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| author | James Hogan <james.hogan@imgtec.com> | 2016-10-25 16:08:19 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-10-26 13:43:41 +0200 |
| commit | 9078210ef4016539c909fb67164d3f1c27323d8b (patch) | |
| tree | 810f0275af6c948768d0581668f64c715f903641 | |
| parent | 07d9a380680d1c0eb51ef87ff2eab5c994949e69 (diff) | |
| download | linux-stable-9078210ef4016539c909fb67164d3f1c27323d8b.tar.gz linux-stable-9078210ef4016539c909fb67164d3f1c27323d8b.tar.bz2 linux-stable-9078210ef4016539c909fb67164d3f1c27323d8b.zip | |
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>
| -rw-r--r-- | arch/mips/kvm/mips.c | 5 | ||||
| -rw-r--r-- | arch/mips/kvm/mmu.c | 4 |
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, |