[RFC PATCH v2 16/26] KVM: arm64: Prepare Hyp memory protection
Will Deacon
will at kernel.org
Wed Feb 3 09:37:10 EST 2021
On Fri, Jan 08, 2021 at 12:15:14PM +0000, Quentin Perret wrote:
> When memory protection is enabled, the Hyp code needs the ability to
> create and manage its own page-table. To do so, introduce a new set of
> hypercalls to initialize Hyp memory protection.
>
> During the init hcall, the hypervisor runs with the host-provided
> page-table and uses the trivial early page allocator to create its own
> set of page-tables, using a memory pool that was donated by the host.
> Specifically, the hypervisor creates its own mappings for __hyp_text,
> the Hyp memory pool, the __hyp_bss, the portion of hyp_vmemmap
> corresponding to the Hyp pool, among other things. It then jumps back in
> the idmap page, switches to use the newly-created pgd (instead of the
> temporary one provided by the host) and then installs the full-fledged
> buddy allocator which will then be the only one in used from then on.
>
> Note that for the sake of symplifying the review, this only introduces
> the code doing this operation, without actually being called by anyhing
> yet. This will be done in a subsequent patch, which will introduce the
> necessary host kernel changes.
>
> Credits to Will for __pkvm_init_switch_pgd.
>
> Co-authored-by: Will Deacon <will at kernel.org>
> Signed-off-by: Will Deacon <will at kernel.org>
> Signed-off-by: Quentin Perret <qperret at google.com>
[...]
> diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
> index c0450828378b..a0e113734b20 100644
> --- a/arch/arm64/include/asm/kvm_hyp.h
> +++ b/arch/arm64/include/asm/kvm_hyp.h
> @@ -100,4 +100,12 @@ void __noreturn hyp_panic(void);
> void __noreturn __hyp_do_panic(bool restore_host, u64 spsr, u64 elr, u64 par);
> #endif
>
> +#ifdef __KVM_NVHE_HYPERVISOR__
> +void __pkvm_init_switch_pgd(phys_addr_t phys, unsigned long size,
> + phys_addr_t pgd, void *sp, void *cont_fn);
> +int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus,
> + unsigned long *per_cpu_base);
> +void __noreturn __host_enter(struct kvm_cpu_context *host_ctxt);
> +#endif
> +
> #endif /* __ARM64_KVM_HYP_H__ */
> diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
> index 43f3a1d6e92d..366d837f0d39 100644
> --- a/arch/arm64/kernel/image-vars.h
> +++ b/arch/arm64/kernel/image-vars.h
> @@ -113,6 +113,25 @@ KVM_NVHE_ALIAS_HYP(__memcpy, __pi_memcpy);
> KVM_NVHE_ALIAS_HYP(__memset, __pi_memset);
> #endif
>
> +/* Hypevisor VA size */
typo: Hypervisor
> +KVM_NVHE_ALIAS(hyp_va_bits);
> +
> +/* Kernel memory sections */
> +KVM_NVHE_ALIAS(__start_rodata);
> +KVM_NVHE_ALIAS(__end_rodata);
> +KVM_NVHE_ALIAS(__bss_start);
> +KVM_NVHE_ALIAS(__bss_stop);
> +
> +/* Hyp memory sections */
> +KVM_NVHE_ALIAS(__hyp_idmap_text_start);
> +KVM_NVHE_ALIAS(__hyp_idmap_text_end);
> +KVM_NVHE_ALIAS(__hyp_text_start);
> +KVM_NVHE_ALIAS(__hyp_text_end);
> +KVM_NVHE_ALIAS(__hyp_data_ro_after_init_start);
> +KVM_NVHE_ALIAS(__hyp_data_ro_after_init_end);
> +KVM_NVHE_ALIAS(__hyp_bss_start);
> +KVM_NVHE_ALIAS(__hyp_bss_end);
> +
> #endif /* CONFIG_KVM */
>
> #endif /* __ARM64_KERNEL_IMAGE_VARS_H */
> diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile
> index 687598e41b21..b726332eec49 100644
> --- a/arch/arm64/kvm/hyp/Makefile
> +++ b/arch/arm64/kvm/hyp/Makefile
