From patchwork Mon May 10 16:58:47 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 12249001 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33161C43460 for ; Mon, 10 May 2021 17:28:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1359561480 for ; Mon, 10 May 2021 17:28:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232910AbhEJR3z (ORCPT ); Mon, 10 May 2021 13:29:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:54210 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232917AbhEJR3Q (ORCPT ); Mon, 10 May 2021 13:29:16 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0B6A1614A7; Mon, 10 May 2021 17:28:09 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1lg9GV-000Uqg-KM; Mon, 10 May 2021 18:00:19 +0100 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Cc: Andre Przywara , Christoffer Dall , Jintack Lim , Haibo Xu , James Morse , Suzuki K Poulose , Alexandru Elisei , kernel-team@android.com Subject: [PATCH v4 33/66] KVM: arm64: nv: Support multiple nested Stage-2 mmu structures Date: Mon, 10 May 2021 17:58:47 +0100 Message-Id: <20210510165920.1913477-34-maz@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210510165920.1913477-1-maz@kernel.org> References: <20210510165920.1913477-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, andre.przywara@arm.com, christoffer.dall@arm.com, jintack@cs.columbia.edu, haibo.xu@linaro.org, james.morse@arm.com, suzuki.poulose@arm.com, alexandru.elisei@arm.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Add Stage-2 mmu data structures for virtual EL2 and for nested guests. We don't yet populate shadow Stage-2 page tables, but we now have a framework for getting to a shadow Stage-2 pgd. We allocate twice the number of vcpus as Stage-2 mmu structures because that's sufficient for each vcpu running two translation regimes without having to flush the Stage-2 page tables. Co-developed-by: Christoffer Dall Signed-off-by: Christoffer Dall Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/kvm_host.h | 29 +++++ arch/arm64/include/asm/kvm_mmu.h | 9 ++ arch/arm64/include/asm/kvm_nested.h | 7 ++ arch/arm64/kvm/arm.c | 16 ++- arch/arm64/kvm/mmu.c | 31 +++-- arch/arm64/kvm/nested.c | 183 ++++++++++++++++++++++++++++ 6 files changed, 264 insertions(+), 11 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 1d82ad3c63b8..b7d6a829091c 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -95,14 +95,43 @@ struct kvm_s2_mmu { int __percpu *last_vcpu_ran; struct kvm_arch *arch; + + /* + * For a shadow stage-2 MMU, the virtual vttbr programmed by the guest + * hypervisor. Unused for kvm_arch->mmu. Set to 1 when the structure + * contains no valid information. + */ + u64 vttbr; + + /* true when this represents a nested context where virtual HCR_EL2.VM == 1 */ + bool nested_stage2_enabled; + + /* + * 0: Nobody is currently using this, check vttbr for validity + * >0: Somebody is actively using this. + */ + atomic_t refcnt; }; +static inline bool kvm_s2_mmu_valid(struct kvm_s2_mmu *mmu) +{ + return !