[XEN PATCH v3] 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>
---
v2 patch here:
https://lore.kernel.org/xen-devel/20240801084453.1163506-1-Sergiy_Kibrik@xxxxxxxx/

changes in v3:
 - drop stubs for psr_domain_{init,free} & psr_ctxt_switch_to() and guard these
   routines at call sites
 - add stub for psr_cmt_enabled()
 - drop some of #ifdef-s from arch_do_{domctl,sysctl}
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/domain.c          | 12 ++++++++----
 xen/arch/x86/domctl.c          |  3 +++
 xen/arch/x86/include/asm/psr.h |  7 +++++++
 xen/arch/x86/sysctl.c          |  4 +++-
 5 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 286c003ec3..4d1ba2a3a1 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/domain.c b/xen/arch/x86/domain.c
index 89aad7e897..ebe648ef80 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -861,7 +861,8 @@ int arch_domain_create(struct domain *d,
     if ( (rc = iommu_domain_init(d, config->iommu_opts)) != 0 )
         goto fail;
 
-    psr_domain_init(d);
+    if ( IS_ENABLED(CONFIG_INTEL) )
+        psr_domain_init(d);
 
     if ( is_hvm_domain(d) )
     {
@@ -902,7 +903,8 @@ int arch_domain_create(struct domain *d,
 
  fail:
     d->is_dying = DOMDYING_dead;
-    psr_domain_free(d);
+    if ( IS_ENABLED(CONFIG_INTEL) )
+        psr_domain_free(d);
     iommu_domain_destroy(d);
     cleanup_domain_irq_mapping(d);
     free_xenheap_page(d->shared_info);
@@ -940,7 +942,8 @@ void arch_domain_destroy(struct domain *d)
     free_xenheap_page(d->shared_info);
     cleanup_domain_irq_mapping(d);
 
-    psr_domain_free(d);
+    if ( IS_ENABLED(CONFIG_INTEL) )
+        psr_domain_free(d);
 }
 
 void arch_domain_shutdown(struct domain *d)
@@ -2024,7 +2027,8 @@ static void __context_switch(void)
         nd->arch.ctxt_switch->to(n);
     }
 
-    psr_ctxt_switch_to(nd);
+    if ( IS_ENABLED(CONFIG_INTEL) )
+        psr_ctxt_switch_to(nd);
 
     if ( need_full_gdt(nd) )
         update_xen_slot_in_full_gdt(n, cpu);
diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index 68b5b46d1a..bd8baaae20 100644
--- a/xen/arch/x86/domctl.c
+++ b/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_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 +1258,8 @@ 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..d42c7f1580 100644
--- a/xen/arch/x86/include/asm/psr.h
+++ b/xen/arch/x86/include/asm/psr.h
@@ -67,10 +67,17 @@ enum psr_type {
 
 extern struct psr_cmt *psr_cmt;
 
+#ifdef CONFIG_INTEL
 static inline bool psr_cmt_enabled(void)
 {
     return !!psr_cmt;
 }
+#else
+static inline bool psr_cmt_enabled(void)
+{
+    return false;
+}
+#endif /* CONFIG_INTEL */
 
 int psr_alloc_rmid(struct domain *d);
 void psr_free_rmid(struct domain *d);
diff --git a/xen/arch/x86/sysctl.c b/xen/arch/x86/sysctl.c
index 1d40d82c5a..8b0d1f1e32 100644
--- a/xen/arch/x86/sysctl.c
+++ b/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_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 +280,7 @@ 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