x86/tdx: Refactor try_accept_one()

Rework try_accept_one() to return accepted size instead of modifying
'start' inside the helper. It makes 'start' in-only argument and
streamlines code on the caller side.

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20230606142637.5171-9-kirill.shutemov@linux.intel.com

diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index e6f4c27..0d5fe6e 100644 (file)
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -713,18 +713,18 @@ static bool tdx_cache_flush_required(void)
        return true;
 }
 
-static bool try_accept_one(phys_addr_t *start, unsigned long len,
-                         enum pg_level pg_level)
+static unsigned long try_accept_one(phys_addr_t start, unsigned long len,
+                                   enum pg_level pg_level)
 {
        unsigned long accept_size = page_level_size(pg_level);
        u64 tdcall_rcx;
        u8 page_size;
 
-       if (!IS_ALIGNED(*start, accept_size))
-               return false;
+       if (!IS_ALIGNED(start, accept_size))
+               return 0;
 
        if (len < accept_size)
-               return false;
+               return 0;
 
        /*
         * Pass the page physical address to the TDX module to accept the
@@ -743,15 +743,14 @@ static bool try_accept_one(phys_addr_t *start, unsigned long len,
                page_size = 2;
                break;
        default:
-               return false;
+               return 0;
        }
 
-       tdcall_rcx = *start | page_size;
+       tdcall_rcx = start | page_size;
        if (__tdx_module_call(TDX_ACCEPT_PAGE, tdcall_rcx, 0, 0, 0, NULL))
-               return false;
+               return 0;
 
-       *start += accept_size;
-       return true;
+       return accept_size;
 }
 
 /*
@@ -788,21 +787,22 @@ static bool tdx_enc_status_changed(unsigned long vaddr, int numpages, bool enc)
         */
        while (start < end) {
                unsigned long len = end - start;
+               unsigned long accept_size;
 
                /*
                 * Try larger accepts first. It gives chance to VMM to keep
-                * 1G/2M SEPT entries where possible and speeds up process by
-                * cutting number of hypercalls (if successful).
+                * 1G/2M Secure EPT entries where possible and speeds up
+                * process by cutting number of hypercalls (if successful).
                 */
 
-               if (try_accept_one(&start, len, PG_LEVEL_1G))
-                       continue;
-
-               if (try_accept_one(&start, len, PG_LEVEL_2M))
-                       continue;
-
-               if (!try_accept_one(&start, len, PG_LEVEL_4K))
+               accept_size = try_accept_one(start, len, PG_LEVEL_1G);
+               if (!accept_size)
+                       accept_size = try_accept_one(start, len, PG_LEVEL_2M);
+               if (!accept_size)
+                       accept_size = try_accept_one(start, len, PG_LEVEL_4K);
+               if (!accept_size)
                        return false;
+               start += accept_size;
        }
 
        return true;