From f41dff4efb918db68923a826e966ca62c7c8e929 Mon Sep 17 00:00:00 2001 From: Quentin Perret Date: Thu, 10 Nov 2022 19:02:53 +0000 Subject: [PATCH] KVM: arm64: Return guest memory from EL2 via dedicated teardown memcache Rather than relying on the host to free the previously-donated pKVM hypervisor VM pages explicitly on teardown, introduce a dedicated teardown memcache which allows the host to reclaim guest memory resources without having to keep track of all of the allocations made by the pKVM hypervisor at EL2. Tested-by: Vincent Donnefort Co-developed-by: Fuad Tabba Signed-off-by: Fuad Tabba Signed-off-by: Quentin Perret Signed-off-by: Will Deacon [maz: dropped __maybe_unused from unmap_donated_memory_noclear()] Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20221110190259.26861-21-will@kernel.org --- arch/arm64/include/asm/kvm_host.h | 7 +----- arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 2 +- arch/arm64/kvm/hyp/nvhe/mem_protect.c | 17 +++++++++------ arch/arm64/kvm/hyp/nvhe/pkvm.c | 27 +++++++++++++++++------ arch/arm64/kvm/pkvm.c | 31 ++++++--------------------- 5 files changed, 40 insertions(+), 44 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 57218f0..63307e7 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -176,12 +176,7 @@ typedef unsigned int pkvm_handle_t; struct kvm_protected_vm { pkvm_handle_t handle; - - struct { - void *pgd; - void *vm; - void *vcpus[KVM_MAX_VCPUS]; - } hyp_donations; + struct kvm_hyp_memcache teardown_mc; }; struct kvm_arch { diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h index 420b87e..b7bdbe6 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h @@ -76,7 +76,7 @@ void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt); int hyp_pin_shared_mem(void *from, void *to); void hyp_unpin_shared_mem(void *from, void *to); -void reclaim_guest_pages(struct pkvm_hyp_vm *vm); +void reclaim_guest_pages(struct pkvm_hyp_vm *vm, struct kvm_hyp_memcache *mc); int refill_memcache(struct kvm_hyp_memcache *mc, unsigned long min_pages, struct kvm_hyp_memcache *host_mc); diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c index 0162afb..94cd48f 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -260,19 +260,24 @@ int kvm_guest_prepare_stage2(struct pkvm_hyp_vm *vm, void *pgd) return 0; } -void reclaim_guest_pages(struct pkvm_hyp_vm *vm) +void reclaim_guest_pages(struct pkvm_hyp_vm *vm, struct kvm_hyp_memcache *mc) { - void *pgd = vm->pgt.pgd; - unsigned long nr_pages; - - nr_pages = kvm_pgtable_stage2_pgd_size(vm->kvm.arch.vtcr) >> PAGE_SHIFT; + void *addr; + /* Dump all pgtable pages in the hyp_pool */ guest_lock_component(vm); kvm_pgtable_stage2_destroy(&vm->pgt); vm->kvm.arch.mmu.pgd_phys = 0ULL; guest_unlock_component(vm); - WARN_ON(__pkvm_hyp_donate_host(hyp_virt_to_pfn(pgd), nr_pages)); + /* Drain the hyp_pool into the memcache */ + addr = hyp_alloc_pages(&vm->pool, 0); + while (addr) { + memset(hyp_virt_to_page(addr), 0, sizeof(struct hyp_page)); + push_hyp_memcache(mc, addr, hyp_virt_to_phys); + WARN_ON(__pkvm_hyp_donate_host(hyp_virt_to_pfn(addr), 1)); + addr = hyp_alloc_pages(&vm->pool, 0); + } } int __pkvm_prot_finalize(void) diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c index 0768307..81835c2 100644 --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c @@ -393,7 +393,7 @@ static void unmap_donated_memory(void *va, size_t size) __unmap_donated_memory(va, size); } -static void __maybe_unused unmap_donated_memory_noclear(void *va, size_t size) +static void unmap_donated_memory_noclear(void *va, size_t size) { if (!va) return; @@ -527,8 +527,21 @@ unlock: return ret; } +static void +teardown_donated_memory(struct kvm_hyp_memcache *mc, void *addr, size_t size) +{ + size = PAGE_ALIGN(size); + memset(addr, 0, size); + + for (void *start = addr; start < addr + size; start += PAGE_SIZE) + push_hyp_memcache(mc, start, hyp_virt_to_phys); + + unmap_donated_memory_noclear(addr, size); +} + int __pkvm_teardown_vm(pkvm_handle_t handle) { + struct kvm_hyp_memcache *mc; struct pkvm_hyp_vm *hyp_vm; struct kvm *host_kvm; unsigned int idx; @@ -547,25 +560,27 @@ int __pkvm_teardown_vm(pkvm_handle_t handle) goto err_unlock; } + host_kvm = hyp_vm->host_kvm; + /* Ensure the VMID is clean before it can be reallocated */ __kvm_tlb_flush_vmid(&hyp_vm->kvm.arch.mmu); remove_vm_table_entry(handle); hyp_spin_unlock(&vm_table_lock); /* Reclaim guest pages (including page-table pages) */ - reclaim_guest_pages(hyp_vm); + mc = &host_kvm->arch.pkvm.teardown_mc; + reclaim_guest_pages(hyp_vm, mc); unpin_host_vcpus(hyp_vm->vcpus, hyp_vm->nr_vcpus); - /* Return the metadata pages to the host */ + /* Push the metadata pages to the teardown memcache */ for (idx = 0; idx < hyp_vm->nr_vcpus; ++idx) { struct pkvm_hyp_vcpu *hyp_vcpu = hyp_vm->vcpus[idx]; - unmap_donated_memory(hyp_vcpu, sizeof(*hyp_vcpu)); + teardown_donated_memory(mc, hyp_vcpu, sizeof(*hyp_vcpu)); } - host_kvm = hyp_vm->host_kvm; vm_size = pkvm_get_hyp_vm_size(hyp_vm->kvm.created_vcpus); - unmap_donated_memory(hyp_vm, vm_size); + teardown_donated_memory(mc, hyp_vm, vm_size); hyp_unpin_shared_mem(host_kvm, host_kvm + 1); return 0; diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c index 8c443b91..cf56958 100644 --- a/arch/arm64/kvm/pkvm.c +++ b/arch/arm64/kvm/pkvm.c @@ -147,8 +147,6 @@ static int __pkvm_create_hyp_vm(struct kvm *host_kvm) handle = ret; host_kvm->arch.pkvm.handle = handle; - host_kvm->arch.pkvm.hyp_donations.pgd = pgd; - host_kvm->arch.pkvm.hyp_donations.vm = hyp_vm; /* Donate memory for the vcpus at hyp and initialize it. */ hyp_vcpu_sz = PAGE_ALIGN(PKVM_HYP_VCPU_SIZE); @@ -167,12 +165,12 @@ static int __pkvm_create_hyp_vm(struct kvm *host_kvm) goto destroy_vm; } - host_kvm->arch.pkvm.hyp_donations.vcpus[idx] = hyp_vcpu; - ret = kvm_call_hyp_nvhe(__pkvm_init_vcpu, handle, host_vcpu, hyp_vcpu); - if (ret) + if (ret) { + free_pages_exact(hyp_vcpu, hyp_vcpu_sz); goto destroy_vm; + } } return 0; @@ -201,30 +199,13 @@ int pkvm_create_hyp_vm(struct kvm *host_kvm) void pkvm_destroy_hyp_vm(struct kvm *host_kvm) { - unsigned long idx, nr_vcpus = host_kvm->created_vcpus; - size_t pgd_sz, hyp_vm_sz; - - if (host_kvm->arch.pkvm.handle) + if (host_kvm->arch.pkvm.handle) { WARN_ON(kvm_call_hyp_nvhe(__pkvm_teardown_vm, host_kvm->arch.pkvm.handle)); - - host_kvm->arch.pkvm.handle = 0; - - for (idx = 0; idx < nr_vcpus; ++idx) { - void *hyp_vcpu = host_kvm->arch.pkvm.hyp_donations.vcpus[idx]; - - if (!hyp_vcpu) - break; - - free_pages_exact(hyp_vcpu, PAGE_ALIGN(PKVM_HYP_VCPU_SIZE)); } - hyp_vm_sz = PAGE_ALIGN(size_add(PKVM_HYP_VM_SIZE, - size_mul(sizeof(void *), nr_vcpus))); - pgd_sz = kvm_pgtable_stage2_pgd_size(host_kvm->arch.vtcr); - - free_pages_exact(host_kvm->arch.pkvm.hyp_donations.vm, hyp_vm_sz); - free_pages_exact(host_kvm->arch.pkvm.hyp_donations.pgd, pgd_sz); + host_kvm->arch.pkvm.handle = 0; + free_hyp_memcache(&host_kvm->arch.pkvm.teardown_mc); } int pkvm_init_host_vm(struct kvm *host_kvm) -- 2.7.4