(mmu->vttbr & 1); +} + struct kvm_arch_memory_slot { }; struct kvm_arch { struct kvm_s2_mmu mmu; + /* + * Stage 2 paging stage for VMs with nested virtual using a virtual + * VMID. + */ + struct kvm_s2_mmu *nested_mmus; + size_t nested_mmus_size; + int nested_mmus_next; + /* VTCR_EL2 value for this VM */ u64 vtcr; diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h index 0be00ec66e0f..579980a8b05f 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -116,6 +116,7 @@ alternative_cb_end #include #include #include +#include void kvm_update_va_mask(struct alt_instr *alt, __le32 *origptr, __le32 *updptr, int nr_inst); @@ -159,6 +160,7 @@ int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size, void **haddr); 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_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu); void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu); @@ -298,5 +300,12 @@ static inline struct kvm *kvm_s2_mmu_to_kvm(struct kvm_s2_mmu *mmu) { return container_of(mmu->arch, struct kvm, arch); } + +static inline u64 get_vmid(u64 vttbr) +{ + return (vttbr & VTTBR_VMID_MASK(kvm_get_vmid_bits())) >> + VTTBR_VMID_SHIFT; +} + #endif /* __ASSEMBLY__ */ #endif /* __ARM64_KVM_MMU_H__ */ diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h index 026ddaad972c..473ecd1d60d0 100644 --- a/arch/arm64/include/asm/kvm_nested.h +++ b/arch/arm64/include/asm/kvm_nested.h @@ -61,6 +61,13 @@ static inline u64 translate_cnthctl_el2_to_cntkctl_el1(u64 cnthctl) (cnthctl & (CNTHCTL_EVNTI | CNTHCTL_EVNTDIR | CNTHCTL_EVNTEN))); } +extern void kvm_init_nested(struct kvm *kvm); +extern int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu); +extern void kvm_init_nested_s2_mmu(struct kvm_s2_mmu *mmu); +extern struct kvm_s2_mmu *lookup_s2_mmu(struct kvm *kvm, u64 vttbr, u64 hcr); +extern void kvm_vcpu_load_hw_mmu(struct kvm_vcpu *vcpu); +extern void kvm_vcpu_put_hw_mmu(struct kvm_vcpu *vcpu); + int handle_wfx_nested(struct kvm_vcpu *vcpu, bool is_wfe); extern bool __forward_traps(struct kvm_vcpu *vcpu, unsigned int reg, u64 control_bit); diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 1cb39c0803a4..8cadfaa2a310 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -35,6 +35,7 @@ #include #include #include +#include #include #include @@ -138,6 +139,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) if (ret) return ret; + kvm_init_nested(kvm); + ret = create_hyp_mappings(kvm, kvm + 1, PAGE_HYP); if (ret) goto out_free_stage2_pgd; @@ -384,6 +387,9 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) struct kvm_s2_mmu *mmu; int *last_ran; + if (nested_virt_in_use(vcpu)) + kvm_vcpu_load_hw_mmu(vcpu); + mmu = vcpu->arch.hw_mmu; last_ran = this_cpu_ptr(mmu->last_vcpu_ran); @@ -432,6 +438,9 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) kvm_vgic_put(vcpu); kvm_vcpu_pmu_restore_host(vcpu); + if (nested_virt_in_use(vcpu)) + kvm_vcpu_put_hw_mmu(vcpu); + vcpu->cpu = -1; } @@ -1032,8 +1041,13 @@ static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu, vcpu->arch.target = phys_target; + /* Prepare for nested if required */ + ret = kvm_vcpu_init_nested(vcpu); + /* Now we know what it is, we can reset it. */ - ret = kvm_reset_vcpu(vcpu); + if (!ret) + ret = kvm_reset_vcpu(vcpu); + if (ret) { vcpu->arch.target = -1; bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES); diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index c5d1f3c87dbd..5c1a9966ff31 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -151,7 +151,7 @@ static void *kvm_host_va(phys_addr_t phys) * does. */ /** - * unmap_stage2_range -- Clear stage2 page table entries to unmap a range + * kvm_unmap_stage2_range -- Clear stage2 page table entries to unmap a range * @mmu: The KVM stage-2 MMU pointer * @start: The intermediate physical base address of the range to unmap * @size: The size of the area to unmap @@ -174,7 +174,7 @@ static void __unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 may_block)); } -static void unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 size) +void kvm_unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 size) { __unmap_stage2_range(mmu, start, size, true); } @@ -448,7 +448,20 @@ 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; } @@ -474,6 +487,9 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu) mmu->pgt = pgt; mmu->pgd_phys = __pa(pgt->pgd); mmu->vmid.vmid_gen = 0; + + kvm_init_nested_s2_mmu(mmu); + return 0; out_destroy_pgtable: @@ -519,7 +535,7 @@ static void stage2_unmap_memslot(struct kvm *kvm, if (!