diff options
Diffstat (limited to 'kernel/arch/x86/kvm/mmu.h')
| -rw-r--r-- | kernel/arch/x86/kvm/mmu.h | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/kernel/arch/x86/kvm/mmu.h b/kernel/arch/x86/kvm/mmu.h new file mode 100644 index 000000000..0ada65ecd --- /dev/null +++ b/kernel/arch/x86/kvm/mmu.h @@ -0,0 +1,173 @@ +#ifndef __KVM_X86_MMU_H +#define __KVM_X86_MMU_H + +#include <linux/kvm_host.h> +#include "kvm_cache_regs.h" + +#define PT64_PT_BITS 9 +#define PT64_ENT_PER_PAGE (1 << PT64_PT_BITS) +#define PT32_PT_BITS 10 +#define PT32_ENT_PER_PAGE (1 << PT32_PT_BITS) + +#define PT_WRITABLE_SHIFT 1 + +#define PT_PRESENT_MASK (1ULL << 0) +#define PT_WRITABLE_MASK (1ULL << PT_WRITABLE_SHIFT) +#define PT_USER_MASK (1ULL << 2) +#define PT_PWT_MASK (1ULL << 3) +#define PT_PCD_MASK (1ULL << 4) +#define PT_ACCESSED_SHIFT 5 +#define PT_ACCESSED_MASK (1ULL << PT_ACCESSED_SHIFT) +#define PT_DIRTY_SHIFT 6 +#define PT_DIRTY_MASK (1ULL << PT_DIRTY_SHIFT) +#define PT_PAGE_SIZE_SHIFT 7 +#define PT_PAGE_SIZE_MASK (1ULL << PT_PAGE_SIZE_SHIFT) +#define PT_PAT_MASK (1ULL << 7) +#define PT_GLOBAL_MASK (1ULL << 8) +#define PT64_NX_SHIFT 63 +#define PT64_NX_MASK (1ULL << PT64_NX_SHIFT) + +#define PT_PAT_SHIFT 7 +#define PT_DIR_PAT_SHIFT 12 +#define PT_DIR_PAT_MASK (1ULL << PT_DIR_PAT_SHIFT) + +#define PT32_DIR_PSE36_SIZE 4 +#define PT32_DIR_PSE36_SHIFT 13 +#define PT32_DIR_PSE36_MASK \ + (((1ULL << PT32_DIR_PSE36_SIZE) - 1) << PT32_DIR_PSE36_SHIFT) + +#define PT64_ROOT_LEVEL 4 +#define PT32_ROOT_LEVEL 2 +#define PT32E_ROOT_LEVEL 3 + +#define PT_PDPE_LEVEL 3 +#define PT_DIRECTORY_LEVEL 2 +#define PT_PAGE_TABLE_LEVEL 1 + +static inline u64 rsvd_bits(int s, int e) +{ + return ((1ULL << (e - s + 1)) - 1) << s; +} + +int kvm_mmu_get_spte_hierarchy(struct kvm_vcpu *vcpu, u64 addr, u64 sptes[4]); +void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask); + +/* + * Return values of handle_mmio_page_fault_common: + * RET_MMIO_PF_EMULATE: it is a real mmio page fault, emulate the instruction + * directly. + * RET_MMIO_PF_INVALID: invalid spte is detected then let the real page + * fault path update the mmio spte. + * RET_MMIO_PF_RETRY: let CPU fault again on the address. + * RET_MMIO_PF_BUG: bug is detected. + */ +enum { + RET_MMIO_PF_EMULATE = 1, + RET_MMIO_PF_INVALID = 2, + RET_MMIO_PF_RETRY = 0, + RET_MMIO_PF_BUG = -1 +}; + +int handle_mmio_page_fault_common(struct kvm_vcpu *vcpu, u64 addr, bool direct); +void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu); +void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly); + +static inline unsigned int kvm_mmu_available_pages(struct kvm *kvm) +{ + if (kvm->arch.n_max_mmu_pages > kvm->arch.n_used_mmu_pages) + return kvm->arch.n_max_mmu_pages - + kvm->arch.n_used_mmu_pages; + + return 0; +} + +static inline int kvm_mmu_reload(struct kvm_vcpu *vcpu) +{ + if (likely(vcpu->arch.mmu.root_hpa != INVALID_PAGE)) + return 0; + + return kvm_mmu_load(vcpu); +} + +static inline int is_present_gpte(unsigned long pte) +{ + return pte & PT_PRESENT_MASK; +} + +/* + * Currently, we have two sorts of write-protection, a) the first one + * write-protects guest page