[Xen-devel] [PATCH 3/6] X86: improve psr scheduling code

[Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>]

Switching RMID from previous vcpu to next vcpu only needs to write
MSR_IA32_PSR_ASSOC once. Write it with the value of next vcpu is enough,
no need to write '0' first. Idle domain has RMID set to 0 so just switch
it as it does.

Introduce a generic routine for this so that other psr features can fit.

Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/domain.c     | 7 ++-----
 xen/arch/x86/psr.c        | 6 ++++++
 xen/include/asm-x86/psr.h | 3 ++-
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index e3b0724..c9be83b 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1447,8 +1447,6 @@ static void __context_switch(void)
     {
         memcpy(&p->arch.user_regs, stack_regs, CTXT_SWITCH_STACK_BYTES);
         vcpu_save_fpu(p);
-        if ( psr_cmt_enabled() )
-            psr_assoc_rmid(0);
         p->arch.ctxt_switch_from(p);
     }
 
@@ -1473,11 +1471,10 @@ static void __context_switch(void)
         }
         vcpu_restore_fpu_eager(n);
         n->arch.ctxt_switch_to(n);
-
-        if ( psr_cmt_enabled() && n->domain->arch.psr_rmid > 0 )
-            psr_assoc_rmid(n->domain->arch.psr_rmid);
     }
 
+    psr_ctxt_switch_to(n->domain);
+
     gdt = !is_pv_32on64_vcpu(n) ? per_cpu(gdt_table, cpu) :
                                   per_cpu(compat_gdt_table, cpu);
     if ( need_full_gdt(n) )
diff --git a/xen/arch/x86/psr.c b/xen/arch/x86/psr.c
index 4325eaf..8c96c1b 100644
--- a/xen/arch/x86/psr.c
+++ b/xen/arch/x86/psr.c
@@ -407,6 +407,12 @@ void psr_domain_free(struct domain *d)
     psr_free_cos(d);
 }
 
+void psr_ctxt_switch_to(struct domain *d)
+{
+    if ( psr_cmt_enabled() )
+        psr_assoc_rmid(d->arch.psr_rmid);
+}
+
 static void do_cat_cpu_init(void* data)
 {
     unsigned int eax, ebx, ecx, edx;
diff --git a/xen/include/asm-x86/psr.h b/xen/include/asm-x86/psr.h
index 999a4c6..212ba30 100644
--- a/xen/include/asm-x86/psr.h
+++ b/xen/include/asm-x86/psr.h
@@ -46,7 +46,6 @@ static inline bool_t psr_cmt_enabled(void)
 
 int psr_alloc_rmid(struct domain *d);
 void psr_free_rmid(struct domain *d);
-void psr_assoc_rmid(unsigned int rmid);
 
 int psr_get_cat_l3_info(unsigned int socket, uint32_t *cbm_len,
                         uint32_t *cos_max);
@@ -56,6 +55,8 @@ int psr_set_l3_cbm(struct domain *d, unsigned int socket, 
uint64_t cbm);
 int psr_domain_init(struct domain *d);
 void psr_domain_free(struct domain *d);
 
+void psr_ctxt_switch_to(struct domain *d);
+
 #endif /* __ASM_PSR_H__ */
 
 /*
-- 
1.9.1


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