| Message ID | 20201210160002.1407373-64-maz@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: ARMv8.3/8.4 Nested Virtualization support | expand |
On Fri, 11 Dec 2020 at 00:04, Marc Zyngier <maz@kernel.org> wrote: > > If running a NV guest on an ARMv8.4-NV capable system, let's > allocate an additional page that will be used by the hypervisor > to fulfill system register accesses. > > Signed-off-by: Marc Zyngier <maz@kernel.org> > --- > arch/arm64/include/asm/kvm_host.h | 3 ++- > arch/arm64/kvm/nested.c | 8 ++++++++ > arch/arm64/kvm/reset.c | 1 + > 3 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 78630bd5124d..dada0678c28e 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -523,7 +523,8 @@ struct kvm_vcpu_arch { > */ > static inline u64 *__ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r) > { > - if (unlikely(r >= __VNCR_START__ && ctxt->vncr_array)) > + if (unlikely(cpus_have_final_cap(ARM64_HAS_ENHANCED_NESTED_VIRT) && > + r >= __VNCR_START__ && ctxt->vncr_array)) > return &ctxt->vncr_array[r - __VNCR_START__]; > > return (u64 *)&ctxt->sys_regs[r]; > diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c > index eef8f9873814..88147ec99755 100644 > --- a/arch/arm64/kvm/nested.c > +++ b/arch/arm64/kvm/nested.c > @@ -47,6 +47,12 @@ int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu) > if (!cpus_have_final_cap(ARM64_HAS_NESTED_VIRT)) > return -EINVAL; > > + if (cpus_have_final_cap(ARM64_HAS_ENHANCED_NESTED_VIRT)) { > + vcpu->arch.ctxt.vncr_array = (u64 *)__get_free_page(GFP_KERNEL | __GFP_ZERO); > + if (!vcpu->arch.ctxt.vncr_array) > + return -ENOMEM; > + } > + If KVM_ARM_VCPU_INIT was called multiple times, the above codes would try to allocate a new page without free-ing the previous one. Besides that, the following kvm_free_stage2_pgd() call would fail in the second call with the error message "kvm_arch already initialized?". I think a possible fix is to add a new flag to indicate whether the NV related meta data have been initialized, and only initialize them for the first call. > mutex_lock(&kvm->lock); > > /* > @@ -64,6 +70,8 @@ int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu) > kvm_init_stage2_mmu(kvm, &tmp[num_mmus - 2])) { > kvm_free_stage2_pgd(&tmp[num_mmus - 1]); > kvm_free_stage2_pgd(&tmp[num_mmus - 2]); > + free_page((unsigned long)vcpu->arch.ctxt.vncr_array); > + vcpu->arch.ctxt.vncr_array = NULL; > } else { > kvm->arch.nested_mmus_size = num_mmus; > ret = 0; > diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c > index 2d2c780e6c69..d281eb39036f 100644 > --- a/arch/arm64/kvm/reset.c > +++ b/arch/arm64/kvm/reset.c > @@ -150,6 +150,7 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu) > void kvm_arm_vcpu_destroy(struct kvm_vcpu *vcpu) > { > kfree(vcpu->arch.sve_state); > + free_page((unsigned long)vcpu->arch.ctxt.vncr_array); > } > > static void kvm_vcpu_reset_sve(struct kvm_vcpu *vcpu) > -- > 2.29.2 > > _______________________________________________ > kvmarm mailing list > kvmarm@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
On Thu, 21 Jan 2021 02:47:45 +0000, Haibo Xu <haibo.xu@linaro.org> wrote: > > On Fri, 11 Dec 2020 at 00:04, Marc Zyngier <maz@kernel.org> wrote: > > > > If running a NV guest on an ARMv8.4-NV capable system, let's > > allocate an additional page that will be used by the hypervisor > > to fulfill system register accesses. > > > > Signed-off-by: Marc Zyngier <maz@kernel.org> > > --- > > arch/arm64/include/asm/kvm_host.h | 3 ++- > > arch/arm64/kvm/nested.c | 8 ++++++++ > > arch/arm64/kvm/reset.c | 1 + > > 3 files changed, 11 insertions(+), 1 deletion(-) > > > > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > > index 78630bd5124d..dada0678c28e 100644 > > --- a/arch/arm64/include/asm/kvm_host.h > > +++ b/arch/arm64/include/asm/kvm_host.h > > @@ -523,7 +523,8 @@ struct kvm_vcpu_arch { > > */ > > static inline u64 *__ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r) > > { > > - if (unlikely(r >= __VNCR_START__ && ctxt->vncr_array)) > > + if (unlikely(cpus_have_final_cap(ARM64_HAS_ENHANCED_NESTED_VIRT) && > > + r >= __VNCR_START__ && ctxt->vncr_array)) > > return &ctxt->vncr_array[r - __VNCR_START__]; > > > > return (u64 *)&ctxt->sys_regs[r]; > > diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c > > index eef8f9873814..88147ec99755 100644 > > --- a/arch/arm64/kvm/nested.c > > +++ b/arch/arm64/kvm/nested.c > > @@ -47,6 +47,12 @@ int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu) > > if (!cpus_have_final_cap(ARM64_HAS_NESTED_VIRT)) > > return -EINVAL; > > > > + if (cpus_have_final_cap(ARM64_HAS_ENHANCED_NESTED_VIRT)) { > > + vcpu->arch.ctxt.vncr_array = (u64 *)__get_free_page(GFP_KERNEL | __GFP_ZERO); > > + if (!vcpu->arch.ctxt.vncr_array) > > + return -ENOMEM; > > + } > > + > > If KVM_ARM_VCPU_INIT was called multiple times, the above codes > would try to allocate a new page without free-ing the previous > one. Besides that, the following kvm_free_stage2_pgd() call would I assume you mean kvm_init_stage2_mmu() here. > fail in the second call with the error message "kvm_arch already > initialized?". I think a possible fix is to add a new flag to > indicate whether the NV related meta data have been initialized, and > only initialize them for the first call. Good catch. But I think we have all the data we need at this stage to avoid this issue: diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index abb0669bdd4c..baff7373863f 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -390,7 +390,20 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu) int cpu, err; struct kvm_pgtable *pgt; + /* + * If we already have our page tables in place, and that the + * MMU context is the canonical one, we have a bug somewhere, + * as this is only supposed to ever happen once per VM. + * + * Otherwise, we're building nested page tables, and that's + * probably because userspace called KVM_ARM_VCPU_INIT more + * than once on the same vcpu. Since that's actually legal, + * don't kick a fuss and leave gracefully. + */ if (mmu->pgt != NULL) { + if (&kvm->arch.mmu != mmu) + return 0; + kvm_err("kvm_arch already initialized?\n"); return -EINVAL; } diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index 88147ec99755..3b21ea57fbce 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -48,7 +48,9 @@ int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu) return -EINVAL; if (cpus_have_final_cap(ARM64_HAS_ENHANCED_NESTED_VIRT)) { - vcpu->arch.ctxt.vncr_array = (u64 *)__get_free_page(GFP_KERNEL | __GFP_ZERO); + if (!vcpu->arch.ctxt.vncr_array) + vcpu->arch.ctxt.vncr_array = (u64 *)__get_free_page(GFP_KERNEL | __GFP_ZERO); + if (!vcpu->arch.ctxt.vncr_array) return -ENOMEM; } Thanks, M.
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 78630bd5124d..dada0678c28e 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -523,7 +523,8 @@ struct kvm_vcpu_arch { */ static inline u64 *__ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r) { - if (unlikely(r >= __VNCR_START__ && ctxt->vncr_array)) + if (unlikely(cpus_have_final_cap(ARM64_HAS_ENHANCED_NESTED_VIRT) && + r >= __VNCR_START__ && ctxt->vncr_array)) return &ctxt->vncr_array[r - __VNCR_START__]; return (u64 *)&ctxt->sys_regs[r]; diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index eef8f9873814..88147ec99755 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -47,6 +47,12 @@ int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu) if (!cpus_have_final_cap(ARM64_HAS_NESTED_VIRT)) return -EINVAL; + if (cpus_have_final_cap(ARM64_HAS_ENHANCED_NESTED_VIRT)) { + vcpu->arch.ctxt.vncr_array = (u64 *)__get_free_page(GFP_KERNEL | __GFP_ZERO); + if (!vcpu->arch.ctxt.vncr_array) + return -ENOMEM; + } + mutex_lock(&kvm->lock); /* @@ -64,6 +70,8 @@ int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu) kvm_init_stage2_mmu(kvm, &tmp[num_mmus - 2])) { kvm_free_stage2_pgd(&tmp[num_mmus - 1]); kvm_free_stage2_pgd(&tmp[num_mmus - 2]); + free_page((unsigned long)vcpu->arch.ctxt.vncr_array); + vcpu->arch.ctxt.vncr_array = NULL; } else { kvm->arch.nested_mmus_size = num_mmus; ret = 0; diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c index 2d2c780e6c69..d281eb39036f 100644 --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -150,6 +150,7 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu) void kvm_arm_vcpu_destroy(struct kvm_vcpu *vcpu) { kfree(vcpu->arch.sve_state); + free_page((unsigned long)vcpu->arch.ctxt.vncr_array); } static void kvm_vcpu_reset_sve(struct kvm_vcpu *vcpu)
If running a NV guest on an ARMv8.4-NV capable system, let's allocate an additional page that will be used by the hypervisor to fulfill system register accesses. Signed-off-by: Marc Zyngier <maz@kernel.org> --- arch/arm64/include/asm/kvm_host.h | 3 ++- arch/arm64/kvm/nested.c | 8 ++++++++ arch/arm64/kvm/reset.c | 1 + 3 files changed, 11 insertions(+), 1 deletion(-)