MIPS: mm: Unify ASID version checks

Introduce a new check_mmu_context() function to check an mm's ASID
version & get a new one if it's outdated, and a
check_switch_mmu_context() function which additionally sets up the new
ASID & page directory. Simplify switch_mm() & various
get_new_mmu_context() callsites in MIPS KVM by making use of the new
functions, which will help reduce the amount of code that requires
modification to gain MMID support.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org

arch/mips/include/asm/mmu_context.h

@@ -98,6 +98,8 @@ static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 }
 
 extern void get_new_mmu_context(struct mm_struct *mm);
+extern void check_mmu_context(struct mm_struct *mm);
+extern void check_switch_mmu_context(struct mm_struct *mm);
 
 /*
  * Initialize the context related info for a new mm_struct
@@ -126,11 +128,7 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 	local_irq_save(flags);
 
 	htw_stop();
-	/* Check if our ASID is of an older version and thus invalid */
-	if ((cpu_context(cpu, next) ^ asid_cache(cpu)) & asid_version_mask(cpu))
-		get_new_mmu_context(next);
-	write_c0_entryhi(cpu_asid(cpu, next));
-	TLBMISS_HANDLER_SETUP_PGD(next->pgd);
+	check_switch_mmu_context(next);
 
 	/*
 	 * Mark current->active_mm as not "active" anymore.

arch/mips/kvm/trap_emul.c

@@ -1056,11 +1056,7 @@ static int kvm_trap_emul_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	 */
 	if (current->flags & PF_VCPU) {
 		mm = KVM_GUEST_KERNEL_MODE(vcpu) ? kern_mm : user_mm;
-		if ((cpu_context(cpu, mm) ^ asid_cache(cpu)) &
-		    asid_version_mask(cpu))
-			get_new_mmu_context(mm);
-		write_c0_entryhi(cpu_asid(cpu, mm));
-		TLBMISS_HANDLER_SETUP_PGD(mm->pgd);
+		check_switch_mmu_context(mm);
 		kvm_mips_suspend_mm(cpu);
 		ehb();
 	}
@@ -1074,11 +1070,7 @@ static int kvm_trap_emul_vcpu_put(struct kvm_vcpu *vcpu, int cpu)
 
 	if (current->flags & PF_VCPU) {
 		/* Restore normal Linux process memory map */
-		if (((cpu_context(cpu, current->mm) ^ asid_cache(cpu)) &
-		     asid_version_mask(cpu)))
-			get_new_mmu_context(current->mm);
-		write_c0_entryhi(cpu_asid(cpu, current->mm));
-		TLBMISS_HANDLER_SETUP_PGD(current->mm->pgd);
+		check_switch_mmu_context(current->mm);
 		kvm_mips_resume_mm(cpu);
 		ehb();
 	}
@@ -1228,9 +1220,7 @@ static void kvm_trap_emul_vcpu_reenter(struct kvm_run *run,
 	 * Check if ASID is stale. This may happen due to a TLB flush request or
 	 * a lazy user MM invalidation.
 	 */
-	if ((cpu_context(cpu, mm) ^ asid_cache(cpu)) &
-	    asid_version_mask(cpu))
-		get_new_mmu_context(mm);
+	check_mmu_context(mm);
 }
 
 static int kvm_trap_emul_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu)
@@ -1266,11 +1256,7 @@ static int kvm_trap_emul_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu)
 	cpu = smp_processor_id();
 
 	/* Restore normal Linux process memory map */
-	if (((cpu_context(cpu, current->mm) ^ asid_cache(cpu)) &
-	     asid_version_mask(cpu)))
-		get_new_mmu_context(current->mm);
-	write_c0_entryhi(cpu_asid(cpu, current->mm));
-	TLBMISS_HANDLER_SETUP_PGD(current->mm->pgd);
+	check_switch_mmu_context(current->mm);
 	kvm_mips_resume_mm(cpu);
 
 	htw_start();

arch/mips/kvm/vz.c

@@ -2454,10 +2454,10 @@ static void kvm_vz_vcpu_load_tlb(struct kvm_vcpu *vcpu, int cpu)
 		 * Root ASID dealiases guest GPA mappings in the root TLB.
 		 * Allocate new root ASID if needed.
 		 */
-		if (cpumask_test_and_clear_cpu(cpu, &kvm->arch.asid_flush_mask)
-		    || (cpu_context(cpu, gpa_mm) ^ asid_cache(cpu)) &
-						asid_version_mask(cpu))
+		if (cpumask_test_and_clear_cpu(cpu, &kvm->arch.asid_flush_mask))
 			get_new_mmu_context(gpa_mm);
+		else
+			check_mmu_context(gpa_mm);
 	}
 }
 

arch/mips/mm/context.c

@@ -17,3 +17,21 @@ void get_new_mmu_context(struct mm_struct *mm)
 
 	cpu_context(cpu, mm) = asid_cache(cpu) = asid;
 }
+
+void check_mmu_context(struct mm_struct *mm)
+{
+	unsigned int cpu = smp_processor_id();
+
+	/* Check if our ASID is of an older version and thus invalid */
+	if ((cpu_context(cpu, mm) ^ asid_cache(cpu)) & asid_version_mask(cpu))
+		get_new_mmu_context(mm);
+}
+
+void check_switch_mmu_context(struct mm_struct *mm)
+{
+	unsigned int cpu = smp_processor_id();
+
+	check_mmu_context(mm);
+	write_c0_entryhi(cpu_asid(cpu, mm));
+	TLBMISS_HANDLER_SETUP_PGD(mm->pgd);
+}