Much of the stage-2 manipulation logic relies on being able to destroy block mappings if e.g. installing a smaller mapping in the range. The rationale for this behaviour is that stage-2 mappings can always be re-created lazily. However, this gets more complicated when the stage-2 page-table is used to store metadata about the underlying pages. In such a case, destroying a block mapping may lead to losing part of the state, and confuse the user of those metadata (such as the hypervisor in nVHE protected mode).
To fix this, introduce a callback function in the pgtable struct which is called during all map operations to determine whether the mappings can us blocks, or should be forced to page-granularity level. This is used by the hypervisor when creating the host stage-2 to force page-level mappings when using non-default protection attributes. Signed-off-by: Quentin Perret <[email protected]> --- arch/arm64/include/asm/kvm_pgtable.h | 63 +++++++++++++++++---------- arch/arm64/kvm/hyp/nvhe/mem_protect.c | 16 +++++-- arch/arm64/kvm/hyp/pgtable.c | 20 +++++++-- 3 files changed, 69 insertions(+), 30 deletions(-) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index af62203d2f7a..dd72653314c7 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -75,25 +75,6 @@ enum kvm_pgtable_stage2_flags { KVM_PGTABLE_S2_IDMAP = BIT(1), }; -/** - * struct kvm_pgtable - KVM page-table. - * @ia_bits: Maximum input address size, in bits. - * @start_level: Level at which the page-table walk starts. - * @pgd: Pointer to the first top-level entry of the page-table. - * @mm_ops: Memory management callbacks. - * @mmu: Stage-2 KVM MMU struct. Unused for stage-1 page-tables. - */ -struct kvm_pgtable { - u32 ia_bits; - u32 start_level; - kvm_pte_t *pgd; - struct kvm_pgtable_mm_ops *mm_ops; - - /* Stage-2 only */ - struct kvm_s2_mmu *mmu; - enum kvm_pgtable_stage2_flags flags; -}; - /** * enum kvm_pgtable_prot - Page-table permissions and attributes. * @KVM_PGTABLE_PROT_X: Execute permission. @@ -109,11 +90,41 @@ enum kvm_pgtable_prot { KVM_PGTABLE_PROT_DEVICE = BIT(3), }; -#define PAGE_HYP (KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W) +#define KVM_PGTABLE_PROT_RW (KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W) +#define KVM_PGTABLE_PROT_RWX (KVM_PGTABLE_PROT_RW | KVM_PGTABLE_PROT_X) + +#define PAGE_HYP KVM_PGTABLE_PROT_RW #define PAGE_HYP_EXEC (KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_X) #define PAGE_HYP_RO (KVM_PGTABLE_PROT_R) #define PAGE_HYP_DEVICE (PAGE_HYP | KVM_PGTABLE_PROT_DEVICE) +typedef bool (*kvm_pgtable_want_pte_cb_t)(u64 addr, u64 end, + enum kvm_pgtable_prot prot); + +/** + * struct kvm_pgtable - KVM page-table. + * @ia_bits: Maximum input address size, in bits. + * @start_level: Level at which the page-table walk starts. + * @pgd: Pointer to the first top-level entry of the page-table. + * @mm_ops: Memory management callbacks. + * @mmu: Stage-2 KVM MMU struct. Unused for stage-1 page-tables. + * @flags: Stage-2 page-table flags. + * @want_pte_cb: Callback function used during map operations to decide + * whether block mappings can be used to map the given IPA + * range. + */ +struct kvm_pgtable { + u32 ia_bits; + u32 start_level; + kvm_pte_t *pgd; + struct kvm_pgtable_mm_ops *mm_ops; + + /* Stage-2 only */ + struct kvm_s2_mmu *mmu; + enum kvm_pgtable_stage2_flags flags; + kvm_pgtable_want_pte_cb_t want_pte_cb; +}; + /** * struct kvm_mem_range - Range of Intermediate Physical Addresses * @start: Start of the range. @@ -216,21 +227,25 @@ int kvm_pgtable_hyp_map(struct kvm_pgtable *pgt, u64 addr, u64 size, u64 phys, u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift); /** - * kvm_pgtable_stage2_init_flags() - Initialise a guest stage-2 page-table. + * kvm_pgtable_stage2_init_full() - Initialise a guest stage-2 page-table. * @pgt: Uninitialised page-table structure to initialise. * @arch: Arch-specific KVM structure representing the guest virtual * machine. * @mm_ops: Memory management callbacks. * @flags: Stage-2 configuration flags. + * @want_pte_cb: Callback function used during map operations to decide + * whether block mappings can be used to map the given IPA + * range. * * Return: 0 on success, negative error code on failure. */ -int kvm_pgtable_stage2_init_flags(struct kvm_pgtable *pgt, struct kvm_arch *arch, +int