> @@ -10,4 +10,4 @@ subdir-ccflags-y := -I$(incdir) \
> -DDISABLE_BRANCH_PROFILING \
> $(DISABLE_STACKLEAK_PLUGIN)
>
> -obj-$(CONFIG_KVM) += vhe/ nvhe/ pgtable.o
> +obj-$(CONFIG_KVM) += vhe/ nvhe/ pgtable.o reserved_mem.o
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/memory.h b/arch/arm64/kvm/hyp/include/nvhe/memory.h
> index ed47674bc988..c8af6fe87bfb 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/memory.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/memory.h
> @@ -6,6 +6,12 @@
>
> #include <linux/types.h>
>
> +#define HYP_MEMBLOCK_REGIONS 128
> +struct hyp_memblock_region {
> + phys_addr_t start;
> + phys_addr_t end;
> +};
> +
> struct hyp_pool;
> struct hyp_page {
> unsigned int refcount;
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/mm.h b/arch/arm64/kvm/hyp/include/nvhe/mm.h
> new file mode 100644
> index 000000000000..f0cc09b127a5
> --- /dev/null
> +++ b/arch/arm64/kvm/hyp/include/nvhe/mm.h
> @@ -0,0 +1,79 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#ifndef __KVM_HYP_MM_H
> +#define __KVM_HYP_MM_H
> +
> +#include <asm/kvm_pgtable.h>
> +#include <asm/spectre.h>
> +#include <linux/types.h>
> +
> +#include <nvhe/memory.h>
> +#include <nvhe/spinlock.h>
> +
> +extern struct hyp_memblock_region kvm_nvhe_sym(hyp_memory)[];
> +extern int kvm_nvhe_sym(hyp_memblock_nr);
> +extern struct kvm_pgtable pkvm_pgtable;
> +extern hyp_spinlock_t pkvm_pgd_lock;
> +extern struct hyp_pool hpool;
> +extern u64 __io_map_base;
> +extern u32 hyp_va_bits;
> +
> +int hyp_create_idmap(void);
> +int hyp_map_vectors(void);
> +int hyp_back_vmemmap(phys_addr_t phys, unsigned long size, phys_addr_t back);
> +int pkvm_cpu_set_vector(enum arm64_hyp_spectre_vector slot);
> +int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot);
> +int __pkvm_create_mappings(unsigned long start, unsigned long size,
> + unsigned long phys, unsigned long prot);
> +unsigned long __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
> + unsigned long prot);
> +
> +static inline void hyp_vmemmap_range(phys_addr_t phys, unsigned long size,
> + unsigned long *start, unsigned long *end)
> +{
> + unsigned long nr_pages = size >> PAGE_SHIFT;
> + struct hyp_page *p = hyp_phys_to_page(phys);
> +
> + *start = (unsigned long)p;
> + *end = *start + nr_pages * sizeof(struct hyp_page);
> + *start = ALIGN_DOWN(*start, PAGE_SIZE);
> + *end = ALIGN(*end, PAGE_SIZE);
> +}
> +
> +static inline unsigned long __hyp_pgtable_max_pages(unsigned long nr_pages)
> +{
> + unsigned long total = 0, i;
> +
> + /* Provision the worst case scenario with 4 levels of page-table */
> + for (i = 0; i < 4; i++) {
Looks like you want KVM_PGTABLE_MAX_LEVELS, so maybe move that into a
header?
> + nr_pages = DIV_ROUND_UP(nr_pages, PTRS_PER_PTE);
> + total += nr_pages;
> + }
... that said, I'm not sure this needs to iterate at all. What exactly are
you trying to compute?
> +
> + return total;
> +}
> +
> +static inline unsigned long hyp_s1_pgtable_size(void)
> +{
> + struct hyp_memblock_region *reg;
> + unsigned long nr_pages, res = 0;
> + int i;
> +
> + if (kvm_nvhe_sym(hyp_memblock_nr) <= 0)
> + return 0;
It's a bit grotty having this be signed. Why do we need to encode the error
case differently from the 0 case?
> +
> + for (i = 0; i < kvm_nvhe_sym(hyp_memblock_nr); i++) {
> + reg = &kvm_nvhe_sym(hyp_memory)[i];
You could declare reg in the loop body.
