combine)
+			     struct vm_area_struct *vma, int write_combine, int enc)
 {
 	struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj));
 	int bar = (unsigned long)attr->private;
@@ -1082,21 +1082,28 @@ static int pci_mmap_resource(struct kobject *kobj, const struct bin_attribute *a
 
 	mmap_type = res->flags & IORESOURCE_MEM ? pci_mmap_mem : pci_mmap_io;
 
-	return pci_mmap_resource_range(pdev, bar, vma, mmap_type, write_combine);
+	return pci_mmap_resource_range(pdev, bar, vma, mmap_type, write_combine, enc);
 }
 
 static int pci_mmap_resource_uc(struct file *filp, struct kobject *kobj,
 				const struct bin_attribute *attr,
 				struct vm_area_struct *vma)
 {
-	return pci_mmap_resource(kobj, attr, vma, 0);
+	return pci_mmap_resource(kobj, attr, vma, 0, 0);
 }
 
 static int pci_mmap_resource_wc(struct file *filp, struct kobject *kobj,
 				const struct bin_attribute *attr,
 				struct vm_area_struct *vma)
 {
-	return pci_mmap_resource(kobj, attr, vma, 1);
+	return pci_mmap_resource(kobj, attr, vma, 1, 0);
+}
+
+static int pci_mmap_resource_enc(struct file *filp, struct kobject *kobj,
+				 const struct bin_attribute *attr,
+				 struct vm_area_struct *vma)
+{
+	return pci_mmap_resource(kobj, attr, vma, 0, 1);
 }
 
 static ssize_t pci_resource_io(struct file *filp, struct kobject *kobj,
@@ -1190,7 +1197,7 @@ static void pci_remove_resource_files(struct pci_dev *pdev)
 	}
 }
 
-static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
+static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine, int enc)
 {
 	/* allocate attribute structure, piggyback attribute name */
 	int name_len = write_combine ? 13 : 10;
@@ -1208,6 +1215,9 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
 	if (write_combine) {
 		sprintf(res_attr_name, "resource%d_wc", num);
 		res_attr->mmap = pci_mmap_resource_wc;
+	} else if (enc) {
+		sprintf(res_attr_name, "resource%d_enc", num);
+		res_attr->mmap = pci_mmap_resource_enc;
 	} else {
 		sprintf(res_attr_name, "resource%d", num);
 		if (pci_resource_flags(pdev, num) & IORESOURCE_IO) {
@@ -1264,11 +1274,14 @@ static int pci_create_resource_files(struct pci_dev *pdev)
 		if (!pci_resource_len(pdev, i))
 			continue;
 
-		retval = pci_create_attr(pdev, i, 0);
+		retval = pci_create_attr(pdev, i, 0, 0);
 		/* for prefetchable resources, create a WC mappable file */
 		if (!retval && arch_can_pci_mmap_wc() &&
 		    pdev->resource[i].flags & IORESOURCE_PREFETCH)
-			retval = pci_create_attr(pdev, i, 1);
+			retval = pci_create_attr(pdev, i, 1, 0);
+		/* Add node for private MMIO mapping */
+		if (!retval)
+			retval = pci_create_attr(pdev, i, 0, 1);
 		if (retval) {
 			pci_remove_resource_files(pdev);
 			return retval;
diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index f967709082d6..62992c8234f1 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -284,7 +284,7 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma)
 	/* Adjust vm_pgoff to be the offset within the resource */
 	vma->vm_pgoff -= start >> PAGE_SHIFT;
 	ret = pci_mmap_resource_range(dev, i, vma,
-				  fpriv->mmap_state, write_combine);
+				  fpriv->mmap_state, write_combine, 0);
 	if (ret < 0)
 		return ret;
 
-- 
2.47.1