x86/intel: optional build of PSR support

Xen's implementation of PSR only supports Intel CPUs right now, hence it can be
made dependant on CONFIG_INTEL build option.
Since platform implementation is not limited to single vendor, intermediate
option CONFIG_X86_PSR introduced, which selected by CONFIG_INTEL.

When !X86_PSR then PSR-related sysctls XEN_SYSCTL_psr_cmt_op &
XEN_SYSCTL_psr_alloc are off as well.

Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@epam.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/Kconfig

@@ -231,6 +231,16 @@ config TBOOT
 
 	  If unsure, stay with the default.
 
+config X86_PSR
+	bool "Platform Shared Resource support" if EXPERT
+	default INTEL
+	help
+	  Support of Platform Shared Resource technology, which is basis for
+	  monitoring and control of resources like cache and memory bandwidth.
+	  See xl-psr documentation for details.
+
+	  If unsure, stay with the default.
+
 choice
 	prompt "Alignment of Xen image"
 	default XEN_ALIGN_2M if PV_SHIM_EXCLUSIVE

xen/arch/x86/Makefile

@@ -57,7 +57,7 @@ obj-y += pci.o
 obj-y += percpu.o
 obj-y += physdev.o
 obj-$(CONFIG_COMPAT) += x86_64/physdev.o
-obj-y += psr.o
+obj-$(CONFIG_X86_PSR) += psr.o
 obj-y += setup.o
 obj-y += shutdown.o
 obj-y += smp.o

xen/arch/x86/domctl.c

@@ -1195,6 +1195,7 @@ long arch_do_domctl(
     case XEN_DOMCTL_psr_alloc:
         switch ( domctl->u.psr_alloc.cmd )
         {
+#ifdef CONFIG_X86_PSR
         case XEN_DOMCTL_PSR_SET_L3_CBM:
             ret = psr_set_val(d, domctl->u.psr_alloc.target,
                               domctl->u.psr_alloc.data,
@@ -1257,6 +1258,8 @@ long arch_do_domctl(
 
 #undef domctl_psr_get_val
 
+#endif /* CONFIG_X86_PSR */
+
         default:
             ret = -EOPNOTSUPP;
             break;

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

@@ -69,12 +69,11 @@ extern struct psr_cmt *psr_cmt;
 
 static inline bool psr_cmt_enabled(void)
 {
-    return !!psr_cmt;
+    return IS_ENABLED(CONFIG_X86_PSR) && psr_cmt;
 }
 
 int psr_alloc_rmid(struct domain *d);
 void psr_free_rmid(struct domain *d);
-void psr_ctxt_switch_to(struct domain *d);
 
 int psr_get_info(unsigned int socket, enum psr_type type,
                  uint32_t data[], unsigned int array_len);
@@ -83,8 +82,15 @@ int psr_get_val(struct domain *d, unsigned int socket,
 int psr_set_val(struct domain *d, unsigned int socket,
                 uint64_t new_val, enum psr_type type);
 
+#ifdef CONFIG_X86_PSR
+void psr_ctxt_switch_to(struct domain *d);
 void psr_domain_init(struct domain *d);
 void psr_domain_free(struct domain *d);
+#else
+static inline void psr_ctxt_switch_to(struct domain *d) {}
+static inline void psr_domain_init(struct domain *d) {}
+static inline void psr_domain_free(struct domain *d) {}
+#endif
 
 #endif /* __ASM_PSR_H__ */
 

xen/arch/x86/sysctl.c

@@ -225,10 +225,11 @@ long arch_do_sysctl(
 
     case XEN_SYSCTL_psr_alloc:
     {
-        uint32_t data[PSR_INFO_ARRAY_SIZE] = { };
+        uint32_t __maybe_unused data[PSR_INFO_ARRAY_SIZE] = { };
 
         switch ( sysctl->u.psr_alloc.cmd )
         {
+#ifdef CONFIG_X86_PSR
         case XEN_SYSCTL_PSR_get_l3_info:
             ret = psr_get_info(sysctl->u.psr_alloc.target,
                                PSR_TYPE_L3_CBM, data, ARRAY_SIZE(data));
@@ -279,6 +280,7 @@ long arch_do_sysctl(
             if ( __copy_field_to_guest(u_sysctl, sysctl, u.psr_alloc) )
                 ret = -EFAULT;
             break;
+#endif /* CONFIG_X86_PSR */
 
         default:
             ret = -EOPNOTSUPP;