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Tue, 17 Nov 2020 10:16:47 -0800 (PST) Date: Tue, 17 Nov 2020 18:15:52 +0000 In-Reply-To: <20201117181607.1761516-1-qperret@google.com> Message-Id: <20201117181607.1761516-13-qperret@google.com> Mime-Version: 1.0 References: <20201117181607.1761516-1-qperret@google.com> X-Mailer: git-send-email 2.29.2.299.gdc1121823c-goog Subject: [RFC PATCH 12/27] KVM: arm64: Introduce a Hyp buddy page allocator From: Quentin Perret To: Catalin Marinas , Will Deacon , Marc Zyngier , James Morse , Julien Thierry , Suzuki K Poulose , Rob Herring , Frank Rowand X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201117_131650_096806_E1C81D11 X-CRM114-Status: GOOD ( 28.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE" , Quentin Perret , android-kvm@google.com, open list , kernel-team@android.com, "open list:KERNEL VIRTUAL MACHINE FOR ARM64 \(KVM/arm64\)" , "moderated list:ARM64 PORT \(AARCH64 ARCHITECTURE\)" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org When memory protection is enabled, the hyp code will require a basic form of memory management in order to allocate and free memory pages at EL2. This is needed for various use-cases, including the creation of hyp mappings or the allocation of stage 2 page tables. To address these use-case, introduce a simple memory allocator in the hyp code. The allocator is designed as a conventional 'buddy allocator', working with a page granularity. It allows to allocate and free physically contiguous pages from memory 'pools', with a guaranteed order alignment in the PA space. Each page in a memory pool is associated with a struct hyp_page which holds the page's metadata, including its refcount, as well as its current order, hence mimicking the kernel's buddy system in the GFP infrastructure. The hyp_page metadata are made accessible through a hyp_vmemmap, following the concept of SPARSE_VMEMMAP in the kernel. Signed-off-by: Quentin Perret --- arch/arm64/kvm/hyp/include/nvhe/gfp.h | 32 ++++ arch/arm64/kvm/hyp/include/nvhe/memory.h | 25 +++ arch/arm64/kvm/hyp/nvhe/Makefile | 2 +- arch/arm64/kvm/hyp/nvhe/page_alloc.c | 185 +++++++++++++++++++++++ 4 files changed, 243 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/kvm/hyp/include/nvhe/gfp.h create mode 100644 arch/arm64/kvm/hyp/nvhe/page_alloc.c diff --git a/arch/arm64/kvm/hyp/include/nvhe/gfp.h b/arch/arm64/kvm/hyp/include/nvhe/gfp.h new file mode 100644 index 000000000000..95587faee171 --- /dev/null +++ b/arch/arm64/kvm/hyp/include/nvhe/gfp.h @@ -0,0 +1,32 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __KVM_HYP_GFP_H +#define __KVM_HYP_GFP_H + +#include + +#include +#include + +#define HYP_MAX_ORDER 11U +#define HYP_NO_ORDER UINT_MAX + +struct hyp_pool { + hyp_spinlock_t lock; + struct list_head free_area[HYP_MAX_ORDER + 1]; + phys_addr_t range_start; + phys_addr_t range_end; +}; + +/* GFP flags */ +#define HYP_GFP_NONE 0 +#define HYP_GFP_ZERO 1 + +/* Allocation */ +void *hyp_alloc_pages(struct hyp_pool *pool, gfp_t mask, unsigned int order); +void hyp_get_page(void *addr); +void hyp_put_page(void *addr); + +/* Used pages cannot be freed */ +int hyp_pool_init(struct hyp_pool *pool, phys_addr_t phys, + unsigned int nr_pages, unsigned int used_pages); +#endif /* __KVM_HYP_GFP_H */ diff --git a/arch/arm64/kvm/hyp/include/nvhe/memory.h b/arch/arm64/kvm/hyp/include/nvhe/memory.h index 64c44c142c95..ed47674bc988 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/memory.h +++ b/arch/arm64/kvm/hyp/include/nvhe/memory.h @@ -6,7 +6,17 @@ #include +struct hyp_pool; +struct hyp_page { + unsigned int refcount; + unsigned int order; + struct hyp_pool *pool; + struct list_head node; +}; + extern s64 hyp_physvirt_offset; +extern u64 __hyp_vmemmap; +#define hyp_vmemmap ((struct hyp_page *)__hyp_vmemmap) #define __hyp_pa(virt) ((phys_addr_t)(virt) + hyp_physvirt_offset) #define __hyp_va(virt) ((void *)((phys_addr_t)(virt) - hyp_physvirt_offset)) @@ -21,4 +31,19 @@ static inline phys_addr_t hyp_virt_to_phys(void *addr) return __hyp_pa(addr); } +#define hyp_phys_to_pfn(phys) ((phys) >> PAGE_SHIFT) +#define hyp_phys_to_page(phys) (&hyp_vmemmap[hyp_phys_to_pfn(phys)]) +#define hyp_virt_to_page(virt) hyp_phys_to_page(__hyp_pa(virt)) + +#define hyp_page_to_phys(page) ((phys_addr_t)((page) - hyp_vmemmap) << PAGE_SHIFT) +#define hyp_page_to_virt(page) __hyp_va(hyp_page_to_phys(page)) +#define hyp_page_to_pool(page) (((struct hyp_page *)page)->pool) + +static inline int hyp_page_count(void *addr) +{ + struct hyp_page *p = hyp_virt_to_page(addr); + + return p->refcount; +} + #endif /* __KVM_HYP_MEMORY_H */ diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile index 33bd381d8f73..9e5eacfec6ec 100644 --- a/arch/arm64/kvm/hyp/nvhe/Makefile +++ b/arch/arm64/kvm/hyp/nvhe/Makefile @@ -10,7 +10,7 @@ lib-objs := clear_page.o copy_page.o memcpy.o memset.o lib-objs := $(addprefix ../../../lib/, $(lib-objs)) obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \ - hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o + hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o page_alloc.o obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \ ../fpsimd.o ../hyp-entry.o ../exception.o obj-y += $(lib-objs) diff --git a/arch/arm64/kvm/hyp/nvhe/page_alloc.c b/arch/arm64/kvm/hyp/nvhe/page_alloc.c new file mode 100644 index 000000000000..6de6515f0432 --- /dev/null +++ b/arch/arm64/kvm/hyp/nvhe/page_alloc.c @@ -0,0 +1,185 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2020 Google LLC + * Author: Quentin Perret + */ + +#include +#include + +u64 __hyp_vmemmap; + +/* + * Example buddy-tree for a 4-pages physically contiguous pool: + * + * o : Page 3 + * / + * o-o : Page 2 + * / + * / o : Page 1 + * / / + * o---o-o : Page 0 + * Order 2 1 0 + * + * Example of requests on this zon: + * __find_buddy(pool, page 0, order 0) => page 1 + * __find_buddy(pool, page 0, order 1) => page 2 + * __find_buddy(pool, page 1, order 0) => page 0 + * __find_buddy(pool, page 2, order 0) => page 3 + */ +static struct hyp_page *__find_buddy(struct hyp_pool *pool, struct hyp_page *p, + unsigned int order) +{ + phys_addr_t addr = hyp_page_to_phys(p); + + addr ^= (PAGE_SIZE << order); + if (addr < pool->range_start || addr >= pool->range_end) + return NULL; + + return hyp_phys_to_page(addr); +} + +static void __hyp_attach_page(struct hyp_pool *pool, + struct hyp_page *p) +{ + unsigned int order = p->order; + struct hyp_page *buddy; + + p->order = HYP_NO_ORDER; + for (; order < HYP_MAX_ORDER; order++) { + /* Nothing to do if the