> + nr_pages = (reg->end - reg->start) >> PAGE_SHIFT;
> + nr_pages = __hyp_pgtable_max_pages(nr_pages);
Maybe it would make more sense for __hyp_pgtable_max_pages to take the
size in bytes rather than pages, since most callers seem to have to do the
conversion?
> + res += nr_pages << PAGE_SHIFT;
> + }
> +
> + /* Allow 1 GiB for private mappings */
> + nr_pages = (1 << 30) >> PAGE_SHIFT;
SZ_1G >> PAGE_SHIFT
> + nr_pages = __hyp_pgtable_max_pages(nr_pages);
> + res += nr_pages << PAGE_SHIFT;
> +
> + return res;
Might make more sense to keep res in pages until here, then just shift when
returning.
> +}
> +
> +#endif /* __KVM_HYP_MM_H */
> diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
> index 72cfe53f106f..d7381a503182 100644
> --- a/arch/arm64/kvm/hyp/nvhe/Makefile
> +++ b/arch/arm64/kvm/hyp/nvhe/Makefile
> @@ -11,9 +11,9 @@ 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 page_alloc.o \
> - cache.o cpufeature.o
> + cache.o cpufeature.o setup.o mm.o
> obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
> - ../fpsimd.o ../hyp-entry.o ../exception.o
> + ../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o
> obj-y += $(lib-objs)
>
> ##
> diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
> index 31b060a44045..ad943966c39f 100644
> --- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
> +++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
> @@ -251,4 +251,35 @@ alternative_else_nop_endif
>
> SYM_CODE_END(__kvm_handle_stub_hvc)
>
> +SYM_FUNC_START(__pkvm_init_switch_pgd)
> + /* Turn the MMU off */
> + pre_disable_mmu_workaround
> + mrs x2, sctlr_el2
> + bic x3, x2, #SCTLR_ELx_M
> + msr sctlr_el2, x3
> + isb
> +
> + tlbi alle2
> +
> + /* Install the new pgtables */
> + ldr x3, [x0, #NVHE_INIT_PGD_PA]
> + phys_to_ttbr x4, x3
> +alternative_if ARM64_HAS_CNP
> + orr x4, x4, #TTBR_CNP_BIT
> +alternative_else_nop_endif
> + msr ttbr0_el2, x4
> +
> + /* Set the new stack pointer */
> + ldr x0, [x0, #NVHE_INIT_STACK_HYP_VA]
> + mov sp, x0
> +
> + /* And turn the MMU back on! */
> + dsb nsh
> + isb
> + msr sctlr_el2, x2
> + ic iallu
> + isb
> + ret x1
> +SYM_FUNC_END(__pkvm_init_switch_pgd)
> +
> .popsection
> diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> index a906f9e2ff34..3075f117651c 100644
> --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> @@ -6,12 +6,14 @@
>
> #include <hyp/switch.h>
>
> +#include <asm/pgtable-types.h>
> #include <asm/kvm_asm.h>
> #include <asm/kvm_emulate.h>
> #include <asm/kvm_host.h>
> #include <asm/kvm_hyp.h>
> #include <asm/kvm_mmu.h>
>
> +#include <nvhe/mm.h>
> #include <nvhe/trap_handler.h>
>
> DEFINE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);
> @@ -106,6 +108,42 @@ static void handle___vgic_v3_restore_aprs(struct kvm_cpu_context *host_ctxt)
> __vgic_v3_restore_aprs(kern_hyp_va(cpu_if));
> }
>
> +static void handle___pkvm_init(struct kvm_cpu_context *host_ctxt)
> +{
> + DECLARE_REG(phys_addr_t, phys, host_ctxt, 1);
> + DECLARE_REG(unsigned long, size, host_ctxt, 2);
> + DECLARE_REG(unsigned long, nr_cpus, host_ctxt, 3);
> + DECLARE_REG(unsigned long *, per_cpu_base, host_ctxt, 4);
> +
> + cpu_reg(host_ctxt, 1) = __pkvm_init(phys, size, nr_cpus, per_cpu_base);
__pkvm_init() doesn't return, so I think this assignment back into host_ctxt
is confusing.