(vma->vm_flags & VM_PFNMAP)) { gpa_t gpa = addr + (vm_start - memslot->userspace_addr); - unmap_stage2_range(&kvm->arch.mmu, gpa, vm_end - vm_start); + kvm_unmap_stage2_range(&kvm->arch.mmu, gpa, vm_end - vm_start); } hva = vm_end; } while (hva < reg_end); @@ -1415,7 +1431,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, spin_lock(&kvm->mmu_lock); if (ret) - unmap_stage2_range(&kvm->arch.mmu, mem->guest_phys_addr, mem->memory_size); + kvm_unmap_stage2_range(&kvm->arch.mmu, mem->guest_phys_addr, mem->memory_size); else if (!cpus_have_final_cap(ARM64_HAS_STAGE2_FWB)) stage2_flush_memslot(kvm, memslot); spin_unlock(&kvm->mmu_lock); @@ -1432,11 +1448,6 @@ void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen) { } -void kvm_arch_flush_shadow_all(struct kvm *kvm) -{ - kvm_free_stage2_pgd(&kvm->arch.mmu); -} - void kvm_arch_flush_shadow_memslot(struct kvm *kvm, struct kvm_memory_slot *slot) { @@ -1444,7 +1455,7 @@ void kvm_arch_flush_shadow_memslot(struct kvm *kvm, phys_addr_t size = slot->npages << PAGE_SHIFT; spin_lock(&kvm->mmu_lock); - unmap_stage2_range(&kvm->arch.mmu, gpa, size); + kvm_unmap_stage2_range(&kvm->arch.mmu, gpa, size); spin_unlock(&kvm->mmu_lock); } diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index 99e1b97ae3ca..c33cc29756fa 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -19,12 +19,177 @@ #include #include +#include #include +#include #include #include #include "sys_regs.h" +void kvm_init_nested(struct kvm *kvm) +{ + kvm->arch.nested_mmus = NULL; + kvm->arch.nested_mmus_size = 0; +} + +int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu) +{ + struct kvm *kvm = vcpu->kvm; + struct kvm_s2_mmu *tmp; + int num_mmus; + int ret = -ENOMEM; + + if (!test_bit(KVM_ARM_VCPU_HAS_EL2, vcpu->arch.features)) + return 0; + + if (!cpus_have_final_cap(ARM64_HAS_NESTED_VIRT)) + return -EINVAL; + + mutex_lock(&kvm->lock); + + /* + * Let's treat memory allocation failures as benign: If we fail to + * allocate anything, return an error and keep the allocated array + * alive. Userspace may try to recover by intializing the vcpu + * again, and there is no reason to affect the whole VM for this. + */ + num_mmus = atomic_read(&kvm->online_vcpus) * 2; + tmp = krealloc(kvm->arch.nested_mmus, + num_mmus * sizeof(*kvm->arch.nested_mmus), + GFP_KERNEL | __GFP_ZERO); + if (tmp) { + if (kvm_init_stage2_mmu(kvm, &tmp[num_mmus - 1]) || + 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]); + } else { + kvm->arch.nested_mmus_size = num_mmus; + ret = 0; + } + + kvm->arch.nested_mmus = tmp; + } + + mutex_unlock(&kvm->lock); + return ret; +} + +/* Must be called with kvm->lock held */ +struct kvm_s2_mmu *lookup_s2_mmu(struct kvm *kvm, u64 vttbr, u64 hcr) +{ + bool nested_stage2_enabled = hcr & HCR_VM; + int i; + + /* Don't consider the CnP bit for the vttbr match */ + vttbr = vttbr & ~VTTBR_CNP_BIT; + + /* + * Two possibilities when looking up a S2 MMU context: + * + * - either S2 is enabled in the guest, and we need