x86/prot-key: Split PKRU infrastructure out of asm/processor.h

asm/processor.h is in desperate need of splitting up, and protection key
functionality in only used in the emulator and pagewalk.  Introduce a new
asm/prot-key.h and move the relevant content over.

Rename the PKRU_* constants to drop the user part and to use the architectural
terminology.

Drop the read_pkru_{ad,wd}() helpers entirely.  The pkru infix is about to
become wrong, and the sole user is shorter and easier to follow without the
helpers.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/cpu/common.c

@@ -11,6 +11,7 @@
 #include <asm/io.h>
 #include <asm/mpspec.h>
 #include <asm/apic.h>
+#include <asm/prot-key.h>
 #include <asm/random.h>
 #include <asm/setup.h>
 #include <asm/shstk.h>

xen/arch/x86/include/asm/processor.h

@@ -374,44 +374,6 @@ static always_inline void set_in_cr4 (unsigned long mask)
     write_cr4(read_cr4() | mask);
 }
 
-static inline unsigned int rdpkru(void)
-{
-    unsigned int pkru;
-
-    asm volatile (".byte 0x0f,0x01,0xee"
-        : "=a" (pkru) : "c" (0) : "dx");
-
-    return pkru;
-}
-
-static inline void wrpkru(unsigned int pkru)
-{
-    asm volatile ( ".byte 0x0f, 0x01, 0xef"
-                   :: "a" (pkru), "d" (0), "c" (0) );
-}
-
-/* Macros for PKRU domain */
-#define PKRU_READ  (0)
-#define PKRU_WRITE (1)
-#define PKRU_ATTRS (2)
-
-/*
- * PKRU defines 32 bits, there are 16 domains and 2 attribute bits per
- * domain in pkru, pkeys is index to a defined domain, so the value of
- * pte_pkeys * PKRU_ATTRS + R/W is offset of a defined domain attribute.
- */
-static inline bool_t read_pkru_ad(uint32_t pkru, unsigned int pkey)
-{
-    ASSERT(pkey < 16);
-    return (pkru >> (pkey * PKRU_ATTRS + PKRU_READ)) & 1;
-}
-
-static inline bool_t read_pkru_wd(uint32_t pkru, unsigned int pkey)
-{
-    ASSERT(pkey < 16);
-    return (pkru >> (pkey * PKRU_ATTRS + PKRU_WRITE)) & 1;
-}
-
 static always_inline void __monitor(const void *eax, unsigned long ecx,
                                     unsigned long edx)
 {

xen/arch/x86/include/asm/prot-key.h

@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2021-2022 Citrix Systems Ltd.
+ */
+#ifndef ASM_PROT_KEY_H
+#define ASM_PROT_KEY_H
+
+#include <xen/types.h>
+
+#define PKEY_AD 1 /* Access Disable */
+#define PKEY_WD 2 /* Write Disable */
+
+#define PKEY_WIDTH 2 /* Two bits per protection key */
+
+static inline uint32_t rdpkru(void)
+{
+    uint32_t pkru;
+
+    asm volatile ( ".byte 0x0f,0x01,0xee"
+                   : "=a" (pkru) : "c" (0) : "dx" );
+
+    return pkru;
+}
+
+static inline void wrpkru(uint32_t pkru)
+{
+    asm volatile ( ".byte 0x0f,0x01,0xef"
+                   :: "a" (pkru), "d" (0), "c" (0) );
+}
+
+#endif /* ASM_PROT_KEY_H */

xen/arch/x86/mm/guest_walk.c

@@ -26,7 +26,9 @@
 #include <xen/paging.h>
 #include <xen/domain_page.h>
 #include <xen/sched.h>
+
 #include <asm/page.h>
+#include <asm/prot-key.h>
 #include <asm/guest_pt.h>
 #include <asm/hvm/emulate.h>
 
@@ -413,10 +415,11 @@ guest_walk_tables(const struct vcpu *v, struct p2m_domain *p2m,
          guest_pku_enabled(v) )
     {
         unsigned int pkey = guest_l1e_get_pkey(gw->l1e);
-        unsigned int pkru = rdpkru();
+        unsigned int pkr = rdpkru();
+        unsigned int pk_ar = (pkr >> (pkey * PKEY_WIDTH)) & (PKEY_AD | PKEY_WD);
 
-        if ( read_pkru_ad(pkru, pkey) ||
-             ((walk & PFEC_write_access) && read_pkru_wd(pkru, pkey) &&
+        if ( (pk_ar & PKEY_AD) ||
+             ((walk & PFEC_write_access) && (pk_ar & PKEY_WD) &&
               ((walk & PFEC_user_mode) || guest_wp_enabled(v))) )
         {
             gw->pfec |= PFEC_prot_key;

xen/arch/x86/x86_emulate.c

@@ -12,8 +12,10 @@
 #include <xen/domain_page.h>
 #include <xen/err.h>
 #include <xen/event.h>
+
 #include <asm/x86_emulate.h>
 #include <asm/processor.h> /* current_cpu_info */
+#include <asm/prot-key.h>
 #include <asm/xstate.h>
 #include <asm/amd.h> /* cpu_has_amd_erratum() */
 #include <asm/debugreg.h>