Also, I wonder if these bare numbers would be better hidden behind, e.g.
#define DECLARE_ARG0(...) DECLARE_REG(__VA_ARGS__, 1)
...
#define DECLARE_RET(...) DECLARE_REG(__VA_ARGS__, 1)
but it's cosmetic, so no need to change your patch. Just worried about
off-by-1s causing interesting behaviour!
> +
> +static void handle___pkvm_cpu_set_vector(struct kvm_cpu_context *host_ctxt)
> +{
> + DECLARE_REG(enum arm64_hyp_spectre_vector, slot, host_ctxt, 1);
> +
> + cpu_reg(host_ctxt, 1) = pkvm_cpu_set_vector(slot);
> +}
> +
> +static void handle___pkvm_create_mappings(struct kvm_cpu_context *host_ctxt)
> +{
> + DECLARE_REG(unsigned long, start, host_ctxt, 1);
> + DECLARE_REG(unsigned long, size, host_ctxt, 2);
> + DECLARE_REG(unsigned long, phys, host_ctxt, 3);
> + DECLARE_REG(unsigned long, prot, host_ctxt, 4);
> +
> + cpu_reg(host_ctxt, 1) = __pkvm_create_mappings(start, size, phys, prot);
> +}
> +
> +static void handle___pkvm_create_private_mapping(struct kvm_cpu_context *host_ctxt)
> +{
> + DECLARE_REG(phys_addr_t, phys, host_ctxt, 1);
> + DECLARE_REG(size_t, size, host_ctxt, 2);
Why the size_t vs unsigned long discrepancy with pkvm_create_mappings?
Same with phys_addr_t, although that one probably doesn't matter.
Also, the pgtable API uses an enum type for the prot bits.
> + DECLARE_REG(unsigned long, prot, host_ctxt, 3);
> +
> + cpu_reg(host_ctxt, 1) = __pkvm_create_private_mapping(phys, size, prot);
> +}
> +
> typedef void (*hcall_t)(struct kvm_cpu_context *);
>
> #define HANDLE_FUNC(x) [__KVM_HOST_SMCCC_FUNC_##x] = kimg_fn_ptr(handle_##x)
> @@ -125,6 +163,10 @@ static const hcall_t *host_hcall[] = {
> HANDLE_FUNC(__kvm_get_mdcr_el2),
> HANDLE_FUNC(__vgic_v3_save_aprs),
> HANDLE_FUNC(__vgic_v3_restore_aprs),
> + HANDLE_FUNC(__pkvm_init),
> + HANDLE_FUNC(__pkvm_cpu_set_vector),
> + HANDLE_FUNC(__pkvm_create_mappings),
> + HANDLE_FUNC(__pkvm_create_private_mapping),
> };
>
> static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)
> diff --git a/arch/arm64/kvm/hyp/nvhe/mm.c b/arch/arm64/kvm/hyp/nvhe/mm.c
> new file mode 100644
> index 000000000000..f3481646a94e
> --- /dev/null
> +++ b/arch/arm64/kvm/hyp/nvhe/mm.c
> @@ -0,0 +1,174 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2020 Google LLC
> + * Author: Quentin Perret <qperret at google.com>
> + */
> +
> +#include <linux/kvm_host.h>
> +#include <asm/kvm_hyp.h>
> +#include <asm/kvm_mmu.h>
> +#include <asm/kvm_pgtable.h>
> +#include <asm/spectre.h>
> +
> +#include <nvhe/early_alloc.h>
> +#include <nvhe/gfp.h>
> +#include <nvhe/memory.h>
> +#include <nvhe/mm.h>
> +#include <nvhe/spinlock.h>
> +
> +struct kvm_pgtable pkvm_pgtable;
> +hyp_spinlock_t pkvm_pgd_lock;
> +u64 __io_map_base;
> +
> +struct hyp_memblock_region hyp_memory[HYP_MEMBLOCK_REGIONS];
> +int hyp_memblock_nr;
> +
> +int __pkvm_create_mappings(unsigned long start, unsigned long size,
> + unsigned long phys, unsigned long prot)
> +{
> + int err;
> +
> + hyp_spin_lock(&pkvm_pgd_lock);
> + err = kvm_pgtable_hyp_map(&pkvm_pgtable, start, size, phys, prot);
> + hyp_spin_unlock(&pkvm_pgd_lock);
> +
> + return err;
> +}
> +
> +unsigned long __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
> + unsigned long prot)
> +{
> + unsigned long addr;
> + int ret;
> +
> + hyp_spin_lock(&pkvm_pgd_lock);
> +
> + size = PAGE_ALIGN(size + offset_in_page(phys));
It might just be simpler to require page-aligned size and phys in the
caller. At least, for the vectors that should be straightforward because
I think they're guaranteed not to span a page boundary.