a context that + * is S2-enabled and matches the full VTTBR (VMID+BADDR), which + * makes it safe from a TLB conflict perspective (a broken guest + * won't be able to generate them), + * + * - or S2 is disabled, and we need a context that is S2-disabled + * and matches the VMID only, as all TLBs are tagged by VMID even + * if S2 translation is enabled. + */ + for (i = 0; i < kvm->arch.nested_mmus_size; i++) { + struct kvm_s2_mmu *mmu = &kvm->arch.nested_mmus[i]; + + if (!kvm_s2_mmu_valid(mmu)) + continue; + + if (nested_stage2_enabled && + mmu->nested_stage2_enabled && + vttbr == mmu->vttbr) + return mmu; + + if (!nested_stage2_enabled && + !mmu->nested_stage2_enabled && + get_vmid(vttbr) == get_vmid(mmu->vttbr)) + return mmu; + } + return NULL; +} + +static struct kvm_s2_mmu *get_s2_mmu_nested(struct kvm_vcpu *vcpu) +{ + struct kvm *kvm = vcpu->kvm; + u64 vttbr = vcpu_read_sys_reg(vcpu, VTTBR_EL2); + u64 hcr= vcpu_read_sys_reg(vcpu, HCR_EL2); + struct kvm_s2_mmu *s2_mmu; + int i; + + s2_mmu = lookup_s2_mmu(kvm, vttbr, hcr); + if (s2_mmu) + goto out; + + /* + * Make sure we don't always search from the same point, or we + * will always reuse a potentially active context, leaving + * free contexts unused. + */ + for (i = kvm->arch.nested_mmus_next; + i < (kvm->arch.nested_mmus_size + kvm->arch.nested_mmus_next); + i++) { + s2_mmu = &kvm->arch.nested_mmus[i % kvm->arch.nested_mmus_size]; + + if (atomic_read(&s2_mmu->refcnt) == 0) + break; + } + BUG_ON(atomic_read(&s2_mmu->refcnt)); /* We have struct MMUs to spare */ + + /* Set the scene for the next search */ + kvm->arch.nested_mmus_next = (i + 1) % kvm->arch.nested_mmus_size; + + if (kvm_s2_mmu_valid(s2_mmu)) { + /* Clear the old state */ + kvm_unmap_stage2_range(s2_mmu, 0, kvm_phys_size(kvm)); + if (s2_mmu->vmid.vmid_gen) + kvm_call_hyp(__kvm_tlb_flush_vmid, s2_mmu); + } + + /* + * The virtual VMID (modulo CnP) will be used as a key when matching + * an existing kvm_s2_mmu. + */ + s2_mmu->vttbr = vttbr & ~VTTBR_CNP_BIT; + s2_mmu->nested_stage2_enabled = hcr & HCR_VM; + +out: + atomic_inc(&s2_mmu->refcnt); + return s2_mmu; +} + +void kvm_init_nested_s2_mmu(struct kvm_s2_mmu *mmu) +{ + mmu->vttbr = 1; + mmu->nested_stage2_enabled = false; + atomic_set(&mmu->refcnt, 0); +} + +void kvm_vcpu_load_hw_mmu(struct kvm_vcpu *vcpu) +{ + if (is_hyp_ctxt(vcpu)) { + vcpu->arch.hw_mmu = &vcpu->kvm->arch.mmu; + } else { + spin_lock(&vcpu->kvm->mmu_lock); + vcpu->arch.hw_mmu = get_s2_mmu_nested(vcpu); + spin_unlock(&vcpu->kvm->mmu_lock); + } +} + +void kvm_vcpu_put_hw_mmu(struct kvm_vcpu *vcpu) +{ + if (vcpu->arch.hw_mmu != &vcpu->kvm->arch.mmu) { + atomic_dec(&vcpu->arch.hw_mmu->refcnt); + vcpu->arch.hw_mmu = NULL; + } +} + /* * Inject wfx to the virtual EL2 if this is not from the virtual EL2 and * the virtual HCR_EL2.TWX is set. Otherwise, let the host hypervisor @@ -43,6 +208,24 @@ int handle_wfx_nested(struct kvm_vcpu *vcpu, bool is_wfe) return -EINVAL; } +void kvm_arch_flush_shadow_all(struct kvm *kvm) +{ + int i; + + for (i = 0; i < kvm->arch.nested_mmus_size; i++) { + struct kvm_s2_mmu *mmu = &kvm->arch.nested_mmus[i]; + + WARN_ON(atomic_read(&mmu->refcnt)); + + if (!atomic_read(&mmu->refcnt)) + kvm_free_stage2_pgd(mmu); + } + kfree(kvm->arch.nested_mmus); + kvm->arch.nested_mmus = NULL; + kvm->arch.nested_mmus_size = 0; + kvm_free_stage2_pgd(&kvm->arch.mmu); +} + /* * Our emulated CPU doesn't support all the possible features. For the * sake of simplicity (and probably mental sanity), wipe out a number