kvm_pgtable_stage2_init_full(struct kvm_pgtable *pgt, struct kvm_arch *arch, struct kvm_pgtable_mm_ops *mm_ops, - enum kvm_pgtable_stage2_flags flags); + enum kvm_pgtable_stage2_flags flags, + kvm_pgtable_want_pte_cb_t want_pte_cb); #define kvm_pgtable_stage2_init(pgt, arch, mm_ops) \ - kvm_pgtable_stage2_init_flags(pgt, arch, mm_ops, 0) + kvm_pgtable_stage2_init_full(pgt, arch, mm_ops, 0, NULL) /** * kvm_pgtable_stage2_destroy() - Destroy an unused guest stage-2 page-table. diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c index 58edc62be6f7..cdace80d3e28 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -89,6 +89,7 @@ static void prepare_host_vtcr(void) id_aa64mmfr1_el1_sys_val, phys_shift); } +static bool host_stage2_want_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot); int kvm_host_prepare_stage2(void *pgt_pool_base) { struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu; @@ -101,8 +102,9 @@ int kvm_host_prepare_stage2(void *pgt_pool_base) if (ret) return ret; - ret = kvm_pgtable_stage2_init_flags(&host_kvm.pgt, &host_kvm.arch, - &host_kvm.mm_ops, KVM_HOST_S2_FLAGS); + ret = kvm_pgtable_stage2_init_full(&host_kvm.pgt, &host_kvm.arch, + &host_kvm.mm_ops, KVM_HOST_S2_FLAGS, + host_stage2_want_pte_cb); if (ret) return ret; @@ -225,9 +227,17 @@ static inline int __host_stage2_idmap(u64 start, u64 end, __ret; \ }) +static bool host_stage2_want_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot) +{ + if (range_is_memory(addr, end)) + return prot != KVM_PGTABLE_PROT_RWX; + else + return prot != KVM_PGTABLE_PROT_RW; +} + static int host_stage2_idmap(u64 addr) { - enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W; + enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_RW; struct kvm_mem_range range; bool is_memory = find_mem_range(addr, &range); int ret; diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index 34cf67997a82..5bdbe7a31551 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -452,6 +452,8 @@ int kvm_pgtable_hyp_init(struct kvm_pgtable *pgt, u32 va_bits, pgt->start_level = KVM_PGTABLE_MAX_LEVELS - levels; pgt->mm_ops = mm_ops; pgt->mmu = NULL; + pgt->want_pte_cb = NULL; + return 0; } @@ -491,6 +493,7 @@ struct stage2_map_data { struct kvm_pgtable_mm_ops *mm_ops; int ret; + bool force_pte; }; u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift) @@ -613,6 +616,9 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level, struct kvm_pgtable *pgt = data->mmu->pgt; struct kvm_pgtable_mm_ops *mm_ops = data->mm_ops; + if (data->force_pte && (level < (KVM_PGTABLE_MAX_LEVELS - 1))) + return -E2BIG; + if (!kvm_block_mapping_supported(addr, end, phys, level)) return -E2BIG; @@ -660,6 +666,9 @@ static int stage2_map_walk_table_pre(u64 addr, u64 end, u32 level, if (data->anchor) return 0; + if (data->force_pte && (level < (KVM_PGTABLE_MAX_LEVELS - 1))) + return 0; + if (!kvm_block_mapping_supported(addr, end, data->phys, level)) return 0; @@ -791,6 +800,7 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size, .memcache = mc, .mm_ops = pgt->mm_ops, .ret = 0, + .force_pte = pgt->want_pte_cb && pgt->want_pte_cb(addr, addr + size, prot), }; struct kvm_pgtable_walker walker = { .cb = stage2_map_walker, @@ -826,6 +836,7 @@ int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size, .mm_ops = pgt->mm_ops, .owner_id = owner_id, .ret = 0, + .force_pte = true, }; struct kvm_pgtable_walker walker = { .cb = stage2_map_walker, @@ -1070,9 +1081,11 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size) return kvm_pgtable_walk(pgt, addr, size, &walker); } -int kvm_pgtable_stage2_init_flags(struct kvm_pgtable *pgt, struct kvm_arch *arch, - struct kvm_pgtable_mm_ops *mm_ops, - enum kvm_pgtable_stage2_flags flags) + +int kvm_pgtable_stage2_init_full(struct kvm_pgtable *pgt, struct kvm_arch *arch, + struct kvm_pgtable_mm_ops *mm_ops, + enum kvm_pgtable_stage2_flags flags, + kvm_pgtable_want_pte_cb_t want_pte_cb) { size_t pgd_sz; u64 vtcr = arch->vtcr; @@ -1090,6 +1103,7 @@ int kvm_pgtable_stage2_init_flags(struct kvm_pgtable *pgt, struct kvm_arch *arch pgt->mm_ops = mm_ops; pgt->mmu = &arch->mmu; pgt->flags = flags; + pgt->want_pte_cb = want_pte_cb; /* Ensure zeroed PGD pages are visible to the hardware walker */ dsb(ishst); -- 2.32.0.402.g57bb445576-goog _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