buddy isn't in a free-list */ + buddy = __find_buddy(pool, p, order); + if (!buddy || list_empty(&buddy->node) || buddy->order != order) + break; + + /* Otherwise, coalesce the buddies and go one level up */ + list_del_init(&buddy->node); + buddy->order = HYP_NO_ORDER; + p = (p < buddy) ? p : buddy; + } + + p->order = order; + list_add_tail(&p->node, &pool->free_area[order]); +} + +void hyp_put_page(void *addr) +{ + struct hyp_page *p = hyp_virt_to_page(addr); + struct hyp_pool *pool = hyp_page_to_pool(p); + + hyp_spin_lock(&pool->lock); + if (!p->refcount) + hyp_panic(); + p->refcount--; + if (!p->refcount) + __hyp_attach_page(pool, p); + hyp_spin_unlock(&pool->lock); +} + +void hyp_get_page(void *addr) +{ + struct hyp_page *p = hyp_virt_to_page(addr); + struct hyp_pool *pool = hyp_page_to_pool(p); + + hyp_spin_lock(&pool->lock); + p->refcount++; + hyp_spin_unlock(&pool->lock); +} + +/* Extract a page from the buddy tree, at a specific order */ +static struct hyp_page *__hyp_extract_page(struct hyp_pool *pool, + struct hyp_page *p, + unsigned int order) +{ + struct hyp_page *buddy; + + if (p->order == HYP_NO_ORDER || p->order < order) + return NULL; + + list_del_init(&p->node); + + /* Split the page in two until reaching the requested order */ + while (p->order > order) { + p->order--; + buddy = __find_buddy(pool, p, p->order); + buddy->order = p->order; + list_add_tail(&buddy->node, &pool->free_area[buddy->order]); + } + + p->refcount = 1; + + return p; +} + +static void clear_hyp_page(struct hyp_page *p) +{ + unsigned long i; + + for (i = 0; i < (1 << p->order); i++) + clear_page(hyp_page_to_virt(p) + (i << PAGE_SHIFT)); +} + +static void *__hyp_alloc_pages(struct hyp_pool *pool, gfp_t mask, + unsigned int order) +{ + unsigned int i = order; + struct hyp_page *p; + + /* Look for a high-enough-order page */ + while (i <= HYP_MAX_ORDER && list_empty(&pool->free_area[i])) + i++; + if (i > HYP_MAX_ORDER) + return NULL; + + /* Extract it from the tree at the right order */ + p = list_first_entry(&pool->free_area[i], struct hyp_page, node); + p = __hyp_extract_page(pool, p, order); + + if (mask & HYP_GFP_ZERO) + clear_hyp_page(p); + + return p; +} + +void *hyp_alloc_pages(struct hyp_pool *pool, gfp_t mask, unsigned int order) +{ + struct hyp_page *p; + + hyp_spin_lock(&pool->lock); + p = __hyp_alloc_pages(pool, mask, order); + hyp_spin_unlock(&pool->lock); + + return p ? hyp_page_to_virt(p) : NULL; +} + +/* hyp_vmemmap must be backed beforehand */ +int hyp_pool_init(struct hyp_pool *pool, phys_addr_t phys, + unsigned int nr_pages, unsigned int used_pages) +{ + struct hyp_page *p; + int i; + + if (phys % PAGE_SIZE) + return -EINVAL; + + hyp_spin_lock_init(&pool->lock); + for (i = 0; i <= HYP_MAX_ORDER; i++) + INIT_LIST_HEAD(&pool->free_area[i]); + pool->range_start = phys; + pool->range_end = phys + (nr_pages << PAGE_SHIFT); + + /* Init the vmemmap portion */ + p = hyp_phys_to_page(phys); + memset(p, 0, sizeof(*p) * nr_pages); + for (i = 0; i < nr_pages; i++, p++) { + p->pool = pool; + INIT_LIST_HEAD(&p->node); + } + + /* Attach the unused pages to the buddy tree */ + p = hyp_phys_to_page(phys + (used_pages << PAGE_SHIFT)); + for (i = used_pages; i < nr_pages; i++, p++) + __hyp_attach_page(pool, p); + + return 0; +}