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.
Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: "Radim Krčmář" <rkrcmar@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
---
arch/mips/kvm/trap_emul.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/arch/mips/kvm/trap_emul.c b/arch/mips/kvm/trap_emul.c
index 3e1dbcbcea85..ab3750f6a768 100644
--- a/arch/mips/kvm/trap_emul.c
+++ b/arch/mips/kvm/trap_emul.c
@@ -670,6 +670,8 @@ 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));
+ cpumask_clear_cpu(cpu, mm_cpumask(current->active_mm));
+ current->active_mm = &init_mm;
ehb();
}
@@ -689,6 +691,8 @@ 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));
+ cpumask_set_cpu(cpu, mm_cpumask(current->mm));
+ current->active_mm = current->mm;
ehb();
}
@@ -723,7 +727,7 @@ 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 +739,14 @@ 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.
+ */
+ cpumask_clear_cpu(cpu, mm_cpumask(current->active_mm));
+ current->active_mm = &init_mm;
+
r = vcpu->arch.vcpu_run(run, vcpu);
/* We may have migrated while handling guest exits */
@@ -745,6 +757,8 @@ 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));
+ cpumask_set_cpu(cpu, mm_cpumask(current->mm));
+ current->active_mm = current->mm;
htw_start();
--
git-series 0.8.10
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