> + addr = __io_map_base;
> + __io_map_base += size;
> +
> + /* Are we overflowing on the vmemmap ? */
> + if (__io_map_base > __hyp_vmemmap) {
> + __io_map_base -= size;
> + addr = 0;
Can we use ERR_PTR(), or does that fail miserably at EL2?
> + goto out;
> + }
> +
> + ret = kvm_pgtable_hyp_map(&pkvm_pgtable, addr, size, phys, prot);
> + if (ret) {
> + addr = 0;
> + goto out;
> + }
> +
> + addr = addr + offset_in_page(phys);
> +out:
> + hyp_spin_unlock(&pkvm_pgd_lock);
> +
> + return addr;
> +}
[...]
> +static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size,
> + unsigned long *per_cpu_base)
> +{
> + void *start, *end, *virt = hyp_phys_to_virt(phys);
> + int ret, i;
> +
> + /* Recreate the hyp page-table using the early page allocator */
> + hyp_early_alloc_init(hyp_pgt_base, hyp_s1_pgtable_size());
> + ret = kvm_pgtable_hyp_init(&pkvm_pgtable, hyp_va_bits,
> + &hyp_early_alloc_mm_ops);
> + if (ret)
> + return ret;
> +
> + ret = hyp_create_idmap();
> + if (ret)
> + return ret;
> +
> + ret = hyp_map_vectors();
> + if (ret)
> + return ret;
> +
> + ret = hyp_back_vmemmap(phys, size, hyp_virt_to_phys(vmemmap_base));
> + if (ret)
> + return ret;
> +
> + ret = pkvm_create_mappings(hyp_symbol_addr(__hyp_text_start),
> + hyp_symbol_addr(__hyp_text_end),
> + PAGE_HYP_EXEC);
> + if (ret)
> + return ret;
> +
> + ret = pkvm_create_mappings(hyp_symbol_addr(__start_rodata),
> + hyp_symbol_addr(__end_rodata), PAGE_HYP_RO);
> + if (ret)
> + return ret;
> +
> + ret = pkvm_create_mappings(hyp_symbol_addr(__hyp_data_ro_after_init_start),
> + hyp_symbol_addr(__hyp_data_ro_after_init_end),
> + PAGE_HYP_RO);
> + if (ret)
> + return ret;
> +
> + ret = pkvm_create_mappings(hyp_symbol_addr(__bss_start),
__hyp_bss_start
> + hyp_symbol_addr(__hyp_bss_end), PAGE_HYP);
> + if (ret)
> + return ret;
> +
> + ret = pkvm_create_mappings(hyp_symbol_addr(__hyp_bss_end),
> + hyp_symbol_addr(__bss_stop), PAGE_HYP_RO);
> + if (ret)
> + return ret;
> +
> + ret = pkvm_create_mappings(virt, virt + size - 1, PAGE_HYP);
Why is the range inclusive here?
