Re: [PATCH 39/59] KVM: arm64: nv: Move last_vcpu_ran to be per s2 mmu

Julien Thierry
2019-07-01T09:10:44Z

On 21/06/2019 10:38, Marc Zyngier wrote:
> last_vcpu_ran has to be per s2 mmu now that we can have multiple S2
> per VM. Let's take this opportunity to perform some cleanup.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
> arch/arm/include/asm/kvm_host.h | 6 +++---
> arch/arm/include/asm/kvm_mmu.h | 2 +-
> arch/arm64/include/asm/kvm_host.h | 6 +++---
> arch/arm64/include/asm/kvm_mmu.h | 2 +-
> arch/arm64/kvm/nested.c | 13 ++++++-------
> virt/kvm/arm/arm.c | 22 ++++------------------
> virt/kvm/arm/mmu.c | 26 ++++++++++++++++++++------
> 7 files changed, 38 insertions(+), 39 deletions(-)
>
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index b821eb2383ad..cc761610e41e 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -63,15 +63,15 @@ struct kvm_s2_mmu {
> pgd_t *pgd;
> phys_addr_t pgd_phys;
>
> + /* The last vcpu id that ran on each physical CPU */
> + int __percpu *last_vcpu_ran;
> +
> struct kvm *kvm;
> };
>
> struct kvm_arch {
> struct kvm_s2_mmu mmu;
>
> - /* The last vcpu id that ran on each physical CPU */
> - int __percpu *last_vcpu_ran;
> -
> /* Stage-2 page table */
> pgd_t *pgd;
> phys_addr_t pgd_phys;
> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> index afabf1fd1d17..7a6e9008ed45 100644
> --- a/arch/arm/include/asm/kvm_mmu.h
> +++ b/arch/arm/include/asm/kvm_mmu.h
> @@ -52,7 +52,7 @@ int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size,
> void free_hyp_pgds(void);
>
> void stage2_unmap_vm(struct kvm *kvm);
> -int kvm_alloc_stage2_pgd(struct kvm_s2_mmu *mmu);
> +int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu);
> void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu);
> int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> phys_addr_t pa, unsigned long size, bool writable);
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index cc238de170d2..b71a7a237f95 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -104,6 +104,9 @@ struct kvm_s2_mmu {
> * >0: Somebody is actively using this.
> */
> atomic_t refcnt;
> +
> + /* The last vcpu id that ran on each physical CPU */
> + int __percpu *last_vcpu_ran;
> };
>
> static inline bool kvm_s2_mmu_valid(struct kvm_s2_mmu *mmu)
> @@ -124,9 +127,6 @@ struct kvm_arch {
> /* VTCR_EL2 value for this VM */
> u64 vtcr;
>
> - /* The last vcpu id that ran on each physical CPU */
> - int __percpu *last_vcpu_ran;
> -
> /* The maximum number of vCPUs depends on the used GIC model */
> int max_vcpus;
>
> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> index f4c5ac5eb95f..53103607065a 100644
> --- a/arch/arm64/include/asm/kvm_mmu.h
> +++ b/arch/arm64/include/asm/kvm_mmu.h
> @@ -169,7 +169,7 @@ void free_hyp_pgds(void);
>
> void kvm_unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 size);
> void stage2_unmap_vm(struct kvm *kvm);
> -int kvm_alloc_stage2_pgd(struct kvm_s2_mmu *mmu);
> +int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu);
> void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu);
> int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> phys_addr_t pa, unsigned long size, bool writable);
> diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
> index 8880033fb6e0..09afafbdc8fe 100644
> --- a/arch/arm64/kvm/nested.c
> +++ b/arch/arm64/kvm/nested.c
> @@ -52,18 +52,17 @@ int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu)
> GFP_KERNEL | __GFP_ZERO);
>
> if (tmp) {
> - if (tmp != kvm->arch.nested_mmus)
> + if (tmp != kvm->arch.nested_mmus) {
> kfree(kvm->arch.nested_mmus);
> + kvm->arch.nested_mmus = NULL;
> + kvm->arch.nested_mmus_size = 0;
> + }
>
> - tmp[num_mmus - 1].kvm = kvm;
> - atomic_set(&tmp[num_mmus - 1].refcnt, 0);
> - ret = kvm_alloc_stage2_pgd(&tmp[num_mmus - 1]);
> + ret = kvm_init_stage2_mmu(kvm, &tmp[num_mmus - 1]);
> if (ret)
> goto out;
>
> - tmp[num_mmus - 2].kvm = kvm;
> - atomic_set(&tmp[num_mmus - 2].refcnt, 0);
> - ret = kvm_alloc_stage2_pgd(&tmp[num_mmus - 2]);
> + ret = kvm_init_stage2_mmu(kvm, &tmp[num_mmus - 2]);
> if (ret) {
> kvm_free_stage2_pgd(&tmp[num_mmus - 1]);
> goto out;
> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index bcca27d5c481..e8b584b79847 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -99,29 +99,21 @@ void kvm_arch_check_processor_compat(void *rtn)
> *(int *)rtn = 0;
> }
>
> -
> /**
> * kvm_arch_init_vm - initializes a VM data structure
> * @kvm: pointer to the KVM struct
> */
> int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> {
> - int ret, cpu;
> + int ret;
>
> ret = kvm_arm_setup_stage2(kvm, type);
> if (ret)
> return ret;
>
> - kvm->arch.last_vcpu_ran = alloc_percpu(typeof(*kvm->arch.last_vcpu_ran));
> - if (!kvm->arch.last_vcpu_ran)
> - return -ENOMEM;
> -
> - for_each_possible_cpu(cpu)
> - *per_cpu_ptr(kvm->arch.last_vcpu_ran, cpu) = -1;
> -
> - ret = kvm_alloc_stage2_pgd(&kvm->arch.mmu);
> + ret = kvm_init_stage2_mmu(kvm, &kvm->arch.mmu);
> if (ret)
> - goto out_fail_alloc;
> + return ret;
>
> /* Mark the initial VMID generation invalid */
> kvm->arch.mmu.vmid.vmid_gen = 0;
> @@ -142,9 +134,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> return ret;
> out_free_stage2_pgd:
> kvm_free_stage2_pgd(&kvm->arch.mmu);
> -out_fail_alloc:
> - free_percpu(kvm->arch.last_vcpu_ran);
> - kvm->arch.last_vcpu_ran = NULL;
> return ret;
> }
>
> @@ -174,9 +163,6 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
>
> kvm_vgic_destroy(kvm);
>
> - free_percpu(kvm->arch.last_vcpu_ran);
> - kvm->arch.last_vcpu_ran = NULL;
> -
> for (i = 0; i < KVM_MAX_VCPUS; ++i) {
> if (kvm->vcpus[i]) {
> kvm_arch_vcpu_free(kvm->vcpus[i]);
> @@ -359,7 +345,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> if (nested_virt_in_use(vcpu))
> kvm_vcpu_load_hw_mmu(vcpu);
>
> - last_ran = this_cpu_ptr(vcpu->kvm->arch.last_vcpu_ran);
> + last_ran = this_cpu_ptr(vcpu->arch.hw_mmu->last_vcpu_ran);
> cpu_data = this_cpu_ptr(&kvm_host_data);
>
> /*
> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
> index 94d400e7af57..6a7cba077bce 100644
> --- a/virt/kvm/arm/mmu.c
> +++ b/virt/kvm/arm/mmu.c
> @@ -903,8 +903,9 @@ int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size,
> }
>
> /**
> - * kvm_alloc_stage2_pgd - allocate level-1 table for stage-2 translation.
> - * @mmu: The stage 2 mmu struct pointer
> + * kvm_init_stage2_mmu - Initialise a S2 MMU strucrure
> + * @kvm: The pointer to the KVM structure
> + * @mmu: The pointer to the s2 MMU structure
> *
> * Allocates only the stage-2 HW PGD level table(s) of size defined by
> * stage2_pgd_size(mmu->kvm).
> @@ -912,10 +913,11 @@ int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size,
> * Note we don't need locking here as this is only called when the VM is
> * created, which can only be done once.
> */
> -int kvm_alloc_stage2_pgd(struct kvm_s2_mmu *mmu)
> +int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu)
> {
> phys_addr_t pgd_phys;
> pgd_t *pgd;
> + int cpu;
>
> if (mmu->pgd != NULL) {
> kvm_err("kvm_arch already initialized?\n");
> @@ -923,18 +925,28 @@ int kvm_alloc_stage2_pgd(struct kvm_s2_mmu *mmu)
> }
>
> /* Allocate the HW PGD, making sure that each page gets its own refcount */
> - pgd = alloc_pages_exact(stage2_pgd_size(mmu->kvm), GFP_KERNEL | __GFP_ZERO);
> + pgd = alloc_pages_exact(stage2_pgd_size(kvm), GFP_KERNEL | __GFP_ZERO);
> if (!pgd)
> return -ENOMEM;
>
> pgd_phys = virt_to_phys(pgd);
> - if (WARN_ON(pgd_phys & ~kvm_vttbr_baddr_mask(mmu->kvm)))
> + if (WARN_ON(pgd_phys & ~kvm_vttbr_baddr_mask(kvm)))
> return -EINVAL;
>
> + mmu->last_vcpu_ran = alloc_percpu(typeof(*mmu->last_vcpu_ran));
> + if (!mmu->last_vcpu_ran) {
> + free_pages_exact(pgd, stage2_pgd_size(kvm));
> + return -ENOMEM;
> + }
> +
> + mmu->kvm = kvm;

