[XEN PATCH v2] x86/intel: optional build of PSR support

[Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>]

Platform Shared Resource feature is available for certain Intel's CPUs only,
hence can be put under CONFIG_INTEL build option.

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

Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
---
v1 patch here:
https://lore.kernel.org/xen-devel/20240606083908.2510396-1-Sergiy_Kibrik@xxxxxxxx/

changes in v2:
 - split outer switch cases for {XEN_SYSCTL,XEN_DOMCTL}_psr_cmt_op and
   {XEN_SYSCTL,XEN_DOMCTL}_psr_alloc so that return codes in default switch
   cases are not mangled (as Jan suggested)
---
 xen/arch/x86/Makefile          |  2 +-
 xen/arch/x86/domctl.c          |  8 ++++++++
 xen/arch/x86/include/asm/psr.h |  9 +++++++++
 xen/arch/x86/sysctl.c          | 12 +++++++++++-
 4 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index d902fb7acc..02218d32c5 100644
--- a/xen/arch/x86/Makefile
+++ b/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_INTEL) += psr.o
 obj-y += setup.o
 obj-y += shutdown.o
 obj-y += smp.o
diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index 68b5b46d1a..bccd3852a7 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1162,6 +1162,7 @@ long arch_do_domctl(
     }
 
     case XEN_DOMCTL_psr_cmt_op:
+#ifdef CONFIG_INTEL
         if ( !psr_cmt_enabled() )
         {
             ret = -ENODEV;
@@ -1190,11 +1191,16 @@ long arch_do_domctl(
             ret = -ENOSYS;
             break;
         }
+
+#else /* CONFIG_INTEL */
+        ret = -ENOSYS;
+#endif
         break;
 
     case XEN_DOMCTL_psr_alloc:
         switch ( domctl->u.psr_alloc.cmd )
         {
+#ifdef CONFIG_INTEL
         case XEN_DOMCTL_PSR_SET_L3_CBM:
             ret = psr_set_val(d, domctl->u.psr_alloc.target,
                               domctl->u.psr_alloc.data,
@@ -1257,6 +1263,8 @@ long arch_do_domctl(
 
 #undef domctl_psr_get_val
 
+#endif /* CONFIG_INTEL */
+
         default:
             ret = -EOPNOTSUPP;
             break;
diff --git a/xen/arch/x86/include/asm/psr.h b/xen/arch/x86/include/asm/psr.h
index 51df78794c..8a8c2b13d0 100644
--- a/xen/arch/x86/include/asm/psr.h
+++ b/xen/arch/x86/include/asm/psr.h
@@ -72,6 +72,8 @@ static inline bool psr_cmt_enabled(void)
     return !!psr_cmt;
 }
 
+#ifdef CONFIG_INTEL
+
 int psr_alloc_rmid(struct domain *d);
 void psr_free_rmid(struct domain *d);
 void psr_ctxt_switch_to(struct domain *d);
@@ -86,6 +88,13 @@ int psr_set_val(struct domain *d, unsigned int socket,
 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 /* CONFIG_INTEL */
+
 #endif /* __ASM_PSR_H__ */
 
 /*
diff --git a/xen/arch/x86/sysctl.c b/xen/arch/x86/sysctl.c
index 1d40d82c5a..b39b7f68de 100644
--- a/xen/arch/x86/sysctl.c
+++ b/xen/arch/x86/sysctl.c
@@ -32,6 +32,7 @@
 #include <asm/psr.h>
 #include <asm/cpu-policy.h>
 
+#ifdef CONFIG_INTEL
 struct l3_cache_info {
     int ret;
     unsigned long size;
@@ -46,6 +47,7 @@ static void cf_check l3_cache_get(void *arg)
     if ( !l3_info->ret )
         l3_info->size = info.size / 1024; /* in KB unit */
 }
+#endif
 
 static long cf_check smt_up_down_helper(void *data)
 {
@@ -170,6 +172,7 @@ long arch_do_sysctl(
     break;
 
     case XEN_SYSCTL_psr_cmt_op:
+#ifdef CONFIG_INTEL
         if ( !psr_cmt_enabled() )
             return -ENODEV;
 
@@ -218,6 +221,11 @@ long arch_do_sysctl(
             break;
         }
 
+#else /* CONFIG_INTEL*/
+        sysctl->u.psr_cmt_op.u.data = 0;
+        ret = -ENOSYS;
+#endif
+
         if ( __copy_to_guest(u_sysctl, sysctl, 1) )
             ret = -EFAULT;
 
@@ -225,10 +233,11 @@ 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_INTEL
         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 +288,7 @@ long arch_do_sysctl(
             if ( __copy_field_to_guest(u_sysctl, sysctl, u.psr_alloc) )
                 ret = -EFAULT;
             break;
+#endif /* CONFIG_INTEL */
 
         default:
             ret = -EOPNOTSUPP;
-- 
2.25.1