KVM: MIPS/MMU: Move preempt/ASID handling to implementation

The MIPS KVM host and guest GVA ASIDs may need regenerating when
scheduling a process in guest context, which is done from the
kvm_arch_vcpu_load() / kvm_arch_vcpu_put() functions in mmu.c.

However this is a fairly implementation specific detail. VZ for example
may use GuestIDs instead of normal ASIDs to distinguish mappings
belonging to different guests, and even on VZ without GuestID the root
TLB will be used differently to trap & emulate.

Trap & emulate GVA ASIDs only relate to the user part of the full
address space, so can be left active during guest exit handling (guest
context) to allow guest instructions to be easily read and translated.

VZ root ASIDs however are for GPA mappings so can't be left active
during normal kernel code. They also aren't useful for accessing guest
virtual memory, and we should have CP0_BadInstr[P] registers available
to provide encodings of trapping guest instructions anyway.

Therefore move the ASID preemption handling into the implementation
callback.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org

1 files changed, 0 insertions, 51 deletions

diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
index ed46528611f4..df013538113f 100644
--- a/arch/mips/kvm/mmu.c
+++ b/arch/mips/kvm/mmu.c
@@ -235,39 +235,12 @@ static void kvm_mips_migrate_count(struct kvm_vcpu *vcpu)
 /* Restore ASID once we are scheduled back after preemption */
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
-	unsigned long asid_mask = cpu_asid_mask(&cpu_data[cpu]);
 	unsigned long flags;
 
 	kvm_debug("%s: vcpu %p, cpu: %d\n", __func__, vcpu, cpu);
 
-	/* Allocate new kernel and user ASIDs if needed */
-
 	local_irq_save(flags);
 
-	if ((vcpu->arch.guest_kernel_asid[cpu] ^ asid_cache(cpu)) &
-						asid_version_mask(cpu)) {
-		kvm_get_new_mmu_context(&vcpu->arch.guest_kernel_mm, cpu, vcpu);
-		vcpu->arch.guest_kernel_asid[cpu] =
-		    vcpu->arch.guest_kernel_mm.context.asid[cpu];
-
-		kvm_debug("[%d]: cpu_context: %#lx\n", cpu,
-			  cpu_context(cpu, current->mm));
-		kvm_debug("[%d]: Allocated new ASID for Guest Kernel: %#x\n",
-			  cpu, vcpu->arch.guest_kernel_asid[cpu]);
-	}
-
-	if ((vcpu->arch.guest_user_asid[cpu] ^ asid_cache(cpu)) &
-						asid_version_mask(cpu)) {
-		kvm_get_new_mmu_context(&vcpu->arch.guest_user_mm, cpu, vcpu);
-		vcpu->arch.guest_user_asid[cpu] =
-		    vcpu->arch.guest_user_mm.context.asid[cpu];
-
-		kvm_debug("[%d]: cpu_context: %#lx\n", cpu,
-			  cpu_context(cpu, current->mm));
-		kvm_debug("[%d]: Allocated new ASID for Guest User: %#x\n", cpu,
-			  vcpu->arch.guest_user_asid[cpu]);
-	}
-
 	if (vcpu->arch.last_sched_cpu != cpu) {
 		kvm_debug("[%d->%d]KVM VCPU[%d] switch\n",
 			  vcpu->arch.last_sched_cpu, cpu, vcpu->vcpu_id);
@@ -279,25 +252,10 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 		kvm_mips_migrate_count(vcpu);
 	}
 
-	/*
-	 * If we preempted while the guest was executing, then reload the ASID
-	 * based on the mode of the Guest (Kernel/User)
-	 */
-	if (current->flags & PF_VCPU) {
-		if (KVM_GUEST_KERNEL_MODE(vcpu))
-			write_c0_entryhi(vcpu->arch.guest_kernel_asid[cpu] &
-					 asid_mask);
-		else
-			write_c0_entryhi(vcpu->arch.guest_user_asid[cpu] &
-					 asid_mask);
-		ehb();
-	}
-
 	/* restore guest state to registers */
 	kvm_mips_callbacks->vcpu_load(vcpu, cpu);
 
 	local_irq_restore(flags);
-
 }
 
 /* ASID can change if another task is scheduled during preemption */
@@ -314,15 +272,6 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 	/* save guest state in registers */
 	kvm_mips_callbacks->vcpu_put(vcpu, cpu);
 
-	if (((cpu_context(cpu, current->mm) ^ asid_cache(cpu)) &
-	     asid_version_mask(cpu))) {
-		kvm_debug("%s: Dropping MMU Context:  %#lx\n", __func__,
-			  cpu_context(cpu, current->mm));
-		drop_mmu_context(current->mm, cpu);
-	}
-	write_c0_entryhi(cpu_asid(cpu, current->mm));
-	ehb();
-
 	local_irq_restore(flags);
 }