If we're initializing this here, we probably want to get rid of the
assignment in kvm_arch_init_vm().

> mmu->pgd = pgd;
> mmu->pgd_phys = pgd_phys;
> mmu->vmid.vmid_gen = 0;
>
> + for_each_possible_cpu(cpu)
> + *per_cpu_ptr(mmu->last_vcpu_ran, cpu) = -1;

Nit: I'd suggest putting that right after the allocation of last_vcpu_ran.

> +
> kvm_init_s2_mmu(mmu);

Hmm, now we have kvm_init_stage2_mmu() and an arch (arm or arm64)
specific kvm_init_s2_mmu()...

If we want to keep the s2 mmu structure different for arm and arm64, I'd
suggest at least renaming kvm_init_s2_mmu() so the distinction with
kvm_init_stage2_mmu() is clearer.

>
> return 0;
> @@ -1021,8 +1033,10 @@ void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
> spin_unlock(&kvm->mmu_lock);
>
> /* Free the HW pgd, one page at a time */
> - if (pgd)
> + if (pgd) {
> free_pages_exact(pgd, stage2_pgd_size(kvm));
> + free_percpu(mmu->last_vcpu_ran);
> + }
> }
>
> static pud_t *stage2_get_pud(struct kvm_s2_mmu *mmu, struct kvm_mmu_memory_cache *cache,
>

Cheers,

--
Julien Thierry