Commit a7ebb2e4 authored by James Hogan's avatar James Hogan
Browse files

KVM: MIPS/T&E: active_mm = init_mm in guest context 



Set init_mm as the active_mm and update mm_cpumask(current->mm) to
reflect that it isn't active when in guest context. This prevents cache
management code from attempting cache flushes on host virtual addresses
while in guest context, for example due to a cache management IPIs or
later when writing of dynamically translated code hits copy on write.

We do this using helpers in static kernel code to avoid having to export
init_mm to modules.

Signed-off-by: default avatarJames 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
parent 91cdee57

arch/mips/include/asm/kvm_host.h

+4 −0
Original line number Diff line number Diff line
@@ -607,6 +607,10 @@ extern int kvm_mips_host_tlb_inv(struct kvm_vcpu *vcpu, unsigned long entryhi); 
extern int kvm_mips_guest_tlb_lookup(struct kvm_vcpu *vcpu,

				     unsigned long entryhi);

extern int kvm_mips_host_tlb_lookup(struct kvm_vcpu *vcpu, unsigned long vaddr);



void kvm_mips_suspend_mm(int cpu);

void kvm_mips_resume_mm(int cpu);



extern unsigned long kvm_mips_translate_guest_kseg0_to_hpa(struct kvm_vcpu *vcpu,

						   unsigned long gva);

extern void kvm_get_new_mmu_context(struct mm_struct *mm, unsigned long cpu,

arch/mips/kvm/tlb.c

+35 −0
Original line number Diff line number Diff line
@@ -382,3 +382,38 @@ void kvm_local_flush_tlb_all(void) 
	local_irq_restore(flags);

}

EXPORT_SYMBOL_GPL(kvm_local_flush_tlb_all);



/**

 * kvm_mips_suspend_mm() - Suspend the active mm.

 * @cpu		The CPU we're running on.

 *

 * Suspend the active_mm, ready for a switch to a KVM guest virtual address

 * space. This is left active for the duration of guest context, including time

 * with interrupts enabled, so we need to be careful not to confuse e.g. cache

 * management IPIs.

 *

 * kvm_mips_resume_mm() should be called before context switching to a different

 * process so we don't need to worry about reference counting.

 *

 * This needs to be in static kernel code to avoid exporting init_mm.

 */

void kvm_mips_suspend_mm(int cpu)

{

	cpumask_clear_cpu(cpu, mm_cpumask(current->active_mm));

	current->active_mm = &init_mm;

}

EXPORT_SYMBOL_GPL(kvm_mips_suspend_mm);



/**

 * kvm_mips_resume_mm() - Resume the current process mm.

 * @cpu		The CPU we're running on.

 *

 * Resume the mm of the current process, after a switch back from a KVM guest

 * virtual address space (see kvm_mips_suspend_mm()).

 */

void kvm_mips_resume_mm(int cpu)

{

	cpumask_set_cpu(cpu, mm_cpumask(current->mm));

	current->active_mm = current->mm;

}

EXPORT_SYMBOL_GPL(kvm_mips_resume_mm);

arch/mips/kvm/trap_emul.c

+11 −1
Original line number Diff line number Diff line
@@ -670,6 +670,7 @@ static int kvm_trap_emul_vcpu_load(struct kvm_vcpu *vcpu, int cpu) 
			write_c0_entryhi(cpu_asid(cpu, kern_mm));

		else

			write_c0_entryhi(cpu_asid(cpu, user_mm));

		kvm_mips_suspend_mm(cpu);

		ehb();

	}
@@ -689,6 +690,7 @@ static int kvm_trap_emul_vcpu_put(struct kvm_vcpu *vcpu, int cpu) 
			get_new_mmu_context(current->mm, cpu);

		}

		write_c0_entryhi(cpu_asid(cpu, current->mm));

		kvm_mips_resume_mm(cpu);

		ehb();

	}
@@ -723,7 +725,7 @@ static void kvm_trap_emul_vcpu_reenter(struct kvm_run *run, 


static int kvm_trap_emul_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu)

{

	int cpu;

	int cpu = smp_processor_id();

	int r;



	/* Check if we have any exceptions/interrupts pending */
@@ -735,6 +737,13 @@ static int kvm_trap_emul_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu) 
	/* Disable hardware page table walking while in guest */

	htw_stop();



	/*

	 * While in guest context we're in the guest's address space, not the

	 * host process address space, so we need to be careful not to confuse

	 * e.g. cache management IPIs.

	 */

	kvm_mips_suspend_mm(cpu);



	r = vcpu->arch.vcpu_run(run, vcpu);



	/* We may have migrated while handling guest exits */
@@ -745,6 +754,7 @@ static int kvm_trap_emul_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu) 
	     asid_version_mask(cpu)))

		get_new_mmu_context(current->mm, cpu);

	write_c0_entryhi(cpu_asid(cpu, current->mm));

	kvm_mips_resume_mm(cpu);



	htw_start();

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