[PATCH 5/5] x86/sgx: Rename vm_prot_bits as max_vm_flags

[Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>]

vm_prot_bits is very bad and misleading name for the field in struct
sgx_encl_page. What the field contains exactly is not @prot of
mprotect() but the *maximum* VM flags for the VMA that contains the
given enclave page.

Thus, the only viable name for the field is max_vm_flags. In functions
that also pass VM flags the parameter name is renamed from vm_prot_bits
to vm_flags.

To summarize, this commit makes two improvements to clarify the
permission handling:

1. Changes the name to match better the contents.
2. Uses naming to differentiate the field inside the struct and
   the parameter passed to functions.

Cc: Sean Christopherson <sean.j.christpherson@intel.com>
Cc: Shay Katz-zamir <shay.katz-zamir@intel.com>
Cc: Serge Ayoun <serge.ayoun@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 arch/x86/kernel/cpu/sgx/driver/ioctl.c |  2 +-
 arch/x86/kernel/cpu/sgx/encl.c         | 14 +++++++-------
 arch/x86/kernel/cpu/sgx/encl.h         |  4 ++--
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/driver/ioctl.c b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
index 2415dcb20a6e..b61e06daad6e 100644
--- a/arch/x86/kernel/cpu/sgx/driver/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
@@ -261,7 +261,7 @@ static struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
 	encl_page->encl = encl;
 
 	/* Calculate maximum of the VM flags for the page. */
-	encl_page->vm_prot_bits = calc_vm_prot_bits(prot, 0);
+	encl_page->max_vm_flags = calc_vm_prot_bits(prot, 0);
 
 	ret = radix_tree_insert(&encl->page_tree, PFN_DOWN(encl_page->desc),
 				encl_page);
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index a20d498e9dcd..890eacb45a80 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -292,25 +292,25 @@ static unsigned int sgx_vma_fault(struct vm_fault *vmf)
  * @encl:		an enclave
  * @start:		lower bound of the address range, inclusive
  * @end:		upper bound of the address range, exclusive
- * @vm_prot_bits:	requested protections of the address range
+ * @vm_flags:		requested VM flags for the address range
  *
  * Iterate through the enclave pages contained within [@start, @end) to verify
- * the permissions requested by @vm_prot_bits do not exceed that of any enclave
- * page to be mapped.  Page addresses that do not have an associated enclave
- * page are interpreted to zero permissions.
+ * the the VM flags do not exceed that of any enclave page to be mapped. Page
+ * addresses that do not have an associated enclave page are interpreted to zero
+ * permissions.
  *
  * Return:
  *   0 on success,
  *   -EACCES if VMA permissions exceed enclave page permissions
  */
 int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start,
-		     unsigned long end, unsigned long vm_prot_bits)
+		     unsigned long end, unsigned long vm_flags)
 {
 	unsigned long idx, idx_start, idx_end;
 	struct sgx_encl_page *page;
 
 	/* PROT_NONE always succeeds. */
-	if (!vm_prot_bits)
+	if (!vm_flags)
 		return 0;
 
 	idx_start = PFN_DOWN(start);
@@ -321,7 +321,7 @@ int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start,
 		page = radix_tree_lookup(&encl->page_tree, idx);
 		mutex_unlock(&encl->lock);
 
-		if (!page || (~page->vm_prot_bits & vm_prot_bits))
+		if (!page || (~page->max_vm_flags & vm_flags))
 			return -EACCES;
 	}
 
diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
index d3a1687ed84c..0e28b784a8c5 100644
--- a/arch/x86/kernel/cpu/sgx/encl.h
+++ b/arch/x86/kernel/cpu/sgx/encl.h
@@ -44,7 +44,7 @@ enum sgx_encl_page_desc {
 
 struct sgx_encl_page {
 	unsigned long desc;
-	unsigned long vm_prot_bits;
+	unsigned long max_vm_flags;
 	struct sgx_epc_page *epc_page;
 	struct sgx_va_page *va_page;
 	struct sgx_encl *encl;
@@ -134,6 +134,6 @@ void sgx_free_va_slot(struct sgx_va_page *va_page, unsigned int offset);
 bool sgx_va_page_full(struct sgx_va_page *va_page);
 
 int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start,
-		     unsigned long end, unsigned long vm_prot_bits);
+		     unsigned long end, unsigned long vm_flags);
 
 #endif /* _X86_ENCL_H */
-- 
2.20.1