summaryrefslogtreecommitdiffstats
path: root/arch/mips
diff options
context:
space:
mode:
authorJames Hogan <james.hogan@imgtec.com>2016-10-25 16:08:19 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2016-10-26 13:43:41 +0200
commit9078210ef4016539c909fb67164d3f1c27323d8b (patch)
tree810f0275af6c948768d0581668f64c715f903641 /arch/mips
parent07d9a380680d1c0eb51ef87ff2eab5c994949e69 (diff)
downloadlinux-9078210ef4016539c909fb67164d3f1c27323d8b.tar.bz2
KVM: MIPS: Fix lazy user ASID regenerate for SMP
kvm_mips_check_asids() runs before entering the guest and performs lazy regeneration of host ASID for guest usermode, using last_user_gasid to track the last guest ASID in the VCPU that was used by guest usermode on any host CPU. last_user_gasid is reset after performing the lazy ASID regeneration on the current CPU, and by kvm_arch_vcpu_load() if the host ASID for guest usermode is regenerated due to staleness (to cancel outstanding lazy ASID regenerations). Unfortunately neither case handles SMP hosts correctly: - When the lazy ASID regeneration is performed it should apply to all CPUs (as last_user_gasid does), so reset the ASID on other CPUs to zero to trigger regeneration when the VCPU is next loaded on those CPUs. - When the ASID is found to be stale on the current CPU, we should not cancel lazy ASID regenerations globally, so drop the reset of last_user_gasid altogether here. Both cases would require a guest ASID change and two host CPU migrations (and in the latter case one of the CPUs to start a new ASID cycle) before guest usermode could potentially access stale user pages from a previously running ASID in the same VCPU. Fixes: 25b08c7fb0e4 ("KVM: MIPS: Invalidate TLB by regenerating ASIDs") 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 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/mips')
-rw-r--r--arch/mips/kvm/mips.c5
-rw-r--r--arch/mips/kvm/mmu.c4
2 files changed, 4 insertions, 5 deletions
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 622037d851a3..06a60b19acfb 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -426,7 +426,7 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
static void kvm_mips_check_asids(struct kvm_vcpu *vcpu)
{
struct mips_coproc *cop0 = vcpu->arch.cop0;
- int cpu = smp_processor_id();
+ int i, cpu = smp_processor_id();
unsigned int gasid;
/*
@@ -442,6 +442,9 @@ static void kvm_mips_check_asids(struct kvm_vcpu *vcpu)
vcpu);
vcpu->arch.guest_user_asid[cpu] =
vcpu->arch.guest_user_mm.context.asid[cpu];
+ for_each_possible_cpu(i)
+ if (i != cpu)
+ vcpu->arch.guest_user_asid[cpu] = 0;
vcpu->arch.last_user_gasid = gasid;
}
}
diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
index 03883ba806e2..3b677c851be0 100644
--- a/arch/mips/kvm/mmu.c
+++ b/arch/mips/kvm/mmu.c
@@ -260,13 +260,9 @@ 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,