to sync the guest modification, b) another one is + * used to sync dirty bitmap when we do KVM_GET_DIRTY_LOG. The differences + * between these two sorts are: + * 1) the first case clears SPTE_MMU_WRITEABLE bit. + * 2) the first case requires flushing tlb immediately avoiding corrupting + * shadow page table between all vcpus so it should be in the protection of + * mmu-lock. And the another case does not need to flush tlb until returning + * the dirty bitmap to userspace since it only write-protects the page + * logged in the bitmap, that means the page in the dirty bitmap is not + * missed, so it can flush tlb out of mmu-lock. + * + * So, there is the problem: the first case can meet the corrupted tlb caused + * by another case which write-protects pages but without flush tlb + * immediately. In order to making the first case be aware this problem we let + * it flush tlb if we try to write-protect a spte whose SPTE_MMU_WRITEABLE bit + * is set, it works since another case never touches SPTE_MMU_WRITEABLE bit. + * + * Anyway, whenever a spte is updated (only permission and status bits are + * changed) we need to check whether the spte with SPTE_MMU_WRITEABLE becomes + * readonly, if that happens, we need to flush tlb. Fortunately, + * mmu_spte_update() has already handled it perfectly. + * + * The rules to use SPTE_MMU_WRITEABLE and PT_WRITABLE_MASK: + * - if we want to see if it has writable tlb entry or if the spte can be + * writable on the mmu mapping, check SPTE_MMU_WRITEABLE, this is the most + * case, otherwise + * - if we fix page fault on the spte or do write-protection by dirty logging, + * check PT_WRITABLE_MASK. + * + * TODO: introduce APIs to split these two cases. + */ +static inline int is_writable_pte(unsigned long pte) +{ + return pte & PT_WRITABLE_MASK; +} + +static inline bool is_write_protection(struct kvm_vcpu *vcpu) +{ + return kvm_read_cr0_bits(vcpu, X86_CR0_WP); +} + +/* + * Will a fault with a given page-fault error code (pfec) cause a permission + * fault with the given access (in ACC_* format)? + */ +static inline bool permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, + unsigned pte_access, unsigned pfec) +{ + int cpl = kvm_x86_ops->get_cpl(vcpu); + unsigned long rflags = kvm_x86_ops->get_rflags(vcpu); + + /* + * If CPL < 3, SMAP prevention are disabled if EFLAGS.AC = 1. + * + * If CPL = 3, SMAP applies to all supervisor-mode data accesses + * (these are implicit supervisor accesses) regardless of the value + * of EFLAGS.AC. + * + * This computes (cpl < 3) && (rflags & X86_EFLAGS_AC), leaving + * the result in X86_EFLAGS_AC. We then insert it in place of + * the PFERR_RSVD_MASK bit; this bit will always be zero in pfec, + * but it will be one in index if SMAP checks are being overridden. + * It is important to keep this branchless. + */ + unsigned long smap = (cpl - 3) & (rflags & X86_EFLAGS_AC); + int index = (pfec >> 1) + + (smap >> (X86_EFLAGS_AC_BIT - PFERR_RSVD_BIT + 1)); + + WARN_ON(pfec & PFERR_RSVD_MASK); + + return (mmu->permissions[index] >> pte_access) & 1; +} + +void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm); +#endif |