> + if (ret)
> + return ret;
> +
> + for (i = 0; i < hyp_nr_cpus; i++) {
> + start = (void *)kern_hyp_va(per_cpu_base[i]);
> + end = start + PAGE_ALIGN(hyp_percpu_size);
> + ret = pkvm_create_mappings(start, end, PAGE_HYP);
> + if (ret)
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static void update_nvhe_init_params(void)
> +{
> + struct kvm_nvhe_init_params *params;
> + unsigned long i, stack;
> +
> + for (i = 0; i < hyp_nr_cpus; i++) {
> + stack = (unsigned long)stacks_base + (i << PAGE_SHIFT);
> + params = per_cpu_ptr(&kvm_init_params, i);
> + params->stack_hyp_va = stack + PAGE_SIZE;
> + params->pgd_pa = __hyp_pa(pkvm_pgtable.pgd);
> + __flush_dcache_area(params, sizeof(*params));
> + }
> +}
> +
> +static void *hyp_zalloc_hyp_page(void *arg)
> +{
> + return hyp_alloc_pages(&hpool, HYP_GFP_ZERO, 0);
> +}
> +
> +void __noreturn __pkvm_init_finalise(void)
> +{
> + struct kvm_host_data *host_data = this_cpu_ptr(&kvm_host_data);
> + struct kvm_cpu_context *host_ctxt = &host_data->host_ctxt;
> + unsigned long nr_pages, used_pages;
> + int ret;
> +
> + /* Now that the vmemmap is backed, install the full-fledged allocator */
> + nr_pages = hyp_s1_pgtable_size() >> PAGE_SHIFT;
> + used_pages = hyp_early_alloc_nr_pages();
> + ret = hyp_pool_init(&hpool, __hyp_pa(hyp_pgt_base), nr_pages, used_pages);
> + if (ret)
> + goto out;
> +
> + pkvm_pgtable_mm_ops.zalloc_page = hyp_zalloc_hyp_page;
> + pkvm_pgtable_mm_ops.phys_to_virt = hyp_phys_to_virt;
> + pkvm_pgtable_mm_ops.virt_to_phys = hyp_virt_to_phys;
> + pkvm_pgtable_mm_ops.get_page = hyp_get_page;
> + pkvm_pgtable_mm_ops.put_page = hyp_put_page;
> + pkvm_pgtable.mm_ops = &pkvm_pgtable_mm_ops;
> +
> +out:
> + host_ctxt->regs.regs[0] = SMCCC_RET_SUCCESS;
> + host_ctxt->regs.regs[1] = ret;
Use the cpu_reg() helper for these?
> +
> + __host_enter(host_ctxt);
> +}
> +
> +int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus,
> + unsigned long *per_cpu_base)
> +{
> + struct kvm_nvhe_init_params *params;
> + void *virt = hyp_phys_to_virt(phys);
> + void (*fn)(phys_addr_t params_pa, void *finalize_fn_va);
> + int ret;
> +
> + if (phys % PAGE_SIZE || size % PAGE_SIZE || (u64)virt % PAGE_SIZE)
> + return -EINVAL;
> +
> + hyp_spin_lock_init(&pkvm_pgd_lock);
> + hyp_nr_cpus = nr_cpus;
> +
> + ret = divide_memory_pool(virt, size);
> + if (ret)
> + return ret;
> +
> + ret = recreate_hyp_mappings(phys, size, per_cpu_base);
> + if (ret)
> + return ret;
> +
> + update_nvhe_init_params();
> +
> + /* Jump in the idmap page to switch to the new page-tables */
> + params = this_cpu_ptr(&kvm_init_params);
> + fn = (typeof(fn))__hyp_pa(hyp_symbol_addr(__pkvm_init_switch_pgd));
> + fn(__hyp_pa(params), hyp_symbol_addr(__pkvm_init_finalise));
> +
> + unreachable();
> +}
> diff --git a/arch/arm64/kvm/hyp/reserved_mem.c b/arch/arm64/kvm/hyp/reserved_mem.c
> new file mode 100644
> index 000000000000..32f648992835
> --- /dev/null
> +++ b/arch/arm64/kvm/hyp/reserved_mem.c
> @@ -0,0 +1,102 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020 - Google LLC
> + * Author: Quentin Perret <qperret at google.com>
> + */
> +
> +#include <linux/kvm_host.h>
> +#include <linux/memblock.h>
> +#include <linux/sort.h>
> +
> +#include <asm/kvm_host.h>
> +
> +#include <nvhe/memory.h>
> +#include <nvhe/mm.h>
> +
> +phys_addr_t hyp_mem_base;
> +phys_addr_t hyp_mem_size;
> +
> +int __init early_init_dt_add_memory_hyp(u64 base, u64 size)
> +{
> + struct hyp_memblock_region *reg;
> +
> + if (kvm_nvhe_sym(hyp_memblock_nr) >= HYP_MEMBLOCK_REGIONS)
> + kvm_nvhe_sym(hyp_memblock_nr) = -1;
> +
> + if (kvm_nvhe_sym(hyp_memblock_nr) < 0)
> + return -ENOMEM;
> +
> + reg = kvm_nvhe_sym(hyp_memory);
> + reg[kvm_nvhe_sym(hyp_memblock_nr)].start = base;
> + reg[kvm_nvhe_sym(hyp_memblock_nr)].end = base + size;
> + kvm_nvhe_sym(hyp_memblock_nr)++;
> +
> + return 0;
> +}
This isn't called by anything in this patch afaict, so it's a bit tricky to
review, especially as I was trying to see how it interacts with
kvm_hyp_reserve(), which reads hyp_memblock_nr.
