From 25b08c7fb0e410bdf7c42ea1faff816eb0451bbc Mon Sep 17 00:00:00 2001 From: James Hogan Date: Fri, 16 Sep 2016 00:06:43 +0100 Subject: [PATCH] KVM: MIPS: Invalidate TLB by regenerating ASIDs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Invalidate host TLB mappings when the guest ASID is changed by regenerating ASIDs, rather than flushing the entire host TLB except entries in the guest KSeg0 range. For the guest kernel mode ASID we regenerate on the spot when the guest ASID is changed, as that will always take place while the guest is in kernel mode. However when the guest invalidates TLB entries the ASID will often by changed temporarily as part of writing EntryHi without the guest returning to user mode in between. We therefore regenerate the user mode ASID lazily before entering the guest in user mode, if and only if the guest ASID has actually changed since the last guest user mode entry. 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 | 3 +++ arch/mips/kvm/emulate.c | 18 +++++++++++++----- arch/mips/kvm/mips.c | 30 ++++++++++++++++++++++++++++++ arch/mips/kvm/mmu.c | 4 ++++ 4 files changed, 50 insertions(+), 5 deletions(-) diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h index 4d7e0e466b5a..a5685c1adba2 100644 --- a/arch/mips/include/asm/kvm_host.h +++ b/arch/mips/include/asm/kvm_host.h @@ -328,6 +328,9 @@ struct kvm_vcpu_arch { u32 guest_kernel_asid[NR_CPUS]; struct mm_struct guest_kernel_mm, guest_user_mm; + /* Guest ASID of last user mode execution */ + unsigned int last_user_gasid; + int last_sched_cpu; /* WAIT executed */ diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c index 43853ec6e160..8dc9e64346e6 100644 --- a/arch/mips/kvm/emulate.c +++ b/arch/mips/kvm/emulate.c @@ -1170,15 +1170,23 @@ enum emulation_result kvm_mips_emulate_CP0(union mips_instruction inst, & KVM_ENTRYHI_ASID, nasid); + /* + * Regenerate/invalidate kernel MMU + * context. + * The user MMU context will be + * regenerated lazily on re-entry to + * guest user if the guest ASID actually + * changes. + */ preempt_disable(); - /* Blow away the shadow host TLBs */ - kvm_mips_flush_host_tlb(1); cpu = smp_processor_id(); + 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]; for_each_possible_cpu(i) - if (i != cpu) { - vcpu->arch.guest_user_asid[i] = 0; + if (i != cpu) vcpu->arch.guest_kernel_asid[i] = 0; - } preempt_enable(); } kvm_write_c0_guest_entryhi(cop0, diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c index a6ea084b4d9d..ad1b15ba5907 100644 --- a/arch/mips/kvm/mips.c +++ b/arch/mips/kvm/mips.c @@ -411,6 +411,31 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, return -ENOIOCTLCMD; } +/* Must be called with preemption disabled, just before entering guest */ +static void kvm_mips_check_asids(struct kvm_vcpu *vcpu) +{ + struct mips_coproc *cop0 = vcpu->arch.cop0; + int cpu = smp_processor_id(); + unsigned int gasid; + + /* + * Lazy host ASID regeneration for guest user mode. + * If the guest ASID has changed since the last guest usermode + * execution, regenerate the host ASID so as to invalidate stale TLB + * entries. + */ + if (!KVM_GUEST_KERNEL_MODE(vcpu)) { + gasid = kvm_read_c0_guest_entryhi(cop0) & KVM_ENTRYHI_ASID; + if (gasid != vcpu->arch.last_user_gasid) { + 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]; + vcpu->arch.last_user_gasid = gasid; + } + } +} + int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) { int r = 0; @@ -438,6 +463,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) htw_stop(); trace_kvm_enter(vcpu); + + kvm_mips_check_asids(vcpu); + r = vcpu->arch.vcpu_run(run, vcpu); trace_kvm_out(vcpu); @@ -1551,6 +1579,8 @@ skip_emul: if (ret == RESUME_GUEST) { trace_kvm_reenter(vcpu); + kvm_mips_check_asids(vcpu); + /* * If FPU / MSA are enabled (i.e. the guest's FPU / MSA context * is live), restore FCR31 / MSACSR. diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c index c1f8758f5323..8e1f2bffcf0f 100644 --- a/arch/mips/kvm/mmu.c +++ b/arch/mips/kvm/mmu.c @@ -260,9 +260,13 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) if ((vcpu->arch.guest_user_asid[cpu] ^ asid_cache(cpu)) & asid_version_mask(cpu)) { + u32 gasid = kvm_read_c0_guest_entryhi(vcpu->arch.cop0) & + KVM_ENTRYHI_ASID; + 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]; + vcpu->arch.last_user_gasid = gasid; newasid++; kvm_debug("[%d]: cpu_context: %#lx\n", cpu,