From a7ebb2e410f8be2b061557fd85241d75a1094221 Mon Sep 17 00:00:00 2001 From: James Hogan Date: Tue, 15 Nov 2016 00:06:05 +0000 Subject: [PATCH] KVM: MIPS/T&E: active_mm = init_mm in guest context MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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: James Hogan Cc: Paolo Bonzini Cc: "Radim Krčmář" Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org --- arch/mips/include/asm/kvm_host.h | 4 ++++ arch/mips/kvm/tlb.c | 35 ++++++++++++++++++++++++++++++++ arch/mips/kvm/trap_emul.c | 12 ++++++++++- 3 files changed, 50 insertions(+), 1 deletion(-) diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h index 9f319375835a..95320b7964a6 100644 --- a/arch/mips/include/asm/kvm_host.h +++ b/arch/mips/include/asm/kvm_host.h @@ -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, diff --git a/arch/mips/kvm/tlb.c b/arch/mips/kvm/tlb.c index ba490130b5e7..6c1f894b8754 100644 --- a/arch/mips/kvm/tlb.c +++ b/arch/mips/kvm/tlb.c @@ -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); diff --git a/arch/mips/kvm/trap_emul.c b/arch/mips/kvm/trap_emul.c index 3e1dbcbcea85..9cfe4d2a283c 100644 --- a/arch/mips/kvm/trap_emul.c +++ b/arch/mips/kvm/trap_emul.c @@ -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(); -- 2.30.2