> +
> +static int cmp_hyp_memblock(const void *p1, const void *p2)
> +{
> + const struct hyp_memblock_region *r1 = p1;
> + const struct hyp_memblock_region *r2 = p2;
> +
> + return r1->start < r2->start ? -1 : (r1->start > r2->start);
> +}
> +
> +static void __init sort_memblock_regions(void)
> +{
> + sort(kvm_nvhe_sym(hyp_memory),
> + kvm_nvhe_sym(hyp_memblock_nr),
> + sizeof(struct hyp_memblock_region),
> + cmp_hyp_memblock,
> + NULL);
> +}
> +
> +void __init kvm_hyp_reserve(void)
> +{
> + u64 nr_pages, prev;
> +
> + if (!is_hyp_mode_available() || is_kernel_in_hyp_mode())
> + return;
> +
> + if (kvm_get_mode() != KVM_MODE_PROTECTED)
> + return;
> +
> + if (kvm_nvhe_sym(hyp_memblock_nr) < 0) {
> + kvm_err("Failed to register hyp memblocks\n");
> + return;
> + }
> +
> + sort_memblock_regions();
> +
> + /*
> + * We don't know the number of possible CPUs yet, so allocate for the
> + * worst case.
> + */
> + hyp_mem_size += NR_CPUS << PAGE_SHIFT;
There was a recent patch bumping NR_CPUs to 512, so this would be 32MB
with 64k pages. Is it possible to return memory to the host later on once
we have a better handle on the number of CPUs in the system?
> + hyp_mem_size += hyp_s1_pgtable_size();
> +
> + /*
> + * The hyp_vmemmap needs to be backed by pages, but these pages
> + * themselves need to be present in the vmemmap, so compute the number
> + * of pages needed by looking for a fixed point.
> + */
> + nr_pages = 0;
> + do {
> + prev = nr_pages;
> + nr_pages = (hyp_mem_size >> PAGE_SHIFT) + prev;
> + nr_pages = DIV_ROUND_UP(nr_pages * sizeof(struct hyp_page), PAGE_SIZE);
> + nr_pages += __hyp_pgtable_max_pages(nr_pages);
> + } while (nr_pages != prev);
> + hyp_mem_size += nr_pages << PAGE_SHIFT;
> +
> + hyp_mem_base = memblock_find_in_range(0, memblock_end_of_DRAM(),
> + hyp_mem_size, SZ_2M);
Why SZ_2M? Guessing you might mean PMD_SIZE, although then we will probably
want to retry with smaller alignment if the allocation fails as this can
again be large with e.g. 64k pages.
> + if (!hyp_mem_base) {
> + kvm_err("Failed to reserve hyp memory\n");
> + return;
> + }
> + memblock_reserve(hyp_mem_base, hyp_mem_size);
> +
> + kvm_info("Reserved %lld MiB at 0x%llx\n", hyp_mem_size >> 20,
> + hyp_mem_base);
> +}
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 278e163beda4..3cf9397dabdb 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1264,10 +1264,10 @@ static struct kvm_pgtable_mm_ops kvm_hyp_mm_ops = {
> .virt_to_phys = kvm_host_pa,
> };
>
> +u32 hyp_va_bits;
Perhaps it would be better to pass this to __pkvm_init() instead of making
it global?
Will
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